Exploding wires

This post is prompted in response to the post here
http://www.sciencemadness.org/talk/viewthread.php?tid=11756
much of this is informatively discussed at length in the reference
given by damn2 here _
http://www.sciencemadness.org/talk/viewthread.php?tid=11756&...
Succinctly outlined here _
http://www.teledynerisi.com/0products/8td/page06.html
http://www.teledynerisi.com/0products/8td/index.html
http://www.teledynerisi.com/0products/index.html


It was my understanding the notion of exploding electronic board resistors
was put to rest in this other thread _
http://www.sciencemadness.org/talk/viewthread.php?tid=7266&a...
here we go again _

First some definitions and misconceptions.
There are two applications of electric firing and these are mutually exclusive,
ignition, or alternatively , detonation ( of secondary explosives )

'Xenoid' describes above an elaborate apparatus to ignite rocket motors. I can't help thinking
so much effort for so little gain. I can't think of any reason to do so in quite that way except
that is just how he likes to do it. One can very expediently make a single use improvised
" Hot Bridge Wire " squib ignitor made from a flashlight or torch light bulb. Heating it with a
blowtorch to poke it open with a nail , and fill it with powdered match heads. The flashlight
itself is the only power supply needed and an arbitrary length of hookup wire.
Bulbs are manufactured with small values of resistance, which of course increases many fold
when turned on , limiting the working current. This complicates calculation of adding the
measured ohms of the firing cable. To determine the voltage needed to obtain the working
current its easiest to just test the bulb connected to the firing cable to light it before making
it into an ignitor. Using one more 1.5 volt battery than what is normally required should be
sufficient. Moderately higher voltage drives excessive current through the bulb lessening
it's life in normal use , but as it burns brighter that may be advantageous in this application.
http://www.bulbtown.com/1_0_2_99_Amp_Light_Bulbs_s/665.htm
http://www.bulbtown.com/1_4_9_Volt_Light_Bulbs_s/764.htm

[url][/url]

Primary ( initiating ) explosives ( substituted for match heads ) can be detonated in this same
way. http://en.wikipedia.org/wiki/Blasting_cap
Multiple charges are routinely connected by detonation cord set off from a single blasting cap.
Apart from wearing high impact resistant eyeglasses and face visor , ballistic vest , and tongs
or forceps for handling , thoughtful precaution is necessary when making an electric blasting
cap as the wire leads are effectively a dipole antenna and as such susceptible to radio frequency
broadcast in the vicinity which could resonantly induce current sufficient to heat the bridgewire
( filament in this case ). From the time it is first loaded with explosive and initially been tested
for continuity ( read the following procedure ) to the time when it will be used , the exposed
lead ends must remain twisted together. To ensure there is no hangfire , immediately prior to
use ( by having the cap inside a pit dug into the ground covered with a sand bag ) it is tested
for continuity , a tricky feat that requires a milliampere low voltage source of just under 1 volt.
The cap lead ends are then connected at this time to the cable or wire that will be used for
firing it, which is also first tested for continuity being already shorted and disconnected at the
power end. The final act is to bring the cap from under the sandbag to the main charge of
secondary explosive and inserted into a previously formed opening there , then promptly leaving
the scene to a safe area. The last thing before firing is to un-short the cable end and test again
for continuity before hooking up to power for firing . This is to distinguish an electrical failure
mode from a dud hang fire which may perhaps be still smoldering , ready to explode , in that
case a wait of 15 minutes or more is warranted before approaching the item for inspection.
For a high degree of safety one could instead electrically light a fuse first to then set off the
blasting cap. ( Individuals who snicker and think all this is excessive , are by definition kwels )

[url][/url]

__________________________


The EBW ( exploding bridge wire ) is an altogether different device that initiates detonation of
secondary explosives in direct contact without the use of primary explosives. This is accomplished
by vaporizing a small metal wire by the rapid Joule heating produced by a nearly instantaneous
( very low impedance ) applied electric current. Immediately evident by the very L O U D bang
it makes , note there will be little sound if the wire only melts and drips away much as a fuse.
( See here fusing current ) - http://www.ndrr.com/rmr_faq/Introduction/Fusing-Currents.htm
and also this - http://www.litz-wire.com/New%20PDFs/Fusing_Currents_R2.011609.pdf
* Note that both the above references omit to state that the wire diameter must be C U B E D
. before taking the square root , so , √ ( D X D X D ) , only then multiplied by the coefficient " A "

EBW devices must be within arms reach of the pulsed power source and supplied by a short
low impedance cable typically within 40 - 50 cm. This can be :
Solid copper core RG-8U Coaxial cable ,
[url][/url]

Braided or Rutherford Litzendraht ( Litz ) wire
[url][/url]

http://en.wikipedia.org/wiki/Litz_wire , http://www.litz-wire.com/applications.html ,
http://www.hmwire.com , http://www.hmwire.com/sm.html ,

Goertz flat ribbon cable ,
[url][/url]
similar available plain and much cheaper from _ http://www.alphacoredirect.com/contents/en-us/d53.html

or 2 plys of 12AWG from http://www.decorp.com
[url][/url][url][/url]

http://www.flatwirestore.com/mm5/merchant.mvc?Screen=CTGY&Store...
http://www.tycoelectronics.com/catalog/cinf/en/c/11930/1486
http://www.tycoelectronics.com/catalog/minf/en/152
http://www.ampnetconnect.com/product_groups.asp?grp_id=1660&pat...
http://www.ampnetconnect.com/product_cut_sheet.asp?grp_id=2285&...
even 2 edgewise parallel flat cross section solid grounding strap would do.
http://www.keison.co.uk/furse/conductors_flat_tape.htm
Fralock transformer coil copper tape
http://www.surplussales.com/RF/RFSilv-CoppS.html
_____

Perversely , the uninitiated continue to believe that the bridge wire itself is a resistive element ,
- - W R O N G - -
A bridge wire is just that , an UNINSULATED wire having as low a DC current resistance as
possible. Due to the extremely short time rise of the current , initially conduction occurs only
along the surface , known as " skin effect ", as the wire heats up the resistance increases,
then as the wire melts the resistance drops again and conduction resumes now through the
entire cross section and continues to increase as it becomes vapor. High resistance material
inhibits this progression so that the surface is cooked off forming a vapor boundary layer which
is more conductive , dissipating the discharge as a heat flash , not shock.* Note this is a
principle reason why very fine wire is used in pulses of very short time frames , the current
simply cannot penetrate into the depths of the wire where it needs to be to rapidly heat the wire.

The applicable equation of state is , I = V / R , current I = amps , V = volts , R = ohms
Arithmetically R must be as small as possible to maximize the current. This is why kilovolts
are typically applied , to assure a huge current surge and rise time.

[url][/url]


Another misconception is the available energy provided to the wire.
A capacitor's stored energy according to E = CV^2 /2 , E = Joules , C = farads , V = volts
83 Joules = (.00082 F X 450 X 450 ) / 2
may be adequate to the task were it all to arrive instantaneously - which it cannot , being
a function of time and restrictive circuit characteristics. The determinant will be Power ,
the rate at which the energy can be delivered by the cable to the EBW. Because this is a
rate per second , at initial discharge apparent power seems as if megawatts are on tap.
Read Overview here _http://en.wikipedia.org/wiki/Pulsed_power
Dividing 83 Joules by the discharge time .000160 sec = 0.518 Megawatt average power
discharge time is calculated as follows : see - RC time constant , below

[url][/url]

- RC time constant
Determining the time during which the initial discharge occurs is given by
TC = RC , R = ohms , C = farads ,
TC means Time Constant , a factor which relates the rate at which the capacitor discharges.
Specifically , 63 percent of charged voltage during the first TC leaving 37 percent remaining ,
86 percent of the original after 2 X TC , leaving 13 percent of the total remaining , after the
third TC 95 percent discharge has occurred. Complete discharge is assumed after 5 X TC.
See middle of page here - http://www.kpsec.freeuk.com/capacit.htm
also bottom of this page - http://www.bcae1.com/capacitr.htm
RC TC in depth - http://www.electronics-tutorials.ws/rc/rc_1.html
RC Time Constant Calculator - http://www.cvs1.uklinux.net/cgi-bin/calculators/time_const.cgi

Capacitors exhibit resistance which limits their rate of discharge, known as ESR ( Equivalent
Series Resistance ). Smaller ESR means a shorter RC Time Constant and more power
( energy delivered per unit time ). For the capacitor type and size range applicable typically
around 0.1 ohm or less. Reducing ESR shortens the TC and the current rise time without needing
to have higher voltage to compensate for higher resistance.Very short pulse durations
are only acheived by capacitors having exceptionally low ESR. As these do not have large
capacitance, they must have a very high voltage to store significant energy.
What is a Capacitor ? - http://www.sofia.usra.edu/Edu/materials/activeAstronomy/sec5_capaci...
http://www.bychoice.com/capacitor_DF.pdf
http://www.illinoiscapacitor.com/uploads/papers_application/F8CD49C...
http://www.cartage.org.lb/en/themes/sciences/physics/electromagneti...
http://www.cartage.org.lb/en/themes/sciences/physics/electromagneti...
Equivalent Series Resistance (ESR) of Capacitors - http://www.low-esr.com/QT_LowESR.pdf
Equivalent Series Resistance of Tantulum Capacitors , Both the following PDF's are the same
- http://www.avx.com/docs/techinfo/eqtant.pdf
- http://www.avxtantalum.com/pdf/EQTANT.PDF

- In the opening post of this thread -> http://www.sciencemadness.org/talk/viewthread.php?tid=11756
given 820 uF or .00082 F, assuming a 2 cm 28 AWG EBW
Resistance of EBW = .004 ohm , plus Resistance of cable = .0267 ohm ( sum of core and shields
resistance of 3 meters 10 AWG RG-8U coax , see footnote ## ) , estimated ESR
0.1 ohm ( note that ESR is 3 times greater than the rest of the circuit resistance ) the total
circuit resistance = .131 ohm then TC = RC = (.131 )(.00082 ) =.000107 ~ 107 microseconds

- discharged at 450 volts after one TC the remaining voltage is 167 ( 37 % ) , so by E = CV^2/ 2
( .00082 X 167 X 167 ) / 2 = 11.5 Joules , dividing by the rating of 83 Joules ( 11.5 / 83 ) = 13.8 %
100 % - 13.8 % = 86.2 % of the energy is delivered during the first 107 microseconds. The magic
factor is 1.5 times the TC when the remaining charge is 100 volts ( 22.2 % ) 95 % of the energy
of the capacitor has gone into the line in just 160 millionths of a second. What this means is if
conduction is still occurring only along the surface of the EBW , there will be no loud B A N G !
http://www.probertencyclopaedia.com/cgi-bin/res.pl?keyword=Effectiv...

- Given that frequency is the reciprocal of time , f = 1/ t , then the 160 millionths of a second
translates to a frequency of 6.25 kHz. Well below the 170 kHz where skin effect reduces
cross sectional saturation. Look up 28 AWG , here -> http://www.powerstream.com/Wire_Size.htm
Note that this value would be a mere 2.6 kHz for the 10 AWG coaxial core were it just bare wire
instead of coaxial cable.
_____

Joules needed for vaporization of a 2 cm 28 AWG wire = ( weight of EBW / molar weight Cu ) X
( * *Enthalpy of vaporization of Copper 300 KJ / mol + Heat of fusion 13.1 KJ / mol ) =
( .0145 gm / 63.546 gm/mol ) X ( 313100 J/mol ) = 71.4 Joules
By comparison an equivalent weight of TNT yields 65.5 Joules (.0145 X 4519 Joules/gm )
* * From http://www.webelements.com/copper/thermochemistry.html
weight of bridge wire is easily obtained from this applet here _
http://circuitcalculator.com/wordpress/2007/09/20/wire-parameter-calculator

Resistance of EBW = .004 ohm , Resistance of cable = .0267 ohm ( see footnote ## )
The energy is consumed along the entire circuit's resistance. The portion which will act on
the EBW is: .004 / (.004 +.0267 ) = 0.03 , alternatively a 25 cm length of cable is .0022 ohm
recalculating , .004 / (.004 +.0022 ) = 0.645 , then .645 X 83 Joules = 53.5 Joules
An 83 Joule rated capacitor will not be adequate with inherent circuit losses , and still
be marginal with somewhat thinner wire. A thinner wire has less mass and will require less
energy to vaporize while presenting more resistance and consume a greater portion of the
available energy in the circuit. Worth a try with an aluminum foil ribbon and very short cable
run ~ 25 cm. Remember it must make a very loud bang , if it does not sound like a rifle shot
you have not achieved detonation status.
12AX7 observed in this other post
http://www.sciencemadness.org/talk/viewthread.php?tid=6032&a...
the only energy that matters in a system is that which actually achieves the intent.

