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Lambda
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[*] posted on 1-3-2010 at 18:06


Quote: Originally posted by quicksilver  

... I did finally find a scrapyard with electronics and was overjoyed to find that I now can buy some things without working with eBay. And you all are absolutely correct as the above ss relays did sell fo about $9USA. The best thing is to go when the proprietor is at lunch as I got another powerfully switchable (this time a company called QSI that was bought out by Lamda) that pumped 150A. ...


@quicksilver,

I am pleased to read about you successes at the Scrapyard ! ;)

Working with eBay can be a Pain in the Rear, for not only are You dependent on the Reliability of the Dealer, but the Guys working for the Postal Services in My Country Holland, Steal like Raves !! And the Postal Services refuse to refund Stolen Goods, for they don't employ Thieves. I have lost a substantial $ and € amount of Goods in this way :mad:

And when dealing with the Scrapyard, by leaving the Proprietor out of the Equation, indeed can lead to a substantial reduction in Price. A Crate of Beer also works pretty well too :D

Taking a Beautiful Girlfriend along will also Impress them ! :D



A LAMBDA Power Supply is indeed a Top Notch Modern Marvel, ... how could anyone expect anything less ? And where have I heard that Wonderful Name before ? :D

More Info on Power Supplies and Triacs:

DC Power Supply Handbook

Introduction:

This handbook is designed to aid that understanding by providing complete information on the operation, performance, and connection of regulated power supplies. The handbook is divided into six main sections: Definitions, Principles of Operation, AC and Load Connections, Remote Programming, Output Voltage and Current Ratings, and Performance Measurements. Each section contains answers to many of the questions commonly asked by users, like:

- What is meant by auto-parallel operation?
- What are the advantages and disadvantages of switching regulated supplies?
- When should remote sensing at the load be used?
- How can ground loops in multiple loads be avoided?
- What factors affect programming speed?
- What are the techniques for measuring power supply performance?

In summary, this is a book written not for the theorist, but for the user attempting to solve both traditional and unusual application problems with regulated power supplies.

DC Power Supply Handbook (Agilent Technologies AN 90B - 1978, Rev. 2000) 126s.pdf
Attachment: DC Power Supply Handbook (Agilent Technologies AN 90B - 1978, Rev. 2000) 126s.pdf (1.1MB)
This file has been downloaded 461 times

Triac Control by Pulse Transformer

Introduction:

Among the many ways to drive a triac the pulse transformer is one of the easiest. By applying some simple rules it can be used to design an efficient triac triggering circuit without reduction of the commutation capability of the triac.

Why use a Pulse Transformer?

The use of pulse transformers in triac triggering circuits offers many advantages:

- Galvanic insulation between the power and gate drive circuit (a few kV).
- Gate drive circuit with a few components.
- Choice of the gate current polarity (triggering in the 2nd and 3rd quadrants for SNUBBERLESS triacs).
- Optimization of gate signal (single pulse or train of pulses).
- Possibility to drive several triacs with only one drive circuit

Triac Control by Pulse Transformer (STMicroelectronics AN436 - Rev.D2A-3575 - April 2004) 9s.pdf
Attachment: Triac Control by Pulse Transformer (STMicroelectronics AN436 - Rev.D2A-3575 - April 2004) 9s.pdf (66kB)
This file has been downloaded 362 times

Thyristor Theory and Design Considerations Handbook

Thyristor Theory and Design Considerations Handbook (ON Semiconductor - HBD855-D - Rev.1 - November 2006) 240s.pdf

iFile.it Download Link (2.48 MB):
http://ifile.it/zmie1la

No Password Required !

Pink Floyd - Money ("Pulse" Tour):
http://www.youtube.com/watch?v=6RqwLWR42nE&feature=relat...

Enjoy !

Lambda
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quicksilver
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[*] posted on 2-3-2010 at 10:23


Thanks for posting those!