_____

Capacitive reactance and Inductive reactance the two components of circuit impedance
behave as an additional form of resistance which interferes with rapid discharge of the
capacitor and transmission of that power as a short pulse. Coaxial power cable limits this
to a maximum of it's characteristic impedance of 50 ohms regardless of length. This value
is only a transmission line design parameter , whereas the actual line impedance of your
particular firing cable depends entirely on the wavelength of the discharge waveform
relative to the cables length , and what is attached on the ends. Given that wavelength
is the speed of light ' c ' divided by the frequency , λ = c / f, or alternatively multiplying
by the time of discharge , wavelength = λ = c X t = ( 300,000,000 X .00016 ) = 48000 meters.
The actual wavelength within the cable is always shorter than this because it slows down
( similar to light when it enters a denser medium ) known as " velocity propagation factor ".
For RG-8U it is 0.84 of light speed. A pulse that is lengthy due to a long discharge time
becomes shorter by the propagation delay inherent to the cable. A cable of just 3 meters
behaves here as a short circuit , exhibiting practically no line impedance to or attenuation
of the discharge pulse. See footnote below - IMPEDANCE EXPLAINED -
Xc = .159 / f C , Xc = capacitive reactance of the capacitor expressed as ohms
f = frequency , C = farads. So , Xc = .159 / ( 6250 X .00082 ) = .031 ohm ( vanishingly small )
* Note the absurdly overpriced Goertz " speaker cable " exhibits a characteristic impedance
of just 2 to 4 ohms by further reducing line induction.
Unrelated to the present topic , a rational perspective on such expensive attributes.
http://www.leedsradio.com/technical/snakeoil-cables.html


Ideally the EBW will have melted by full discharge as the current surge drives through
the lowering resistance and vaporizes the wire. We have observed that the ESR of the
capacitor is the most pronounced inhibitor of circuit performance , throttling the power
available. By the end of the next post it will be evident how the effect of ESR can be
minimized to improve the response and performance by at least two fold.

_____

The power feed cable as selected below must be of large gauge to minimize resistance
( ## 3 meter length of RG-8U coax ) or a braid of Litz cable. Welding cable can
suffice for only very short lengths but the induction becomes significant in the circuits
performance. This is because it acts as a transformer primary , magnetically coupling
with anything electrically conductive even moist ground.

Given everything going for it one can see why this has no application other than for
use in ordnance where the EBW can be snug up against the pulse generator.
A setup for outdoor use will need to have the pulse generator close by which puts it
at hazard if used to detonate explosives. Charging and firing control can be done from
a distance with a 3 wire extension cable. ( See the circuit diagrams - next post - below )

* 28 AWG is a common size used in " wire wrap " electronic board prototyping.
Click thumbnails then click again the pictures here -> http://en.wikipedia.org/wiki/Wire_wrap
My suggestion of 28 AWG is 3 to 4 times thicker than what is usually used for an EBW,
and with much bigger caps. Given that the 1 mil to 3 mil wire otherwise used is AWG 40
and smaller which is much finer than hair one should not stray too far from 28 AWG wire
as selected above. Much smaller wire size as noted requires less effort to explode but
becomes increasingly more difficult to physically work with and prepare. Larger wire
naturally requires greater energy to explode but more importantly the lower frequency
at which skin effect becomes significant will affect cross sectional current saturation.
Fine wire is cheaply obtained from ordinary stranded electric line cord. Count the number
of strands in the wire bundle of a known gauge ( 14 AWG being common ) to derive the
single strand size verified here _ http://www.interstatewire.com/WireTable.htm
http://www.seas.gwu.edu/~ecelabs/appnotes/PDF/techdat/swc.pdf

==> One experimenter's results with videos
http://members.tm.net/lapointe/Wire_Explosions.html
Viewing this setup one immediately can see despite success with fine copper wire that
such a large loop of single conductor must sap considerable energy by inductive losses.
This can't be stressed enough , the faster the current rise time , the greater the need
to minimize induction in the circuit !
Viewing the following videos I ask myself what's wrong with this picture. The widely
separated cables is what , which is in effect a single turn solenoid the induction of
which is responsible for the mediocre results observed.
Capacitor like woelen's - explosion -
http://www.youtube.com/watch?v=CY8bkf7QcVE
same guy with new General Atomics capacitor
http://www.youtube.com/watch?v=QMWRvAI4o2E
Banks of capacitors in parallel have one fatal flaw :
ALL of the energy will discharge into the capacitor that fails destroying it and
perhaps damaging those that are alongside.
[url][/url]
It's essential to design a capacitor bank so that the individual caps can have at
least one terminal disconnected from the common conductor with the other caps
so that it can be individually tested for "leakage current" and signs of impending failure.
http://www.fullnet.com/~tomg/esrscope.htm
Invest in a good RCL bridge meter that can measure this. Better yet get it all in one
package , the most prized of all , Sencore LC 75, 76, 77, 101, 102, 103 ( may be
seen on EBay for ~ 150 to 250 dollars and up ) These can even re-form deteriorated
aluminum electrolytics. The oxide insulating layer will tend to deteriorate in the absence
of a sufficient rejuvenating voltage, and eventually the capacitor will lose its ability to
withstand voltage if voltage is not applied. A capacitor to which this has happened can
often be "reformed" by connecting it to a voltage source through a resistor and allowing
the resulting current to slowly restore the oxide layer.
( See my attachment Equivalent Series Resistance & Maximum Leakage.rtf
next post below in Pulse Power - Firing circuits )
http://bama.edebris.com/download/sencore/lc102/LC102.pdf
Cheaper expedient methods (with oscilloscope ) are available
http://octopus.freeyellow.com/esr.html
http://octopus.freeyellow.com/99.html
All the way at the bottom see ' Scope ESR ' here _
http://www.anatekcorp.com/ttg/tiptrick.htm
_____

- IMPEDANCE EXPLAINED -

http://www.eskimo.com/~ddf/Theory/Char_Z.html
http://www.speedingedge.com/PDF-Files/BTS002_Characteristic_Impedan...
The activity in a 3 meter cable at the discharge frequency of 6.25 kHz being very much
less than a quarter wavelength is seen at the extreme right side of this diagram here_
http://www.tpub.com/content/neets/14182/css/14182_150.htm
http://www.allaboutcircuits.com/vol_2/chpt_14/5.html
http://www.epanorama.net/documents/wiring/cable_impedance.html , See the following
- Cables characteristics at high frequencies
- Why attenuation figures tend to increase with increasing frequency ?
Impedance calculations ( scroll down )
http://ocarc.ca/coax.htm
http://www.mantaro.com/resources/impedance_calculator.htm
http://hamradio.arc.nasa.gov/coaxcableloss.html
http://74.125.93.104/search?q=cache:xfy31beGKowJ:hamradio.arc.nasa.gov/coaxcableloss.html+%22Belden+9913%22&cd=58&hl=en&ct=c lnk&gl=us

FOOTNOTE

## 3 meter length of Belden 9913 10 AWG solid copper core RG-8U coax , .0089 ohms / meter
( sum of both core and shield resistance )
RF9913 - $ 0.76 cents ft ( recommended vendor )
- http://www.radiobooks.com/products/rf910.htm
- http://www.radiobooks.com/rwcoax.htm
25 ft cable + UHF connectors, or custom size ready made - $39.95
- http://www.radiobooks.com/products/ca9913.htm

An RG-213 stranded conductor 7 X 21 AWG + UHF connectors, ready made cable
may be suitable to sustain a multi kilojoule pulse for modest power throughput
( rated for 5 kilowatt ( 250 V X 20 amp ) due to the effective cross section being
half that of solid core RG-8U, is cheaply available here _
http://www.buckscom.com/catalog/index.php?main_page=popup_image&...
http://www.buckscom.com/catalog/index.php?main_page=product_info&am...
This one is preferable for applications at kilovolts having a very short time pulse.


Belden 9913 - 0.79 cents/foot ( alternative more expensive vendors )
http://www.theantennafarm.com/catalog/index.php?main_page=product_i...
http://www.signalpros.com/index_files/Page3071.htm
http://www.progressive-concepts.com/info/item.html?id=68
RG-8U Cable specifications and data -
http://www.contactcables.com/products/Belden/Belden9913datasheet.pd...
http://www.alliedelec.com/Images/Products/Datasheets/BM/BELDEN_WIRE...
http://sigma.octopart.com/30985/datasheet/Belden-9913-010500.pdf
http://www.belden.com/pdfs/03Belden_Master_Catalog/06Coaxial_Cables...
( page 6.70 )


Fusing current
http://www.ndrr.com/rmr_faq/Introduction/Fusing-Currents.htm
http://www.litz-wire.com/New%20PDFs/Fusing_Currents_R2.011609.pdf
http://www-d0.fnal.gov/hardware/cal/lvps_info/engineering/wirefusin...
http://www.interfacebus.com/Reference_Cable_AWG_Sizes.html
http://www.interfacebus.com/Aluminum_Wire_AWG_Size.html

Wire chart
Solid conductor
http://amasci.com/tesla/wire1.html
http://www.powerstream.com/Wire_Size.htm

Stranded conductor
http://www.interstatewire.com/WireTable.htm
http://www.seas.gwu.edu/~ecelabs/appnotes/PDF/techdat/swc.pdf

Wire calculator
http://circuitcalculator.com/wordpress/2007/09/20/wire-parameter-calculator

Unit conversion
http://www.allconversions.com


__________________________________________

Pulse Power - Firing circuits

All the previous analysis presupposes the capacitor is a stand alone power source connected in a
closed loop with the EBW. Energy storage capacitors as these below, while suitable for exploding
wires , are large and unwieldy. A high voltage power supply is also needed to charge them.

240 uF 5000 Volts - 3000 Joules
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=350128516137

[url][/url]

http://www.gaep.com/capacitors.html


To provide a large power pulse , a current surge generator is a better arrangement.
By intentionally causing the a.c. power line to short circuit through the EBW , this enables
a very large power pulse to be directly applied with minimal , relatively inexpensive hardware.
In this scheme the capacitor voltage discharges through a spark gap to complete a circuit
with the a.c. power line , resulting in conduction of a huge current surge ( termed " in rush
current ") through the firing cable. This is known as '" Power OR " mode of operation , a
" shunt " diode channels this " follow current " from the a.c. line conducted by the arc.
See F O O T N O T E S bottom of the next post following
Also read here beginning the 3rd paragraph at left _
http://img11.imagevenue.com/img.php?loc=loc284&image=05761_Magnetizing_.jpg
A current surge of hundreds of amps during one half cycle of the a.c. power line
frequency can be tolerated only as a self terminated transient event to prevent damage
to the firing circuit and in particular the a.c. power line. The EBW additionally serves as
the circuit protection fuse , taking only just the power used to explode.
A 300 amp surge through a 2 cm 28 AWG wire by P = R I^2 = .004 ( 300 X 300 ) = 360 watts ,
more than 5 times what was determined necessary to be vaporized. Note that much more
power is consumed by the rest of the power line circuit which heats up considerably though
manageably in a single shot event. Line transients as these are commonly handled by
commercial surge suppressors discussed here - http://www.zerosurge.com/PDF/PQ94.pdf

_____

Drawing ' A ' ( attachment ) restricts the capacitor current to only the firing circuit by having
the capacitor ' C ' parallel with the a.c. line. Synchronizing a.c. line commutation to occur
in phase with the capacitive discharge is facilitated by a triggered spark gap or gas tube ' gg '
as part of the capacitor EBW circuit - Drawing ' B '
See footnote - Triggered Switches , in the post following this one and
- http://www.angelfire.com/80s/sixmhz/trigatron.html
This allows the peak voltage of the a.c. line to trigger the gas gap into conduction.
A diode ' d ', restricts triggering to the phase when the a.c. line voltage has
the same polarity as the caps. This arrangement does not receive the power boost
provided by having the capacitors in series with the a.c. line and will not be considered further.
3 terminal gas tube - 2 to be used in parallel & need to have leads thickened - $ 3.02 each
- http://www.mouser.com/Search/Refine.aspx?Keyword=871-B88069X8440B20...
- http://www.epcos.com/inf/100/ds/t81a90xx8440b202.pdf

Drawing ' C ' shows the capacitor ' C ' in series with the EBW and the a.c. power line. The
problem of a.c. commutation synchronization is solved by a spark gap ' G ' which conducts
in phase at peak a.c. power line voltage. Having the a.c. power line in series with the
capacitor has an additional benefit that the a.c. line voltage and capacitor voltage add
together increasing the voltage to the EBW , improving the current rise time. A large
diode ' D ' provides a path for the resulting current surge generated in the firing circuit.

_____

* * * Note that all the following circuits are divided into a charging and switching part shown
on the left side of each drawing , and the power storage part shown on the right side of the
same drawing. The entire circuit is interconnected across some distance with a 3 conductor
cable serving as an extension cord. Each conductor is labeled
' Top ' , ' Mid ' , ' Bot ' ( Top , Middle , Bottom )
This arrangement also charges the extension cable to the same static voltage as the capacitors.
which adds the cable's capacitance to the firing circuit , reducing the damping at discharge.
' Top ' and ' Mid ' conductors flow electron current to the left.
' Bot ' conductor flows current to the right.
( This is true for all these circuits , although charging phases may have different current paths. )

Suitable cable is of the type used for connecting RV ( Recreational Vehicles )
and trailers to the electric utility main grid , RV 30 Amp Generator Cord , 10/3
( The leading number is the gauge AWG followed by the number of conductors )
Characteristic impedance for twisted pair of this type would be somewhere 100 to 200 ohms
See http://www.mantaro.com/resources/impedance_calculator.htm
Conductor inductance calculations ( nice to know not really all that useful here )
http://www.kolb-net.de/pulsedpower.html - - scroll down
A very good price is less than a dollar a foot. 500 foot loop circuit resistance = .509 ohm
http://wesbellwireandcable.com/PortableCord.html
http://wesbellwireandcable.com/SOOW/SOOW10-3.html - 250 ft - $ 247.50
http://www.americord.com/bulk-cable/prod_537.html - 250 ft - $ 217.50
Cord Nomenclature
http://www.americord.com/glossary
http://www.cables.com.tw/yuefeng/glossary.htm

Crimped and soldered terminal lugs with screws are to be used to hook up the
3 conductor connecting cable.

Plugs and receptacles to connect the charging and switching circuit to the a.c line.
http://en.wikipedia.org/wiki/IEC_connector , IEC 320 C19 / C20 , cords are not available
ready made in 30 amp rating, but can certainly be wired with 10 AWG wire and provide a
secure connection , the pins are robust enough and provide better moisture seal.
[url][url]
The following rewireable plug must have the 2 piece mating seam sealed with epoxy
http://www.mouser.com/Search/Refine.aspx?Keyword=4789.1200
http://www.schurterinc.com/pdf/english/typ_4789.pdf
http://www.mouser.com/Search/Refine.aspx?Keyword=4797.0015
http://www.schurterinc.com/pdf/english/typ_4797.pdf
http://www.apcmedia.com/salestools/SADE-5TNRML_R0_EN.pdf
http://www.feller-at.com/English/Feller-GP-E.htm
NEMA Standard connectors ( If you must , use these , but are comparatively very large )
http://www.hubbellcatalog.com/wiring/catalogpages/section-b.pdf
see B-17 to B-19

_____

Drawing ' D ' shows a practical circuit having the minimum components.
Single Pole Single Throw / NO ( normally open ) switch ' S ' connects power to charge
the capacitor(s) ' C '. Electron current flows through resistance ' R ', and parallel
resistor ' r ' with series ' LED ' light emitting diode , through diode ' dx ' and
' Mid ' conductor , collecting in the negative ( - ) terminal of the the capacitor(s) ' C ',
displacing current out of the positive ( + ) terminal flowing back through ' Top ' conductor
and shunt diode ' D ' to the a.c. source. As it is charged , light emitting diode ' LED '
momentarily flickers on then darkens indicating that charging has occurred. Resistance ' R '
is to protect the small diode ' dx ' from excessive current when charging starts ).


* * * For added safety a 10 amp fast acting circuit breaker ' X ' provides redundant
protection for domestic wiring , serving also as a switch it now does the actual firing
when turned on. The charging circuit is F I R S T switched off by normally open switch ' S '
before the charged circuit can be fired.
Circuit breaker ' X ' fires the circuit by applying the a.c. line voltage in series with the cap(s) ,
effectively doubling the circuit voltage which arcs into conduction the Gas Gap arrestor ' gg '
near the peak of the a.c. sine wave. ' Top ' conductor channels the resulting current surge
left and down shunt diode ' D ' to the a.c. source.
In practice the 325 volt peak is minimal and very marginal to produce an arc across a spark gap ,
better is a " Gas Gap Arrestor " ( use 2 or even 3 in parallel and solder thicker leads on each )
' gg ' - Gas Gap Arrestor - 444-GT-230L - $ 3.09
http://www.mouser.com/Search/Refine.aspx?Keyword=444-GT-230L
http://www.mouser.com/catalog/specsheets/XC-600002.pdf
' gg ' - Gas Gap Arrestor - (RMO) CG2-230L , middle of this page - $ 2.75
http://www.surplussales.com/Semiconductors/SemiCTransSup.html
[url][/url]
http://sigma.octopart.com/510848/datasheet/Littelfuse-CG2230L.pdf
http://octopart.com/search?q=CG2-230L , cheapest at Mouser
http://www.mouser.com/Search/Refine.aspx?N=254139&Keyword=CG2-2... - $ 1.89
' X ' - Single Pole circuit breaker - $ 10.99
http://www.mouser.com/Search/Refine.aspx?Keyword=845-1BU10R
http://www.altechcorp.com/PDFS/R-Series.pdf
http://www.mouser.com/catalog/637/1795.pdf
- @ $2 each set of 3 breakers held by pins this has two 15 amp breakers which can work
and is cheap enough to try out but needs to be dismantled
http://www.sciplus.com/singleItem.cfm/terms/348
[url][/url]
' S ' - Switch SPST / no - (SWP) 1175 , lower third this page - $ 3.75
http://www.surplussales.com/Switches/SWPushB-1.html
[url][/url][url][/url]
' R ' - 30 ohm 5% 15W Power Resistors - $ 0.63 cents X 8 resistors
( 2 sets of 4 are to be wired in series for a total equivalent resistance of 15 ohms )
http://www.mouser.com/Search/Refine.aspx?Keyword=280-CR15-30-RC
http://www.mouser.com/catalog/specsheets/XC-600041.pdf
' r ' - 8.2 kohm 5% 1/4W - $ 0.22 cents
http://www.mouser.com/Search/Refine.aspx?Keyword=30BJ250-8.2K
' LED ' - Green LED - $ 0.26 cents
http://www.mouser.com/Search/Refine.aspx?Keyword=351-5502-RC
' LED ' - Green LED - (SDI) LTL-4233 - $ 0.15 cents
http://www.surplussales.com/Bulbs-Incan-Panel/LEDDisplay.html
_____

Available capacitors that have a higher working voltage than the ~ 162 Volt peak
that comes from the wall socket , require this voltage to be stepped up.

Drawing ' E ' has the capacitor charged to a higher voltage with a transformer included in the circuit.
Switch ' S ' flows electron current through diode ' dy ' into primary coil ' p ' of transformer ' T ' and
' Bot ' conductor back to the a.c. source , inducing a current in secondary coil ' s ' of transformer ' T '.
Current flows through diode ' dx ' into ,' Mid ' conductor collecting in the negative ( - ) terminal of
capacitors(s) ' C ' charging the elevated voltage , displacing current out of the positive ( + ) terminal
flowing back through ' Top ' conductor down resistor ' R ', and parallel resistor' r ' with series light
emitting diode ' LED ', into 'secondary coil ' s ' of transformer ' T '.
( * * where the wire crosses ' Mid ' conductor there is N O connection )
Light emitting diode ' LED ' momentarily flickers on then darkens indicating that charging has occurred.
Firing as already explained is done by circuit breaker ' X ' with the charging circuit F I R S T
switched off by normally open switch ' S ' before the charged circuit can be fired..

_____

Alternatively as explained in Drawing ' F ' using another capacitor as a half wave
voltage doubler , ramps up the charging voltage to 2 times the a.c. line voltage.
In phase - 1 - the capacitor is charged , then in phase - 2 - the reverse voltage
of the a.c.line and the just charged capacitor add together in series aiding effectively doubling.
Illustrated here _
http://www.gallawa.com/microtech/doubler.html

Motor ' start ' capacitors are bipolar electrolytics , also called Non-Polarised or NP capacitors
and are the most suitable for use in voltage doubling as they are designed for a.c. operation ,
but only if run briefly. Those with a Voltage rating higher than the ~ 125 VAC minimally necessary
can be run for just a little longer before overheating ( over 85º C , impairment will occur )
(Cy) ' 270-324 uF, 250 VAC ( the range specifies plus or minus 10% variance from 300 uF )
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200326166634
http://www.amazon.com/dp/B000LERFO4 , ( the point here is shop around )
These here are perfectly adequate _
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=230281260691 - $ 4 each
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370198861276
Motor ' run ' caps can operate continuously but have much less capacitance, or are
much more expensive for equivalent capacitance, and larger.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=310028799378 - $ 12 each
Capacitor testing - http://toad.net/~jsmeenen/capacitor.html


U.S. a.c. power lines typically achieve a peak of ~ 162 volts which provides
the equivalent of 115 volts direct current, called R.M.S. ( root mean square ).
You may wonder why a.c. capacitors have the seemingly odd rating of 125 volts.
60 cycle a.c. is 120 half cycles of alternating polarity, voltage rises from zero
to peak voltage after 1/240 of a second (.004167) ( yellow portion shown below )
and over the next 1/240 of a second drops back to zero again ( green portion )
repeating this rise and fall but in reverse polarity for the following half cycle.
( orange and lime )
[url][/url]

This sets the time available for the percentage of the supplied line voltage a
capacitor will charge up to during the rise of one half cycle. It is not instantaneous.
Re-arranging the folrmula : Xc = .159 / f C , C = farads
f = frequency , Xc = capacitive reactance of the capacitor expressed as ohms ,
thus : XcC = .159 / f , = .159 / 60 , = .00265 , which is effectively the minimum
RC time constant ( TC ) for any capacitor at this frequency ( without considering
additionally the ESR which will make the time constant longer ) It does not matter
what size capacitor or what voltage is applied to it, this value is set in stone, it
is characteristic of 60 cycle a.c. and cannot be changed. Dividing the rise time
.004167 by .00265 , = 1.57 TC ( Time constants ) works out to 79 percent of
peak a.c. line voltage , or 128 volts. This in practice will never be seen due
to the resistance present in the capacitor, this despite that the capacitor will
still be charging slightly even as the a.c. line voltage is dropping , until both are
equal. As the applied a.c. voltage decreases the capacitor will discharge through
the a.c. source. The capacitor will not be completely discharged when the a.c.
line voltage reverses polarity, but as the polarity is now the same as the capacitor
polarity, the voltages aid, quickly discharging the capacitor the rest of the way.
When the applied a.c voltage reverses direction, the capacitor is charged again,
and the entire process is repeated with the next half cycle of the a.c. waveform.
The waveform of an applied sinusoidal a.c.voltage will remain unchanged and only
its amplitude ( peak value ) will be affected. Hence when measuring the voltage
pole to pole on a capacitor in series with an a.c. line you detect a voltage drop,
just as though it were a resistor, this is the capacitive reactance.
http://www.electronics-tutorials.ws/capacitor/cap_8.html

In a half wave voltage doubler , diodes are used to block one phase of the
a.c. waveform so that the capacitor remains charged when the polarity is
reversed. When the polarity again changes , charging continues where it left
off incrementally raising the voltage charged in the capacitor ever closer to
the a.c. supply voltage.

_____

Drawing ' G ' shows this scheme.
- In the first a.c. phase
current flows up from ' Bot ' conductor through resistor ' R ', and parallel resistor ' r '
with series ' LED ' light emitting diode , to motor start capacitor ' Cy ' , diode ' dy ', and
switch ' S ' back to the a.c. source. ( Resistance ' R ' is necessary to protect the
small diodes ' dx , dy , dz ' from excessive current when charging starts ).
- In the next a.c. phase
switch ' S ' flows current through diode ' dx ' , into ' Mid ' conductor,
collecting in the negative ( - ) terminal of capacitor(s) ' C ', displacing current out of
the positive ( + ) terminal flowing through ' Top ' conductor , and down diode ' dz '
( * * NOTE where the wire crosses ' Mid ' conductor there is N O connection )
into motor start capacitor ' Cy ' where the a.c. line voltage acts in series aiding , to
raise the charging voltage on capacitor(s) ' C ' to double a.c. line voltage. As it is
charged , light emitting diode ' LED ' momentarily flickers on then darkens indicating
that charging has occurred. Firing is as before done by circuit breaker ' X ' and switch ' S '
turned off F I R S T before the charged circuit can be fired.

When fired , the a.c. line voltage applied in series aiding effectively raises the circuit
voltage to 3 times the a.c. line voltage , enough for spark gap ' G ' to arc into
conduction , current surges into the positive ( + ) terminals of cap(s) ' C ' displacing
current from the negative ( - ) terminals of capacitor(s) ' C ' left through
' Mid ' conductor and circuit breaker ' X '. ' Top ' conductor channels the
current surge left and down shunt diode ' D ' to the a.c. source.

' dx , dy , dz ' - Small ~ 6 amp diodes - (SDI) MR756 - $ 0.30 cents
( 2 of these are to be wired in parallel for each of ' dx , dy , dz ' a total of 6 diodes )
found down a bit from the top , use the " find on this page " function of your browser
http://www.surplussales.com/Semiconductors/Diodes-Rectifiers-5.html
' G ' - Air Gap - 350 to 600 volts - (RMO) WP438 - near the bottom of this page - $ 3
http://www.surplussales.com/Semiconductors/SemiCTransSup.html
[url][/url]
Using Rectifiers In Voltage Multiplier Circuits
http://www.eettaiwan.com/ARTICLES/2001JUN/2001JUN14_AMD_AN2009.PDF

_____

Drawing ' H ' Omitted for clarity but an essential part of any
such devices is a means for safely discharging the stored energy of a bank of capacitors.
This must be attached and operable before the capacitors are ever charged . Under no
circumstances E V E R handle any part of these devices when charged except to fire !
Until after you have completed the ritual described in the next 2 paragraphs the circuit must
be considered to be charged even if it has been fired - there may still be residual charge.