The only place I found pulse transformers that were sold a a decent price was:

HTTP://amazing1.com

I DID find a Neon sign shop that was going out of business awhile back when I was making Tesla coils and got about 300lbs of HV transformers. Here we have a "club" of people that experiment with high voltage stuff but it's in the city and I have to drive about an hour to get there. but many of these guys have their doctorate in electronic engineering and have made stuff I can only dream of putting together.

I also trip into this forum, which has a wealth of info.

http://4hv.org/news.php

[Edited on 2-3-2010 by quicksilver]
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densest
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[*] posted on 2-3-2010 at 15:37


The amazing1 transformers are not what you want. You want "gate drive" or "SCR/thyristor trigger" transformers with a turns ratio of 1:1. "Photoflash" trigger transformers have a high turns ratio and deliver low current at very high voltage.

This is one case where it is usually cheaper, easier, and safer to get new parts from a distributor. You can get guaranteed 1500VRMS isolation for $4 or less and guaranteed characteristics.
For large, heavy, relatively low tech items like big iron transformers surplus is definitely the way to go, but this isn't the part to go "unknown specs" on. If you don't get it right you will get random flickery outputs and/or shorted driver circuitry, and for these pulse transformers new parts are cheaper than any surplus supplier I've found!

The biggest problem with buying these from anyone is that they're rarely classified correctly in online shopping sites. You almost have to start at a manufacturer (google gate OR scr OR thyristor transformers) and find their distributors.

One part that looks good is Pulse Engineering P0584NL. It is $4 each from www.mouser.com. Murata has a line, etc. Newark/Farnell also stocks some pulse/gate drive transformers but their search engine is pretty useless. If anyone wants some help picking the right transformer send a PM.

I know people have been trashing Mouser as a supplier. For small items like resistors, capacitors, transistors, etc. they are often the cheapest distributor - I've bought 100s of parts there after comparison shopping. They will ship any way you choose and are quick - usually 1 day from order to shipping. They also gave me a credit account :P

You can wind your own if you don't care about safety or you're willing to put 2 layers of transformer insulating tape and 10mm spacings between wires, etc... a small toroid (1cm) and 2 x 10 turns of #30 wire should do it. Don't use RFI/interference suppressing material because that would kill the pulse! There's an article on how to design one http://powerelectronics.com/passive_components_packaging_int... for the masochistic.

For a 25A SCR a pulse 3 microseconds long at 5V should trigger it reliably as long as the SCR is above 0C. It might take 4-6us if it's -40C. A huge (300A) SCR will take 7V for 30microseconds.

Using an excessively long pulse or high drive voltage will not help. The transformer will "saturate" i.e. cannot hold any more energy and suddenly look like a short circuit to the driving electronics and its output will drop to zero. Pulse transformers are rated in "volt-seconds" or "volt-microseconds": the voltage applied times the length of the pulse. Small transformers cost about $0.10 per volt-microsecond, so a $3 or $4 unit should be plenty if the drive circuit provides a short (2-4 microsecond) , high current (100-200mA) pulse at 5V.


[Edited on 2-3-2010 by densest]
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quicksilver
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[*] posted on 2-3-2010 at 15:57


NO, I know what you're saying. Mouser IS fine for some stuff. I just wouldn't buy their variacs :-)

Thanks for the tip!
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watson.fawkes
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[*] posted on 2-3-2010 at 19:37


Quote: Originally posted by densest  
You can wind your own if you don't care about safety or you're willing to put 2 layers of transformer insulating tape and 10mm spacings between wires, etc... a small toroid (1cm) and 2 x 10 turns of #30 wire should do it. Don't use RFI/interference suppressing material because that would kill the pulse! There's an article on how to design one http://powerelectronics.com/passive_components_packaging_int... for the masochistic.
Masochistic? That article's well written. The comment on bifilar/trifilar winding is particularly useful, as it would tend to lower the maximum fields in the core somewhat.