Attached to ' Top ' conductor parallel with the shunt diode ' D ' is a 2 meter length of wire
with it's other end soldered to a strip of metal on one edge of a small wood block ' B '.
On the opposite edge of wood block ' B ' is another strip of metal soldered with a wire that's
hooked to one terminal of an otherwise unconnected a.c. plug ' E ' ( kept safely inside of
a glass jar ) this will be inserted instead of the power cord into the surge generator.
Wood block ' B ' is to be weighed and submerged in a small bucket of water acidified with
a supermarket bought pint bottle of lime juice ( citric acid ). This water " resistor " will harmlessly
dissipate the charge.

To discharge by using this circuit instead , the entire device must F I R S T be powered off
by disconnecting from the a.c. line altogether and instead connected to plug ' E '
Switch On circuit breaker ' X ' to conduct the charge through the corresponding
terminal of the a.c. plug into the receptacle wired to the water bucket.

This above is simply a very cheaply implemented expedient contrivance to obviate
more elaborate alternative permanent wiring to the circuit which will be outlined
in the closing post. A circuit can include instead a compact drain resistor network.
Wire wound power resistors can withstand Intermittent loading 10 times their rated
power for short pulse durations provided duty cycle limitations are observed. The
best compact size and price per watt is for wire wound cement types in 15 or 25
watt rating.
Remember that 95 % of the energy will dump during the first 1.5 RC time constant.
The reciprocal of capacitance 1/C is the resistance value for an RC time constant
of one second. This means that 95 % discharge of energy will occur in 1.5 seconds.
To provide an equivalent resistance that gives a discharge time long enough to stay
within the power handling capabilities of the resistor network first calculate capacitor
bank energy. An example using 6000 uF charged at 450 volts , E = CV^2/ 2 = 607 Joules
= ( .006 X 450 X 450 ) / 2 . Divide 607 Joules by the maximum excess loading factor
10 , to obtain the combined watt rating of the resistors to be used. 60.7 is most
closely 4 X 15 watt resistors. Now divide " 10 " by the capacitance thus 10/.006 ,
to give a value of 1667 ohms ( 1600 nearest manufactured value ).
Alternatively , r.m.s. discharge voltage (.707 X 450 ) is 318. Using P = V^2/ R
re-arranging to R = V^2/ P , ( 318 X 318 )/60.7 = 1666 ohm , same thing
* Dividing V^2 by full value , 607 Joules , resistance is 167 ohm same as with 1/C .
1600 ohms will discharge 95 % in 15 seconds , total discharge after 50 seconds,
why it is advisable to overload the resistors and use much less ressitance value,
by choosing instead to divide 1.5 or 2 by the capacitance .
A series of 4 groups , each with 4 resistors in parallel , 16 total ,
costing from $ 9.12 to $ 15.84 - See Mouser catalog link below _
can be secured on both sides of a thin aluminum plate ( If all resistors are the
same value then that value will be the equivalent combined resistance ) and
will give adequate heat sinking 10 times the actual 240 or 400 watt rating.
Using P = V^2/ R ( 318 X 318 )/62 = 1631 watts , what a hair blower/dryer
consumes per second. Choosing a 62 Ohm resistor , one group of 4 in parallel can
serve double purpose as the current limiting resistance for the charging circuit.
http://www.mouser.com/Search/Refine.aspx?N=4141191+4294966099+42945...
http://www.mouser.com/Search/Refine.aspx?N=4141191+4294966099+42945...
http://www.mouser.com/catalog/specsheets/XC-600041.pdf

_____

Aluminum electrolytic capacitors provide the highest energy pulse for their size.
Capacitance and voltage vary inversely , you will find those sizes having optimal
energy storage occurs at a few thousand uF at a few hundred volts. Select one
specifically designed for Strobe and Photoflash applications, these are made with
very low ESR ( Equivalent Series Resistance ). Larger capacitance has lower ESR ,
in the range of interest typically around 0.1 ohm or less. This type can best
provide the firing pulse. Price and sizes vary greatly, shop around.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260350709930 - 2 X $ 35
This one here is 150 Joules in 100 cc ~ ( 40 X 80 mm )
' C ' - Electrolytic Power Capacitor - 1500 uf 450 VDC - $ 5 , salvaged
* * Marx Generator made up of 10 of these = 1500 Joules
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=140322028747
* Note if this auction has ended, scroll down to the original offer and
. . select " View seller's other items ". This offer is regularly repeated.
Observe dummy terminal pinout-code VRD pg 13(pdf) , guidelines pg 19 , 20 , 21, (pdf)
http://www.chemi-con.co.jp/e/catalog/pdf/al-e/al-all-e1001i-090126....
available new from United Chemi-Con Caps - http://www.ucccaps.com
http://www.ucccaps.com/detail.aspx?ID=103647
http://www.ucccaps.com/detail.aspx?ID=105567
Described as " snap mount " usually implies " spade " type terminals for mounting
with spade wire lugs for easy replacement when servicing appliances. These
are not that kind and are best mounted on a board with terminals soldered.
- As we shall see , output of these caps can be doubled to 300 Joules per 100 cc.
_____

Hi Energy Cap
http://www.gaep.com/tech-bulletins/large-high-energy-density-capaci...
Electrolytic Technology & Design
http://www.elna-america.com/tech_al_principles.php
Aluminum Electrolytic Application Guide
http://www.cde.com/catalogs/AEappGUIDE.pdf
Electrolytic Capacitors - Testing, Care & Storage
http://www.jammaboards.com/guides/Capacitor_Testing.pdf
also online here - http://www.repairfaq.org/sam/captest.htm
ESR
http://www.gaep.com/tech-bulletins/capacitor-engineering-bulletins....
http://www.faradnet.com/deeley/book_toc.htm
Capacitor Service Life
http://www.liebert.com/common/ViewDocument.aspx?id=1210

These electrolytics are polar and cannot stand reverse bias , but can be discharged while
connected in series aiding , providing there is a diode ' D ' parallel , serving to prevent
reverse charging as described before. This is the most expensive item of the circuit selling
for 30 to 55 dollars U.S. A 600 volt 300 amp ( or better ) chassis mount stud type Diode
with flag terminal. one of this -> ' D ' Stud Diode - ( 300 amp - 600 volt ) - $ 30.44
http://www.mouser.com/Search/Refine.aspx?Keyword=844-300UR60A
http://www.vishay.com/docs/93508/93508300.pdf
http://sigma.octopart.com/12038/datasheet/Vishay-300UR60A.pdf, similar to these
[url][/url][url][/url]
A diode of lesser current rating ( and therefore cheaper ) can withstand
brief surges , but it won't last for very long through repeated firings of this type.
Alternatively several cheaper lesser rated diodes may be used in parallel , for example ,
4 of these -> ' D ' Stud Diode (SDI) 70HF40 - ( 70 amp, 400 volt ) - $ 0.50 cents salvaged
for anything higher than it's 400 volt rating , 2 in series 4 times , 8 total.
look down near the bottom , use the " find on this page " function of your browser
http://www.surplussales.com/Semiconductors/Diodes-Rectifiers-3.html
http://sigma.octopart.com/511589/datasheet/Vishay-70HF40.pdf
or 3 of these -> ' D ' Stud Diode - ( 95 amp - 800 volt ) - $ 6.82
http://www.mouser.com/Search/Refine.aspx?Keyword=844-95PF80
http://www.vishay.com/docs/93532/93532.pdf
General information on diodes.
http://www.kilowattclassroom.com/Archive/DiodeRec.pdf
_____

The seller of the 1500 uF cap listed above , correctly observes that 10 of those
arranged into a Marx generator , ( a device to charge caps in parallel and then discharge
them together in series ) will produce a 4500 volt output ( 450 volts each, times 10 ) but
at only 150 uF equivalent capacitance ( 1500 uF / 10 ) for a total 1500 Joules.
http://www.allaboutcircuits.com/vol_1/chpt_13/4.html
http://home.earthlink.net/%7Ejimlux/hv/marx.htm
http://www.kronjaeger.com/hv/hv/src/marx/index.html
http://www.electricstuff.co.uk/marxgen.htm
Greinacher Cascade Multiplier _
http://www.instructables.com/id/High_Voltage_Power_Supply_For_Marx_...
see parts (CFP) YE-TW-3 and (CFP) YE-TW-6 , here _
http://www.surplussales.com/Capacitors/motorstart.html
http://www.techlib.com/files/voltmult.pdf
http://www.amazing1.com/download/MARXIU1045.pdf
http://www.celnav.de/hv/hv3.htm
http://www.celnav.de/hv/hv4.htm
Here is a real big one ->http://skyfi.org.ru/photos/2008/marksgen/005.jpg
http://skyfi.org.ru/photos/?path=marksgen


Drawing ' I ' shows this with just 4 caps , gaps and diodes in place of resistors,
( anyone of the already outlined charging circuits can be used here )
switch ' S ' flows current through resistance ' R ', and parallel resistor ' r '
with series light emitting diode ' LED ', up diode ' dx ', into ' Mid ' conductor,
through diodes ' d1 ' collecting in the negative ( - ) terminals of capacitors ' C ',
displacing current out of the positive ( + ) terminals flowing through diodes ' d2 '
and out diodes ' dy , dz ' into ' Bot ' conductor back to the a.c. source.
( one 600 volt diode as ' dx , dy ' in line , per every 3 capacitors to resist reverse breakdown
during firing if caps are charged at just a.c line voltage , add more diodes as needed if caps are
charged at higher voltage and substitute spark gaps for the gas gaps ).
As it is charged , light emitting diode ' LED ' momentarily flickers on then darkens
indicating that charging has occurred ( this is also necessary to protect the small diodes
from excessive current when charging starts ). The charging circuit is to be switched off
F I R S T before the charged circuit can be fired. A normally open switch
accomplishes that.

Circuit breaker ' X ' fires the circuit by applying the a.c. line voltage in series with
the caps ' C '. Current is drawn back through ' Mid ' conductor from the
negative ( - ) terminal of the left cap ' C ' which arcs into conduction the left Gas Gap ' gg ' ,
in an avalanche cascade , current surges from the negative ( - ) terminals of all caps
' C ' across Gas Gaps ' gg ' into the positive ( + ) terminals of cap(s) ' C '
to arc into conduction Spark Gap ' G ' where from current surges into the positive ( + )
terminal of the right cap ' C '. ' Top ' conductor channels the resulting current surge
to the a.c. source down shunt diodes ' D1 , D2 ' in series to resist reverse brealdown
during firing.

______

Given the example of the 1500 uF 450 Volt cap , it can be charged at 3 times the
peak domestic U.S. a.c. value of 162 volts (* 115 volts X √2 ) to 486 volts ( note
that overcharging slightly ~ 8.5 % is perfectly alright providing it is discharged
promptly and since it is static and not subjected to cyclical deep discharge at
a.c. line frequency which will cause overheating and breakdown failure ).
Voltage of the ten caps ( 10 X 486 ) + 162 peak a.c. line voltage add to 5022 volts
By E = CV^2/ 2 , E = Joules , C = farads , V = volts
1891 Joules = (.00015 F X 5022 X 5022 ) / 2 , , or as Dirty Harry ( Clint Eastwood ) would say
- " will blow your head clean off " - , this is not an exaggeration , 1891 Joules is equivalent to
1395 foot pounds of muzzle energy , a proof load for the .44 caliber remington magnum ,
and nearly the equal of the large heavy power cap shown above.
Loud blowing up of fruit http://www.youtube.com/watch?v=aWf-V2-kr9Q
Here is what happens with 9 kJ - equivalent to a .50 caliber Browning Machine Gun round.
from http://www.powerlabs.org
Just think , that could be you all over the street.


9kJ is what a hair blower/dryer consumes in only six seconds The short time interval
of the pulse makes all the difference. Read Overview here _
http://en.wikipedia.org/wiki/Pulsed_power

- This is continued in the following post -

___________________________________________

- continued from the post above -

Available again - Get'em while they last !

' C ' - Electrolytic Power Capacitor - 1500 uf 450 VDC , 150 Joules in 100 cc ~ ( 40 X 80 mm )
- $ 5 , salvaged -> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=14033...



.

@ 12AX7

See the detailed explanation in the opening post a bit down from the top
where it says Joules needed for vaporization of a 2 cm 28 AWG wire
on how to determine the joules needed to blow the volume of metal
comprising a bridgewire. You can calculate the weight with this _
http://circuitcalculator.com/wordpress/2007/09/20/wire-param...

Knowing this you can now proceed to the next phase , of determining
the capacitance and voltage to provide the needed energy

You stated
~ 4 Joules = {( 20 uf ) X ( 630 volts ) X ( 630 volts )} / 2

10 Joules at 1000 volts is not realistic , if the rating is
substantially exceeded the caps will fail , count on it.

Of course you can get around this by placing 2 caps in series
to withstand 2 X 630 volts. The energy will remain ~ 4 joules
for the reduced equivalent capacitance of 5 uf
Discharge time will not change , although the actual output
certainly will be less. Read my third post above for why that is.

The ESR ( Equivalent Series Resistance ) of the capacitor(s) determines
what the discharge time will be. By your numbers the ' RC ' time constant
has to be (.003 ohm ) X (.00002 farad ) = 60 nanoseconds , where 2.3
microseconds comes from I don't see.
If you don't know or have a ' reasonable ' idea of what the ESR
is ( from the manufacturer perhaps ) any ' surmise ' of a discharge
time is just that, surmise.

Voltage is irrelevant to anything but the determination of what
the energy of the capacitance is. Higher voltage will only squash
more of the energy into the leading part of the discharge profile.
For the established ESR the pulse width remains unchanged
regardless of any other changes. A higher energy pulse may be
inferred from the truncated leading portion from what follows.

Extremely short ( a few millionths of a second ) discharge times
unless there is some other need besides just exploding a wire, is
wholly uncalled for and unnecessary.
A very big problem which rears up with short discharge times is
the skin effect which overshadows any stray inductance by at
least another 2 orders of magnitude. ( 100 times or greater )

You cite 2.3 usec ( I'll humor you for the moment )
frequency is the reciprocal of time , f = 1/ t , then the 2.3 millionths of a second
translates to a frequency of 435 kHz. You will need at the very
least a 32 AWG wire or much preferably smaller to lessen attenuation
of the pulse.
See this chart - http://www.powerstream.com/Wire_Size.htm
posted just above this - Joules needed for vaporization of a 2 cm 28 AWG wire
or calculate it here yourself _
http://www.mantaro.com/resources/impedance_calculator.htm#sk...
also attached below _


True all of this is classic EBW technology and practice. The prevailing
school of thought is a minute EBW subjected to a very brief pulse, which
serves as a choke point to the pulse, thereby condensing the energy.
The problems with this is that it requires very careful engineering with
no ' wiggle ' room. If something is off by just a bit due to unforeseen
parasitic losses , either because of lowered voltage reducing the needed
energy, or stray inductance sapping it, then there is no bang.

In my view and the point of starting this thread is that everything
is wrong with this established approach and that it may work at all
is a wonder.

.

Quote: Originally posted by franklyn

You stated ~ 4 Joules = {( 20 uf ) X ( 630 volts ) X ( 630 volts )} / 2 10 Joules at 1000 volts is not realistic , if the rating is substantially exceeded the caps will fail , count on it.

@ 12AX7

@ Hennig Brand

Quote: Originally posted by franklyn

The physics of this are , ESR will determine the time constant

Quote: Originally posted by 12AX7

And inductance simply doesn't matter? I ask again, are you able to suspend Ampere's law at will?

Hello,

Paper here (my favourite communication tool as it gives the impression I actually know WTF they are saying ).

What is the length (approx.) time period involved when we declare that an EBW is actually able to detonate secondary explosives? (assuming we have enough Joules in that time period). There must be some (approx. ballpark) time period where time greater that this maximum period are considered simple too slow no matter that the pulse energy.

From the paper (it's about making nano powders and has pulse times in the order of 2 to 4 micro seconds) there is a graph below and some text. It is a worthwhile read.

_________________________________________
The copper wires used in our experiment are 196 micro m in
diameter and 85 mm in length, which yields an equivalent
inductance of 0.11 micro H calculated using Eq. (1). Figure 2 presents
the waveforms of the discharge current and voltage
measured in the experiment in which the energy storage
capacitor was charged to a voltage of 20 kV. It shows a
typical picture of exploding wire. The voltage begins to
rise strongly when the current reaches its maximum of
about 10 kA and then falls down, which means that the
vaporization of the wire begins, leading to a rapid increase
of the wire resistance. After the current falls down to a
value of 3 kA, it rises up again, which represents an arc
breakdown through the wire vapor, a shunting of the
current by this low resistance arc.
It should be noted that the experimentally measured
voltage shown in Figure 2 is not the voltage of the wire resistance
but rather the voltage across L2 and R2 in addition to the
wire voltage. The voltage of the wire resistance is important
for us to make an estimation of the energy deposition in the
wire before the explosion.
__________________________________________
Fig 2 below. L2 and R2 are the resistance and Inductance of leads inside vacuum chamber (unavoidable).



[Edited on 11-7-2009 by dann2]

Quote: Originally posted by franklyn

a short pulse only matters if you need high precision in timing a pulse

Quote: Originally posted by Hennig Brand

I am starting to think that it is pretty difficult to tell exactly what is taking place in this EBW senario, even with a good command of the electronics laws. Even normal electronics, at slower speeds etc, is studied mostly by looking at the effects of things changing that we can see, or using relatively simple instruments(except maybe by high level people).

Referring, perhaps, to an oscilloscope? Those are fairly standard equipment, and a must-have even for mere repair techs. I wouldn't at all consider a 'scope "high level".

You can get a fair base model DSO (that's Digital Storage Oscilloscope) for $500 or so new, or a better, older one for $100 on eBay pretty easy. You pretty well need a DSO for this, since you only get one shot of waveform, kind of hard to observe on a live analog scope (although they did make analog storage scopes!).

Quote: Originally posted by franklyn

Pulse width is irrelevant to whether explosion occurs or not. Pulse amplitude is what matters since the area under the power curve is the energy delivered. Knowing what energy is necessary to make vapor of a known amount of metal , it is then a matter of delivering that in excess.

Quote: Originally posted by dann2

According the manufacturers they use Gold as it is very stable for years

Quote: Originally posted by franklyn

Inductance matters to what ? The time constant chart above _ http://i41.tinypic.com/35mgob5.jpg is the same for RC as it is for L/R. You either have one or the other not both together.

Quote: Originally posted by Hennig Brand

I just took some 40gauge wire(0.0799mm diameter) and made a bridge of approx 5mm length(arbitrarily). I used one of those $2-3 racket bug zappers to charge up my 25uF(oil filled) cap to 600 volts, giving me about 4joules in first 1.5 time constant(1.25usec).

@ watson.fawkes

" According to your argument, it doesn't matter at all how long it takes to
deliver the excess of energy."
I made no such argument , you're just not heeding the point that power
is all what matters. All this I explained at the head of this thread.

Requirements in your short pulse scheme are kilovolts producing kiloamps
to generate megawatt power pulses , fine.
Go to your local utility power station and hook up a wire to ground and
touch the other end to one of the multi megawatt power lines.
What is the pulse width of that ?

It will be whatever the EBW says for whatever power the EBW will admit.
It is unavailing to provide much power beyond a reliable margin or contrive
to cram it in excess. You can have megawatts on tap without resorting to
kilovolt short pulses. You just don't understand , and worse you won't listen
that you don't understand. Kilovolts and short pulse widths are inane and
unnecessary.


@ 1 2 A X 7

Round and round we go , where we wind up nobody knows

I will say this , you make sweeping statements without citing any references
that detail the model of capacitive discharge which as yet you have not
communicated with any coherence here.
It appears that you insist that RC time is really ( R + XL ) C time.
( XL being Inductive reactance ) Cite one source or reference that affirms
or states this.

60 nanosec times 5 is the textbook expected discharge time ~ 0.3 usec
this is off about 10 times from your measurement using an undisclosed
test setup of your DUT ( Device Under Test ) a monolithic capacitance
made up of 200 individual pieces the self healing film of each supposedly
has not been impaired by the latent heat of soldering.
ESL is about 1.6 nH per millimetre of distance along the leads which
connect each cap to the rest. Which likely accounts for your measurment.

I cited this near the end of the 2 nd post here as an example of what you
seem to favor - http://www.amazing1.com/download/MARXIU1045.pdf
No where does there appear any mention of induction , though clearly
from the size of the circuit path and current produced , it must be
considerable. So what. The discharge has already occured
when the induction appears. You have heard of Kirchhoff.

__________



My model for a circuit is a AA battery with a slightly longer length of wire
coming from one end touching a light bulb pressed to the opposite end.
The battery has internal resistance and that of the light bulb increases
greatly when lit.
Now substitute a capacitor for the battery and the EBW for the light bulb.
The only difference is in the time frame each circuit runs.
The energy stored in the capacitor discharges as the voltage drops to
near nothing. As this happens current rises from zero to a maximum.
If the conductor layout is arranged to minimize inductance , little energy will
comprise the induction and most will just heat the entire circuit according to
( I x I x R ). Induction does nothing except retard the current rise time and
affect the phase angle by its reactance. If the capacitor is a non-polar type,
energy in excess of what has been depleted in the circuit resistance during
the first pass will accumulate again in the capacitor charging it in reverse
polarity. This is due to energy from colapse of the small induction, and will
only occur if the EBW remains intact. Hope that clears things up for you.

.

Quote: Originally posted by franklyn

you're just not heeding the point that power is all what matters. All this I explained at the head of this thread.

Quote: Originally posted by franklyn

If the conductor layout is arranged to minimize inductance, little energy will comprise the induction and most will just heat the entire circuit

Quote: Originally posted by 12AX7

Optimally, resistance in the EBW and connections should match the LC impedance, which is Z = sqrt(L/C). If this cannot be obtained, you'll have to settle for oscillations.

Hello,
Two papers attached that may be worth reading.


@Franken
Quote:
..............
Go to your local utility power station and hook up a wire to ground and
touch the other end to one of the multi megawatt power lines.
What is the pulse width of that ?
..........................

Are you suggesting that this will initiate RDX etc.?
To give a lay ladies slant on the thing
The 'pulse length' (in this setup) you will get could be very crudely approximated by the first hump of the 60Hz sine wave that the wire will see. Thats in the order of 8300 mirco seconds. That is paint-drying-speed compared to what has to be achieved in a proper exploding wire bridge for use in a detonator to initiate secondary high explosives (RDX, PETN).
You will get a great big impressive looking mess ('explosion') but not a fast, sharp, sweet (whatever you like to call it) and powerful enough pulse to initiate RDX etc. To use another analogy, you are comparing a large quantity of gun powder being set off to a small amount of (say) RDX going off. A slow electrical discharge (perhaps very 'powerful') is of no use to us. It will literally push or burn off the RDX/PETN and not make it detonate.
With regards to gettng a very fast pulse of high amplitude current out of a capacitor, a similarish statement that was made during a US election fits well here.

It's the inductance stupid.

Unless the capacitor(s) are constructed to have low inherent inductance you will not be getting the current out of it in a time frame small enough for our task.
Too much inertia (inductance) in a capacitor is like a very large powerful compressed spring (the capacitor) that is far too heavy (too much inertia) to respond quickly after release because it is constructed from a material/method that makes it inherently too heavy for the job at hand. It just ain't 'sweet' enough.
This stuff in easier on the brain than those differential equations.....................or do we need the Paul Simon and Caribunkle

Dann2


[Edited on 14-7-2009 by dann2]

Attachment: energy-storage-capacitors.zip (552kB)
This file has been downloaded 585 times

@ watson.fawkes

Quote: Originally posted by franklyn

You may have lost respect for me as you put it , but you do not appreciate the Howl I'm having at your expense. I keep asking myself you guys ( 12AX7 and his fetish for induction ) actually took tests in school - and passed.

Listen Folks,


He's only taking the piss.
Posts under quite a few entites, comes onto a subject and (for some unfathomable reason) starts to talk bullshit (quite subtly sometimes) and them spends post after post after post after post after post taking the piss.
He IS having a howl (via taking the piss).
Take a lesson from Dann2, (I am not giving a lecture here as I'v been there for quite a few tit for tat post exchange much to the annoyance of many I am sure, and had a howl, I'm sure he had one as well) and stop feeding the little monster.

"I wonder, what are your credentials? Have you even taken an electronics class?"

It's not relevant. The Lady in question may have half a dozen electronics related PhD'S.
You know what they say about educating a fool. You end up with a bigger fool.

Regards,
Shadowwarrior Four Four Four.
At the end of the day you never know who you are actually toing and frowing with on the board. If the info. is good or HONESTLY incorrect it's good conversation well worth having. If it's (well thought out) shit you have to hope you can winnow it from the good stuff.
All make mistakes, have misundertandings etc etc, but Benjamin is just systematically taking the piss.


It's the inductance stupid.