I'm confused about what you said, though. How do you get 10mm spacing on a 10mm (1cm) toroid? I suspect typo. Can't you get adequate isolation between primary and secondary with a high-quality insulation on the wires? If you need 10 kV isolation, I suppose it gets easier to use an air gap, but where's the trade-off point?
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densest
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[*] posted on 2-3-2010 at 23:11


@watson.fawkes - yes, I confused "safety" with "basic" insulation requirements: I think 1.6mm is enough for 1500VRMS - reasonably safe if the triac/SCRs are directly connected to the mains.

Bifilar/trifilar windings are really useful in many cases. If you want to isolate control circuits from nasty mains voltages or switching spikes, the increased interwinding capacitance has to be taken into consideration. Enough could leak backwards to upset CMOS logic or microcontrollers, etc. You always have to trade isolation for parasitic capacitance and efficiency :(

Personal safety using the equipment can usually be ensured with a GFCI in the mains.

Keeping the logic happy is important. I learned many years ago that while most ICs have good protection on their inputs, they are quite vulnerable to high energy transients on their outputs which far too often exit through the ICs inputs to the previous stages. :mad: So I worry a lot about the design where the 3V/5V logic meets the power line.:o

I have a piece of a power line inverter (probably from something like a 50-100 KV DC system) comprised of stacked high voltage SCRs. The trigger transformer is unique. Each SCR has a secondary wound on some toroids spaced for high voltage. The primary is a straight wire in a thick insulating tube passed through the center of the toroids. Lousy coupling, but at 20KV/mm, the system is set up for 100KV. I use the assembly as a hat rack. :cool:

PICT1984sm.JPE - 119kB

PICT1983sm.JPE - 174kB

PICT1982sm.JPE - 82kB
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[*] posted on 2-3-2010 at 23:56


Cute.

SCRs are an awful lot harder to handle than MOSFETs (or IGBTs). Lossy and slow, you can get a lot more power and efficiency from FETs, with far smaller transformers because the operating frequency is higher. The same voltage and fault conditions exist (less, actually, since MOSFETs don't stay on once you trigger them).

Dollars per weber is a curious measure for a pulse transformer. I have some which should be very expensive indeed, then; 2000 turns will easily take several webers (not uWb!). Seems to me, a more useful measure is wattage, since the current that a given winding can be manufactured for depends on the available winding window, which is a matter of core size.

Tim




Seven Transistor Labs LLC http://seventransistorlabs.com/
Electronic Design, from Concept to Layout.
Need engineering assistance? Drop me a message!
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densest
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[*] posted on 3-3-2010 at 05:11


@12AX7 - quite true, SCRs and triacs don't want to move in a hurry, have relatively high "on" voltage, and require substantial trigger power. They're still made in huge quantities because they're cheap, cheap, cheap, rugged, and are fast enough to use in dimmers, small variable speed motors, etc. For those applications, no transformers are used at all - all isolation is done with insulation or open space and the drive circuits are very very simple. Did I mention cheap? and easy to make for relatively high voltage operation and surge tolerant. All good for consumer items not needing to be superbly efficient. Cheap. And easily made on old semiconductor manufacturing equipment in a basement somewhere.

I was using $/wb because (simplified probably too far) a trigger/gate transformer is normally used to drive a moderately high impedance (mostly capacitive) with a defined waveform and power isn't a limiting factor. Yes, driving a FET/IGBT can require multi-ampere spikes at turn-on and turn-off, but in between the current approaches zero. So the required performance is often limited by how long the drive can be applied before saturation and the charge/discharge current, not by power transferred. And most manufacturers specify volt-microseconds, inductance, winding resistance, and turns ratio as the primary characteristics of the devices. A matter of convenience, really.
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[*] posted on 15-3-2010 at 16:40