You cannot get a reasonably rated capacitor for our job to empty quick enough into the load unless it has been specifically designed to have very low inherent inductance. The simple RC model is of no use, as the current rise we need is hugh and tiny inductances (that are 'usually' ignored) become the elephant in the capacitor. [Insert howl here or trumpeting sound would do too :cool

GOOD NIGHT


[Edited on 14-7-2009 by dann2]

Another edit.
Heck, Perhaps I should say taking the Hissss (wink)



[Edited on 14-7-2009 by dann2]

@ 1 2 A X 7 , damn2

The personal slight to 12AX7 by damn 2 is not called for. Personally I find the
jibes a challenge and a test of the validity of my assertions and forces me to
think. I have to admit that I have been unheeding of the critique made and it
turns out to have been warranted.
I have experienced the revelation that , AH HA moment when one realizes
yes I see now.
I was looking online for an unimpeachable reference that is not suspect , to
affirm my contention that induction is not relevant in the analysis of an RC circuit.
http://hyperphysics.phy-astr.gsu.edu/HBASE/electric/capdis.h...
Discharge is described simply by ohms law showing the curve for both voltage
and current in phase , diminishing together.
I was affirming this notion when It occurred to me what's wrong with this picture.
The problem is that it is an idealization and quite wrong as a representation of
what actually occurs. The picture shows both voltage and current diminishing
while I'm contradicting myself in the same sentence describing the current
rising at the start of discharge - which it does , 180 º out of phase !

!2AX7 called it right.
By Ampere we know that current produces a magnetic field ( Biot - Savart )
Energy goes into the induction ( current rise ) and delays the onset of peak
power and current. Because a pulse is so brief , this phase shift can lower the
power available in circuit ( product of voltge and current ) to the extent it can
affect performance.
I recall a similar exchange with Rosco Bodine debating power line conditioning.
http://www.sciencemadness.org/talk/viewthread.php?tid=9064#p...

The attached - gif - is a graphed profile of the current , voltage and power curves
as they must appear in a real circuit on discharge of a capacitor. Voltage drops
from time zero to full discharge ( 5 X R X C ). Current in the meantime first rises
at some rate determined by the inductance value of the WHOLE circuit , to a
maximum value which must be less than it would be if the decline had coincided
with the voltage , because some energy has gone into the induction instead.
The power curve is the blue peripheral line of the light blue region which represents
the total energy of the discharge. The peak of the power curve occurs where
voltage and current curves cross having equal amplitude and drops off on either
side. Practically this is what can be considered the ' Pulse '. The energy
( light blue area ) is all there is , if it is sapped by inductive reactance in the circuit
the amplitude is reduced ( attenuated ) and less of the energy is available to the
resistance of the circuit where the shortfall can critically affect the performance.

Item 1 of the next attachment shows an idealized pulse with a steep leading slope
( it can never be verticle ) trailing off to zero some time after. Item 2 shows
a realistic pulse with a sloping leading edge attributable to circuit inductance.
Note that both areas are the same ( only the profiles differ ) because the energy
remains the same. Item 3shows extreme delay in the current rise time and a
marked reduction in amplitude ( height ). The area ( energy ) remains the same
since this remains the amount the capacitor discharges, but the pulse has now
become wider.
Note that in this actual oscilloscope trace posted by damn2 an earlier post
http://www.sciencemadness.org/talk/files.php?pid=157260&...
the current profile is exactly alike.

.

Actually, the voltage waveform is, as I mentioned earlier, either of the form
A * exp(-alpha*t)
or
A * exp(-alpha*t) * sin(omega*t)
and the corresponding current waveform is
B * t * exp(-alpha*t)
or etc.

Attached is a representative plot of the current waveform. The peak reaches a value of 1/e and FWHA is about 2 units across.

Notice that it is continuous, not discontinuous as the plot you found shows. With nothing in the circuit changing over time, nor any nonlinear elements in the circuit, it cannot possibly be discontinuous -- something which is fundamentally at odds with the other curves included, anyway.

Much more than you could ever want to know about this simple phenomena can be found in even a rather bad EE textbook -- I'm sure you can find one of more than sufficient quality at the local library, or find some articles on the IEEE.

Tim



[Edited on 7-17-2009 by 12AX7]

Quote: Originally posted by 12AX7

Notice that it is continuous, not discontinuous as the plot you found shows.

@ 1 2 A X 7

Simple harmonic oscillation , whether damped or not , is barely a descriptor
of this circuit. To have oscillation you must first have a circuit, a condition
which in this case disappears immediately after it is turned on. Waveforms
describe voltage or current of energy storing circuit elements. The series RCL
circuit has 2 so it is a 2nd order circuit characterised by a sinusoid which is
a superposition of 2 other waveforms , either 2 sinusoids or an exponential
and ramp or 2 exponentials.
As the capacitor is discharged the step response waveform is practically a
DC current transient. The pulse comprises the energy occuring before and
immediately following the the peak power point as I have already described.
Resistance of the EBW will increase to a level comparable to that of an
incandescent lamp , becoming most of the resistance value of the circuit,
effectively consuming available power and damping any reactive component
response. A moot consequence since it is all done and overwith before the
capacitor has even entirely discharged and therefore before even the onset
of peak current. Horizontal scale is arbitrary , still the shark fin profile of the
current waveform is what you expect as conduction is switched off by the
now exploded EBW.

Discontinuous is a mathematical term denoting a break in the curve being
graphed, where the line ends and continues again at some level above or
below. http://mathworld.wolfram.com/Discontinuity.html
Current and voltage can only change in a continuous way at all times.
http://mathworld.wolfram.com/ContinuouslyDifferentiableFunct...
A discontinuous change means that energy has appeared or vanished with
no change in time. Since power is the derivative ( slope , or rate of change
of energy ) this implies infinite power , a condition which cannot be real.
This is similar to attempting to divide by zero.
http://mathworld.wolfram.com/Tangent.html
Note the line may instead change direction at some point indicating a change
or substitution of the initial depicted expression. This is piecewise continuous
http://mathworld.wolfram.com/PiecewiseContinuous.html , similar to a
compound curve ( one comprised of two joined differently formulated curves )
except the two expressions forming the composite line are not differentiable
where they join , said not to be "well behaved ". An example expression that
is not well behaved is a fractal , which is continuous but too jagged to be
describable using calculus. The superposition ( adding of expressions ) which
are individually curvilinear can also give rise to a composite pointed line.
See pdf page 4 of attachment - Analysis and Design of Linear Circuits ,
Zero State Response - pg 413

The step condition ( applying and removing power ) matters. Relaxation
oscillators and power controls employing SCR's most commonly exhibit this.
Pulse width modulation as it's called , is basic in power control electronics,
and the basis of Switch mode power supplies.
Relaxation oscillator
http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/relaxo.html
http://en.wikipedia.org/wiki/Phase_control


" the transient solution has been solved millions of times by students "
Cetainly not from what explanation you have given. Succintly and clearly stated here
http://www.coilgun.info/theoryinductors/dampedoscillator.htm

For those who may care ,
I dusted off an introductory text from my college years.
The Analysis and Design of Linear Circuits - Roland E. Thomas & Albert J. Rosa , 1994
ISBN - 0 - 13 - 220005 - 8
copied the relevant pages including the derivation of applicable expressions.
This is attached below in the second PDF. The first PDF is more brief and concise.

Available online , I recommend this one _
Transient Analysis of Electric Power Circuits Handbook
http://rapidshare.com/files/12045279/EBC_transient_analysis_of_electric_power_circuits_handbook-ISBN10-0387287973.rar
RCL analysis is on book pages 113 , 135 , 143 , or pdf pages , 127 , 149 , 157

_____________________________________________________________
Now that everybody's eyes have glazed over I ask myself what incisive
insight has this assertion of 12AX7 lent to the present inquiry if any.
The only meaningful contribution to the depiction of discharge is that at
the start T= 0 the voltage curve as it appears in the 1st gif shown below ,
(figure 8.27 , from pg 437 )The Analysis and Design of Linear Circuits
does not drop straight down and curve away as it does if only considered as an
R C discharge , seen for comparison in the 2nd gif attached alongside below.
It is instead rounded sinusoid at the top , because inductance impedes discharge
( superposition of 2 waveforms ). So the onset of discharge , as I had already
stated before , is very slightly delayed , to which 12AX7 adamantly exclaims ,
" Blatantly wrong ! please read up on RCL series resonance ".

Even at the rather extreme value of inductance of the cited textbook example,
1 Henry , the effect of inductive reactance is minor , considering the power
pulse will occur before T = 1. The range of resistance determining what damping
may occur shrinks to inconsequencial considering the EBW resistance rises from
negligeable to hundreds of times the total circuit resistance. This makes
nonsense out of any result from plugging static circuit values as constants into
a resonant circuit formula. The curve suggested describing the current , may well
do so and will terminate somewhere before it reaches its peak value.
What does it matter what might appear after ( providing a circuit still remained )

Even in other applications of pulse power , with a shunting " Fly-Back " diode
parallel with the capacitor so that reverse charging cannot occur ( known as
" free wheeling " ) there cannot be oscillation anyway , damped or otherwise.
In such case an undamped circuit prevails since current drops to zero before
the critically damped condition when current normally most quickly goes to zero.

The 3rd gif attached below shows the effect of damping on a circuit. Omega ( ωd )
the resonant frequency in radians 1 /√LC is constant. The damping coefficient
Alpha ( α ) = R /2L varies. Since inductance ( L ) is common to both the only
thing which varies is ( R ). Increasing resistance R reduces amplitude height.
Because all have the same height this implies the voltage is being raised as
well. Only at extreme Resistance R is some minimal delay apparent of the peak
power point , indicated by a verticle red line always ahead of the peak current
marked in green.__________________________________________________


Some other resources available online
http://www.physics.uoguelph.ca/~leblanc/phys2470/labs/transients.pd...
Module 3 , Lesson 10 - RL , CL
http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT%20Kharagpur/Basic%20Electrical%20Technology/pdf/L-10(GDR)(ET)%20((EE)NPTEL).pdf
Module 3 , Lesson 11 - RCL
http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT%20Kharagpur/Basic%20Electrical%20Technology/pdf/L-11(GDR)(ET)%20((EE)NPTEL).pdf

Attachment: R C L Transients Electrical Technology.pdf (248kB)
This file has been downloaded 895 times

Attachment: Analysis and Design of Linear Circuits.pdf (1.7MB)
This file has been downloaded 841 times

@ damn2

scroll down to see fig 14 , and read that following paragraph
http://[/color]sound.westhost.com/articles/capacitors.htm
Described is the performance of the sort of capacitor I favor.
The graphed profile is seen in the attached RCL simulation gif below
This execellent RCL calculator allows you to determine circuit parameters
by simply varying component values rather than mathematically plotting
their graphs. http://[/color]www.coilgun.info/mark2/rlcsim.htm
The slider bars value scale is checked up or down at the top the chosen
value is indicated below each one and along the top of the graph window.
According to the author the scales for C & L are graduated in uF & mH
but I find micro-microFarad a confusing term for pico farad and the same
with calling a Farad , Mega-microFarads.

As it is with ESR, so it is with ESL ( Equivalent series inductance ).
Resonant frequency remains unchanged for capacitors in parallel because
the inductance of individual caps does not change. Inductances in parallel
just as resistors in parallel, the equivalent inductance is greatly diminished.
Since capacitance adds together , the product with inductance remains the
same, and so does resonant frequency. There is no conflict with the RC time
constant. Just as resistors in parallel, ESR of caps in parallel is also greatly
diminished , since capacitance adds together , the product with resistance
remains the same , and so does the RC time. Whether one cap or many of
the same type in parallel , the resonant low impedance point of a whole
bank is the same as for one capacitor, provided the connecting bus is a low
inductance as the rest of the transmission line.
Actual caoacitance value of electrolytic types varies + / - 10 % at least
so the response of several acting together is their average value.

Regarding
http://www.sciencemadness.org/talk/viewthread.php?tid=12414&...
It is not useful when current and voltage switch polarity and have zero value.
This then is a problem of commutation, easily solved by having an SCR trigger
a Trigatron into conduction in series with the EBW , at or near peak line voltage.
Forget alternations , think of this as a DC source during a short time interval.
If you believe any small wire will respond with only a fizzle you must buy your
wire in some other universe.

High performance capacitors
http://[/color]www.sbelectronics.com/power_ring_division/new_laser_pulse_power.html

Yes when I can , I do read _

1. Exploding Wires Volume 1 , Chace, W. G. - Moore, H. K. , 373 pages , Plenum , 1959 ( out of print )
2. Exploding Wires Volume 2 , Chace, W. G. - Moore, H. K. , 321 pages , Plenum , 1962 ( out of print )
3. Exploding Wires Volume 3 , Chace, W. G. - Moore, H. K. , 410 pages , Plenum , 1964 ( out of print )
4. Exploding Wires Volume 4 , Chace, W. G. - Moore, H. K. , 348 pages , Plenum , 1967 (- in print -)
- http://[/color]www.dtic.mil/srch/doc?collection=t3&id=AD0759669 - see distribution statement at bottom
5. The Generation of High Magnetic Fields , Parkinson, David H. - Mulhall, Brian E. , 165 pages , Plenum , 1967 ( out of print )
6. Pulsed High Magnetic Fields; Physical Effects & Generation , Knoepfel, H. , 372 pages , Elsevier , 1970 ( out of print )
7. High Speed Pulse Technology Volume 3 , Capacitor Discharge Engineering , Frungel, F. , 498 pages , Academic Press , 1976 ( out of print )
8. Megagauss Technology and Pulsed Power Applications , Fowler, C. M. - Caird, Erickson , 879 pages , Plenum , 1987 ( out of print )
9. High Power Switching , Vitkovitsky, Ihor , 304 pages , Van Nostrand Reinhold , 1987 ( out of print )
10. High Power Electronics , Sarjeant, W. J. - Dollinger, Richard E. , 392 pages , Tab Professional & Reference Books , 1989 ( out of print )
11. Gas Discharge Closing Switches , Schaefer, Gerhard , 569 pages , Plenum , 1991 (out of print)
12. Introduction to High Power Pulse Technology , Pai, S. T - Zhang, Q. , 307 pages , World Scientific , 1995 ( out of print )
13. J. C. Martin on Pulsed Power , Martin, T. H. , et al , 546 pages , Plenum , 1996 ( out of print )
14. Fields & Transients in Superhigh Pulse Current Devices , Shneerson, G. A. , 561 pages , Nova Science , 1997 ( out of print )
15. Pulsed Power , Mesyats, Gennady A. , 568 pages , Springer , 2004 ISBN 0306486531 (- in print -)
-
16. Exploding Wire Detonators: Resistivity Functions and Initiation Criteria for Circuit Calculations , Blackburn, J. H. , Muller, G. M. , CR-69-3201 , June 1959
17. Detonator Circuit Calculations:Resistivity Functions , Blackburn, J. H. , Muller, G. M. , OC-CR-68 , May 1958
18. A Theoretical Model of the Resistance Behavior of Exploding Wires , Tucker, T. J. , OC-RR-71 0739 , January 1972
_ _ _ _ _ _ _ _ _ _ _ _

I'll see you , and raise _

Scaling Underwater Exploding Wires
http://handle.dtic.mil/100.2/AD633115 , This redirects to the next link below
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD633115&Location=U2&am...

EBW1 - a computer code for the prediction of the behavior of electrical circuits containing exploding wire elements
http://http://www.osti.gov/energycitations/servlets/purl/4229184-1IbmTb

Formation & Evolution of Plasmas from Single Exploding Wires
http://http://www.prod.sandia.gov/cgi-bin/techlib/access-control.pl/2002/0...

This one is just ridiculus _
Exploding Wire Initiation
http://http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19690013624_1969013624.pdf
Read last paragraph of ' General system description ' page 2 , note the time scale for discharge.

Oscillographic & Schlieren-streak Photographic Investigations of an Exploding Wire Discharge
http://http://www.physics.re.kr/resource/wop.pdf/J01/1984/017/R02/J0119840...

Round and around we ..................

Hello,

Holy moses Sir Frequelin. I am not going to read all that!!!!!!!!!!!!!!!!
I hope you have learned (from your not inconsiderable reading splurge) that you need a low (not you average electrolythic or even a 'photographic flash tube electrolythic') inductance capacitor in an exploding-wire-set-up, when you want a wire to explode in such a fashion that it will also initiate a secondary explosive (RDX, PETN seem to be the one's that are used) placed in very close proximity to it.
It's the econony inductance stupid, sums it up well for me. Most of that problem inductance is in you average capacitor. Of course you need low ESR and proper feed wires/lines etc but the internal inductance in the capacitor is our biggest problem for ultimate dumping of the cacpacitors energy into where we want to get it in a suitable short time frame
BTW, I did not read all that (hopefully helpful for yourself) reading stuff that I suggested you should read. Just posted a few bits of it in some post or other above. You were argueing along the lines of:
It's not the inductance stupid, inductance (in the capacitor) is not relevent etc etc, which is simple wrong.
Your posts are very verbose!!!!!!!!

dame2 out, over to dame1

Dann2
]

[Edited on 2-8-2009 by dann2]

Quote: Originally posted by franklyn

Current and voltage can only change in a continuous way at all times. [...] A discontinuous change means that energy has appeared or vanished with no change in time.

Quote: Originally posted by watson.fawkes

I would recommend that anybody reading this completely ignore anything franklyn has to say about mathematics.

It has been said by someone here that this is a scientific discussion.
Well , no , it's an engineering discussion , at least it is so for me.
Quoted here from the introduction to chapter 9 of the same text book
referenced futher up on circuit analysis.

The Analysis and Design of Linear Circuits

" LaPlace transforms have their roots in the pioneering work of the
Victorian British engineer Oliver Heaviside (1850-1925).
His operational calculus was essentially a collection of intuitive rules
that allowed him to formulate and solve a number of the important
technical problems of his day. Heaviside was a practical man with
no interest in mathematical elegance. His intuitive approach drew
bitter criticism from the mathematicians of his day. However,
mathematicians like Thomas John Bromwich and others eventually
recognized the importance of Heaviside's methods and began to
supply the necessary mathematical foundations.
The transformation is named for Laplace because a complete
mathematical development of Heaviside's methods was eventually
found in the 1780 writings of the French mathematician
Pierre Simon Laplace. "

Heaviside originated the terms " Inductance " and " Impedance "

@ watson fawkes

I entirely concur. One should not lend much credence to someone who does
not provide references nor supporting documentation , as if incomprehensible
incoherent double talk can pass for self evident truth. Trouble is, balderdash
like pissing upwind has a way of coming back at you. If credentials matter
at all then you have a bone to pick - not with me - but the authors of the
textbook excerpts I provided whose resumes are on the cover. Attached
additionally are the highlighted relevant passages.

When two Ph.D heads of engineering schools with backgrounds from Stanford ,
and jointly with the U.S. Air Force Academy and the Institute of Electrical and
Electronics Engineers , refute , and by implication indicate that you are full of crap ,
it is very likely to be true. No one can accuse you of heeding the well tested notion ,
it is better to remain silent and have people think that you are not the savant
you pretend to be , than it is to open your mouth and remove all doubt.

.

Attachment: Capacitor Power & Energy pg 342 ch 7.pdf (1.2MB)
This file has been downloaded 826 times

Quote: Originally posted by franklyn

One should not lend much credence to someone who does not provide references nor supporting documentation , as if incomprehensible incoherent double talk can pass for self evident truth.

@ 1 2 A X 7

I'm glad you're finally looking at this as real objects. So what has all that B.S.
over the last 2 pages of this thread meant after all. This is a perfectly sensible
and studied retort to my premise , thank you for that

R C time of the cited 470 uF capacitor , examined alone , is actually 10 times
faster ( 0. 290 ohm ) x ( 0. 000470 , Farad ) = 0. 00013 sec ( 130 microseconds )
this in the upper time range of what is known to produce explosion.
( obviously a whole circuit adds to the values of R & L )

" far too slow " , only in deference to the known way in which these things are
usually done , which is not in dispute. The rise time for current of a billion amps
per second is a well established parameter. This means that in the first nanosecond
there is a 1 amp current , after 2 nanoseconds it has risen to 2 amps by one
microsecond current will be 1000 amps. You will note that this precondition
is well met by the example you give seen in image gif 1. What energy is required
to achieve explosion is then a matter of time and the area beneath the
power curve ( volts X amps , not in view ).

I agree 1.3 millisecond is a long time for an event of this kind , if the energy supplied
is limited. As you point out " to conserve energy, raise voltage " , but then it really
depends on what power level is available wouldn't it. A 1.3 millisecond pulse of the
same high level or nearly so will accomplish the same result. The EBW is not going to
hold off exploding just because it continues receiving power beyond a shorter pulse.

In the gif 2 image 10 capacitors in parallel yield 4700 uf and ESR & ESL drop to 1/10
the value for the bank as a whole from 290 mohm to 29 , and from 20 nH to 2 nH.
The time scale remains unchanged but because the currents of 10 capacitors add
together total current is now 10 times greater and therefore so is the power supplied.

I don't see a problem

" sounds like a rifle ", is not meaningless , it's an indicator. One will at least need to
hear that to warrant further investigation and confirmation. I'm sure no one has
experienced a bridge wire explosion that is quiet , though a fizzle will not be as loud.

___________

Finagling

In image gif 3 inductance is raised to the original 20 nH to better view the whole
graph. R C time is 130 usec , the time for what is the useful pulse is 1.5 R C =
195 usec seen at the right side at the 100 volt level when 95 % of the energy
has discharged. Inductive reactance is only now just noticable as voltage and
ESR remain unchanged , the peak current has dropped from 15.5 kiloamp to 15.2
kiloamp as some energy has instead gone into induction.
In image gif 4 inductance is raised 10 times to 200 nH on a one 290 milliohm
470 uF cap delaying the 1500 amp peak current onset 4 microseconds. Dividing
1500 kiloamps by 4 is 375 , little more than a third of the 1000 amps per usec
rise time required. This is a failure mode for a short pulse scheme. Raising the
voltage compensates for this.
Raising the power by increasing capacitance as in gif 2 will compensate for this
just the same. Dividing 15.5 kiloamps by 4 is 3875 amps , well beyond where the
rise time becomes marginal.

In image gif 5 ESR is reduced to 29 milliohm and the nearly critically damped actual
R C L discharge time is now just 43 usec. R C time ( 0. 029 ohm )
x ( 0. 000470 , Farad ) = 0. 000013 ( 13 microseconds ), times 1.5 is 19.5 usec
just half of the R C L value. The ESR of just 29 milliohm is that of some film or oil
capacitors and with the voltage remaining unchanged the peak current is now
6.6 times greater at 10 kiloamps. Reducing inductance back to 20 nH will also
increase peak current by little more than a third to 13.8 Kiloamp. Doubling the
voltage also doubles the current and will increase the power by 4 times.

By C( V x V ) / 2 , the 10 cap bank is , ( 0. 0047 F) x ( 450 x 450 ) / 2 = 476 Joules
At double the voltage the 470 uF capacitor is , ( 0.00047 F ) x ( 900 x 900 ) / 2 = 190 Joules

Average power for the 10 cap bank is 476 Joules / .000195 sec = 2.4 megawatts
Average power for the 900 volt 470 uF capacitor is 190 Joules / .0000195 sec = 9.7 megawatts

Of course the capacitance can be enlarged all you want. 4 times as many electrolytic
capacitors , a total of 18800 uF will yield equal power output. As already explained the
discharge time remains 195 microseconds. One could instead use 2 times or just 20
parallel capacitors in series with the a.c. powerline ( as initially described in this thread )
to achieve the same power rating at discharge. This would be a discharge of ~ 1974 Joules ,
10 times as much , since the pulse width is 10 times more than the 900 volt capacitor.

___________

Minor issues are that the EPCOS capacitor cited is a filter capacitor and the ESR
at 290 milliohms is somewhat high , rather than the type specific for high current
discharge in strobe and photoflash applications. ESR totals slightly lower with fewer
large capacitors than more smaller ones. Compare the ones on page 8.











[Edited on 5-8-2009 by franklyn]

Pay no attention to the man behind the curtain

' I ' am the all and powerful OZ

says watson.fawkes

" interpreter between the authority and you ".

Interpretive mathematics , that's a good one

As an adept specious prevaricator you have no equal.

looking forward to seeing your " theorems "
published in a peer reviewed journal

.

Quote:
_________________________________________
R C time of the cited 470 uF capacitor , examined alone , is actually 10 times
faster ( 0. 290 ohm ) x ( 0. 000470 , Farad ) = 0. 00013 sec ( 130 microseconds )
this in the upper time range of what is known to produce explosion.
__________________________________________

Where did you get the figure of 130 microsec from and what exactly do you mean by 'explosion'.
If the 'explosion' does not initiate PETN or hopefully RDX then it's not what the thread is about.



Another diva break below. This type of setup will not do the required task, no matter how impressive, loud or funny it may be.

http://www.youtube.com/watch?v=KxeUV7CXrlI

Dann2

[Edited on 5-8-2009 by dann2]

Of all things, I decided to build a high voltage power supply tonight, good for 150-400V at up to 30mA. But this is perfect for charging fairly large capacitors, which invited me to add a xenon flash tube and trigger transformer. So I did.

So I hooked up a rather beefy 20uF film and oil capacitor (probably good for lots of amps, with moderate ESL) to the flash tube, and despite not having a storage scope, I managed to obtain this image:



Setup involves shorting the probe with its ground lead, placing the loop thus formed right near the capacitor terminals, thus capturing some EMI.

Vertical is uncalibrated, since that would be rather hard to do. It should be current, or possibly the derivative. Time is 10µs/div, as shown.

Assuming the tube is a direct short (not a bad assumption, at least for the first 16 microseconds), the discharge looks a lot like a damped sinusoid with pseudoperiod of about 24us. This implies an inductance of 0.73uH. Since it's decaying fairly rapidly (after about 2 cycles), Q = 2 roughly, so resistance is (very roughly) 100 miliohms. I would expect the wiring and capacitor to contribute only a few miliohms, so most of that loss must be in the xenon (good, that means it should be fairly efficient as far as heating up the xenon plasma).



As you can see, these figures are consistent with the respective RLC plot, which bears a striking resemblance to the oscillograph (at least until things change).

After 22us, I think the xenon cooled down enough that ionization slowed down. At this point, terminal voltage must've risen to a fairly constant value (the current magnitude seems to fall linearly). As the plasma continued to cool, voltage and current decayed exponentially with time, resulting in the ~40us tail seen after the main transient.

I'm not sure how much charge was left in the cap after a shot, maybe 30V. My supply has bleeder resistors, so I didn't measure it.

Incidentially, this 1.6J shot seems to have about enough dI/dt and speed to fire the kinds of things talked about in this thread. Interesting to find out what an electrolytic will do.

Tim

Quote: Originally posted by dann2

Hello, Attached patent using no wire, just a spark gap. Time of discharge in the order of a few micro seconds. EDIT. I bit strange, the patent is dated 1976 and it was filed in 1950? Misprint I suppose Dann2 [Edited on 5-8-2009 by dann2]

@ damn2

Get these books NOW while they are still available.

Pulse Power Formulary - Richard J. Adler
http://www.isi.edu/~vernier/pp_formulary.pdf

Introduction to high power pulse technology - S. T. Pai, Qi Zhang
Photocopy PDF ( This is also available on Google books to preview )
http://rapidshare.com/files/43877945/ITHPPT.rar.html
http://rapidshare.com/files/43784543/ITHPPT.pdf

High-speed signal propagation - Howard W. Johnson, Martin Graham
CHM format - from any of these ( also available on Google books to preview )
http://rapidshare.com/files/100072803/High.-.Speed.Signal.Pr...
http://rapidshare.com/files/14647580/High-Speed.Signal.Propa...
http://rapidshare.com/files/9411784/013084408X_chm.rar.html
http://uploading.com/files/OZXMD2F4/SignPropag.rar.html
See the following , it refers mostly to circuit boards but the same principals apply.
Chap 1 Fundamentals
- 1.3 - Rules of scaling
- 1.4 - Concept of resonance
Chap 2 Transmission Line Parameters
- 2.3 - Ideal Transmission line
- 2.6 - Skin Effect
- 2.7 - Skin Effect Inductance
Chap 3 Performance Regions
- 3.4 - Lumped Element Region
- 3.5 - R C Region


The most compact form of a capacitor is a roll of plastic with both surfaces metalized
leaving one border on both sides on opposite edges without metal surfacing. See attached.
Two lengths of the ribbon is spooled together with each folded back over the other. The
ends are dipped into a silvering solution to provide a base for a light electroplating of metal.
Finally an exact sized end plate of tinned copper is heated only just enough to melt the solder
surface onto which the plated end of the capacitor is pressed joining to the solder surface.
Each end is now a terminal , one end can be connected by a copper tube down the center
of the core tube to a coaxial connector situated in the center of the opposite end.

The metalized roll as described may be improvised from more readily availble plastics which
are metalized only on one side but without the border. Two are placed with the metalized
surfaces together , and two of these sandwiches are then rolled togther slightly offset to
make up for the missing border. The cylinder is now wrapped in a laminate for protection
leaving a shallow brim at the ends to apply clear polyurethane varnish. It is subjected
to vacuum to draw out trapped air to seep the varnish into the crevices. After the ends
are dry they must be trimmed to expose the metalic edging. The rest of the proceedure
remains the same.

Metallized Polyester Film is the material of choice having a dielectric strength of 7000 volts
per mil ( thousanth of an inch thickness ) or 25 microns. A capacitor of 25 centimeters in
diameter by 50 centimeters long will fit into an athletic tote/duffle bag. When charged from
12 to 14 thousand volts ( two ply mil film ) it should store 10000 Joules or more. Here Is a
sampling of sources which may serve your requirments.

Metallized Polyester Film
http://paperandfilm.com/metallizedfilmmetallizedfilms.aspx
http://paperandfilm.com/polyesterfilm.aspx
http://www.grafixplastics.com/mylar_types.asp
Electrical properties
http://www.grafixplastics.com/mylar_prop.asp
http://www.petfilm.com/specifications.html
Sizes
http://www.grafixplastics.com/mat_thick.asp
http://www.petfilm.com/tools.html
Custom rolling
http://www.grafixplastics.com/laminating.asp


Dielectric strength , measured in volts per unit thickness , is the maximum voltage that an
insulator can withstand without breakdown. It largely determines the energy density of a
capacitor , since energy density is proportional to the square of the dielectric strength.
Doubling the voltage for the same capacitance will reduce capacitor volume to 1/4 whiile
retaining the same energy.
The dielectric constant k is the measure of the permittivity ε of an insulating material.
The dielectric constant increases capacitance by the factor , k , times.
http://www.clippercontrols.com/info/dielectric_constants.html
If high energy density is required, one should use insulation having a large dielectric constant
as the capacitance is directly proportional to , ε. High energy density capacitors such as
aluminum electrolytics discharge slow. If a high rate of discharge is desired, then use
insulation of small dielectric constant as the electromagnetic wave speed ( velocity factor )
is inversely proportional to the square root of , ε , 1/√ε , also given as , k , 1/√k.

The question of how to model the circuit depends on the time frame of discharge.
Essential preconditions are a current rise time of a billion amps per second. After
a peak of 15000 or better the ideal waveform should approximate a squarewave.
- See attached copied from Introduction to high power pulse technology

In practice it is nearly impossible to discharge any paper or plastic capacitor in less than 100
nanoseconds. The pulse width can be narrowed by a delay line. Pulse width can be set by
the length of the transmission line relative to the capacitor's discharge time and the value
of permittivity ε of its coaxial insulator the dielectric constant ' k '.
A higher dielectric constant in a transmission line increases the line capacitance lowering
its impedance which slows the speed of transmission increasing the delay and compressing
the width of the pulse. A given dielectric constant ' k ' has the effect of reducing transmission
line impedance by the factor , 1/√k times , and increasing the transmission line delay by the
factor , √k times. http://www.radio-electronics.com/info/antennas/coax/coax_velocity_f...

For example a 100 nanosecond discharge fills 30 meters of common polyethylene coaxial cable ,
dielectric constant ε being ~ 2.2.
.0000001 sec X 300000000 meters/sec ( speed of light ) = 30 meters
( 1 / √ 2.2 ) = .67 , times 30 meters = 20.1 meters

Glycerine with an ε of 44 to 68 , will reduce the length 6.6 to 8.3 times , down to
4.5 to 3.6 metes

From this it is seen that optimally a short pulse generating system should be comprised of a
high voltage capacitor with a low dielectric constant discharged into a transmission line of
high dielectric constant.

See - 2.3 - Ideal Transmission line , in
High-speed signal propagation
http://www.allaboutcircuits.com/vol_2/chpt_14/3.html

High constant dielectrics such as glycerine , being fluid require custom tube assemblies made to
provide the required characteristic impedance which is determined by the geometry.
See book page 51 , pdf page 31 of
Introduction to high power pulse technology

.



[Edited on 9-8-2009 by franklyn]

Quote: Originally posted by 12AX7

One example: Electromagnetic shockwaves are easy to create in a nonlinear medium, and are an excellent way to generate extremely sharp pulses (picoseconds) -- not entirely a discontinuity, there isn't infinite bandwidth for that, but still, orders of magnitude sharper than the input. Not that this specifically applies to the immediate case.

Quote: Originally posted by franklyn

" non-linear " , I'll say , if you subject piezo ceramics to a several hundred Joule discharge , you will successfully explode the ceramic !

Quote: Originally posted by 12AX7

The shock line has to store as much energy as you put into it, so it would be rather useless to take a lazy milisecond pulse and sharpen it up. Heck, you can short one end of the line in nanoseconds quite easily, just use its energy directly. The purpose of shock lines is to sharpen fast pulses to insanely fast pulses. We're talking pulses much faster than needed here.

Quote: Originally posted by 12AX7

The mathematics of pulse sharpening say, very roughly, you need to have the entire input (rising edge) inside the line before it can do anything. If the edge is slower than the line's electrical length, it simply won't do anything, it will act like a boring wire. The point is, you need to cram the supply's energy into the line, and it has to hold that energy and do whatever to it (meanwhile, no energy is going in or out), then release the energy after it's done whatever it does.

Quote: Originally posted by watson.fawkes

Now don't go all action-at-a-distance on us. I appreciate the desire for a summary description, bu energy storage is a little misleading, although not totally inaccurate. There's energy in the electric fields of the pulse, to be sure, and all that energy might be contained in your line at one time, but the actual mechanism of sharpening doesn't require the whole pulse to be in the line all at one time.

Quote: Originally posted by 12AX7

Neeto. I'd use a small one for a sampling oscilloscope. [...] I suppose if you drive it with a cheap 10ns source (bus driver logic chips?) you can use a much shorter line which would be acceptable (an acceptable delay is under 50ns, your average analog scope has about that much delay in its amplifiers).

Quote: Originally posted by 12AX7

you must have a delay line between input and sampling to compensate

Quote: Originally posted by 12AX7

Hmm, an electric shock line's impedance is reduced, but a magnetic shock line's impedance is increased. If you build a 50 ohm coax line and load it with ferrite, you might end up with 500 ohms instead, no? Either case is difficult to match with regular 50 ohm coax. 500 ohms at least is easier to match with 300 or 600 ohm twin lead; a low impedance like 5 ohms would need a transformer to be at all useful.

High Voltage Engineering
http://ifile.it/96lravq
A very nice book short and to the point. This is an introductory text intended for
utility power engineers , so examples refer to characteristically high line voltages.
See the pictures of test equipment just before Chapter 3 which concisely deals
with pulses. Was I lying when I said , when you use Hi Voltage everything is HUGE.
One could generate equivalent power at 1/1000 the voltage and reduce the size of
equipment to 1/10 th ( cube root of 1000 , in other words increasing the voltage
by 1000 increases equipment size by 10 times at least ) High voltage is a requirement
only for - long distance - power transmission , or in this case , for test purposes.
Below is attached some excerpts from the pdf pages 93 & 94 which succintly states
some of what I have been relating here ad nauseam.
________________________________________________________________

Also below is attached a chart which compares the thermal enthalpy of metal wires
of the same size ( I don't remember the mil gauge ). It is evident why gold is prefered
since copper requires 3 times the energy to explode , and aluminum 5 times as much !
From this reference I already gave before _
EBW1 - a computer code for the prediction of the behavior of electrical circuits containing exploding wire elements
http://www.osti.gov/energycitations/servlets/purl/4229184-1IbmTb

________________________________________________________________

I just now noticed I had posted the URL's with http;// shown twice , so they are
correctly shown here now _

Scaling Underwater Exploding Wires
http://handle.dtic.mil/100.2/AD633115 , This redirects to the next link below
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD633115&Location=U2&am...

Formation & Evolution of Plasmas from Single Exploding Wires
http://www.prod.sandia.gov/cgi-bin/techlib/access-control.pl/2002/0...

This one is just ridiculus _
Exploding Wire Initiation
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19690013624_1969013624.pdf
Read last paragraph of ' General system description ' page 2 , note the time scale for discharge.

Oscillographic & Schlieren-streak Photographic Investigations of an Exploding Wire Discharge
http://www.physics.re.kr/resource/wop.pdf/J01/1984/017/R02/J0119840...

Hello Folks,

Thought I'd kick this old chestnut around again.

<b>As stated in another thread, I hereby detract anything I said about needing low inductance capacitors for the application of exploding bridgewire detonators</b>

The system is (usually) dominated by cable inductance. Use a good high Voltage to get around any inductance problems.

If Packman can do it, so can Dann2

Dann2

A collection of do it yourself electrical improvisations by Darwin award contestants.

A collection of do it yourself electrical improvisations by Darwin award contestants.

A collection of do it yourself electrical improvisations by Darwin award contestants.









[Edited on 17-7-2011 by franklyn]

" Don't know how fast the rising edge is."

Assuming average power supplies energy in excess for the mass of wire to be vaporized ,
as you note , the rise time of a discharge is what determines if it's capable of exploding a wire.
On the order of a billion amps per second , a million amps per millisecond , 1000 amps per
microsecond , with reliability , although success is achievable with a tenth of this value.

" With exploding bridge foil detonators. How does the foil 'know' what direction to fly in ? "

In the simple case it works just as the arc of Jacob's ladder here below




It's basically a miniature railgun so it will behave as this diagrams shows.



In large scale proportionally energized , the effect is just as dramatic.
www.youtube.com/watch?v=C6cV10QEGGk
( again in the simple case , this need not be true in situations where the conductors fold
back parallel to those holding the bridge , the position of the bridge in a given geometry
will determine the direction. This is not easily calculated and is definitively determined
empirically. There is much controversy about what is the applicable theory. )
http://pre.aps.org/abstract/PRE/v58/i2/p2505_1
http://pre.aps.org/abstract/PRE/v62/i5/p7544_1
http://pre.aps.org/abstract/PRE/v62/i5/p7545_1
http://pre.aps.org/abstract/PRE/v63/i5/e058601
http://pre.aps.org/abstract/PRE/v63/i5/e058602


That is the patent belatedly issued to Lawrence H. Johnston for his development
of the exploding bridgewire system that saw first use in implosion atomic bombs.
http://bit.ly/V0Ssck

.