I have been have OUTSTANDING luck with Power Supplies, High Voltage goodies and bits at this site (which I highly recommend):

http://www.surplussales.com/index.html

Best thing is to talk w/ them on the phone. Their "hook" is free shipping after $100 or equivalent in Euros. They have a GREAT deal of Lamda stuff, - they seem like they enjoy "dealing"; so many prices may come down a bit.
Los Alamos stuff, & military gear. Some of the high amperage SWITCHING supplies are at $30-40 for a 5Vdc / 30A and great savings on HIGH VOLTAGE (hard to find) components.... They also have damn good Rack mounted supplies. Some are tested - others are "as is" but all are priced accordingly. :P

PS - an "as is" was simply a complex multi-switching supply (5vDC @ 150a) that had no manual and in a few hours I learned to set it up (the trim pots are wax sealed from the lab to match the material printed on the component.
That one was perfect for BIG tanks. Today I cleaned a 5 gal bucket cell which netted me 6 lbs dry KCLO3 with graphite rods and 10days but used perhaps 60a. If I wanted to deal with the graphite - I think that supply could handle a horse water feeder at 200 gal or a serious high volume plating.







[Edited on 16-3-2010 by quicksilver]
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Lambda
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[*] posted on 15-3-2010 at 18:04


Quote: Originally posted by quicksilver  

... PS - an "as is" was simply a complex multi-switching supply (5vDC @ 150a) that had no manual and in a few hours I learned to set it up (the trim pots are wax sealed from the lab to match the material printed on the component. ...


@quicksilver,

You may be referring to this Power Supply:

Lambda Power Supply - Model (PS) LGS-EEA-5-OVR





Lambda regulated power supply. Over voltage protection. Original price = $1,176.00.

• Input: 105 - 132 vac @ 47 - 440 Hz
• Output: 5v @ 150a @ 40ºC reg. 0.1%, 96a @ 71ºC
• Dimensions: 4-15/16" x 7-1/2" x 16-1/2"
$795 each

But, ... have You seen this One on the same Web Page which can Pump a Massive 300 Amps at 5 Volts !! :o It does have a different input Voltage of 230 VAC, instead of 105 - 132 VAC mentioned on the previous Model.
http://www.surplussales.com/PowerSupplies/PowerS-3.html

Jeta Power Supply - Model (PS) CP137







Jeta Model CP137 power supply. No manual, no cords. Not rack mountable. Mfg. P/N: 725-3308-1.

• Input: 230 vac
• Outputs: 1850 watts, V1: 5v @ 300 amps, V2: 12v @ 20 amps V3: 5v @ 10 amps, V4: 12v @ 5 amps
• Dimensions: 12" x 18-1/2" x 5"H
$125 each

Fine Young Cannibals - The Flame (VHS Remaster):
http://www.youtube.com/watch?v=GHYdaorAKY4

Lambda
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quicksilver
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[*] posted on 16-3-2010 at 08:51


I don't have a phone camera with me or I'd post it. There's a "QSI" (sold to Lamda) w/ fans that 150a @ $40 It is a "as is". no manual, not material at all. It was strictly a gamble. But I'LL do that;. I really know little about electronics but I worked as an electrician through the construction industry and have a very effective way of problem solving.
I got it going and SLOWLY figured out all the idiosyncrasies. $40 for a 150amp switching supply that is MADE for 24/7 use! I was stoked. They also have quite a few excellent 5Vdc 15a NEW supplies that simply need an enclosure, some are 5v and much higher. An enclosure is not only easy but you can put more than one fan to create a "flow-through", that's very effective!


On another (somewhat off topic) subject I have a warning for some of you who use Gouging Rods for anodes/cathodes. IF you have prepared your rods carefully with dilute acids to knock out the remains of copper and iron you may sill get a batch that is off color(beige). That material should unquestionably be re-crystallized. Unless your batch is white as snow; re-crystallize. With this you take out an insurance policy. An untreated rod will not last very long where a well treated rod may last more than 2 weeks! But introduced into the brine might be a fuel (especially if that same rod is used for a long time).
There is a possibility that some other material was left within the the chlorate (or perchlorate) crystals. this may constitute the same as material as a fuel, intimately mixed in the chlorate! Just like BP, the mix would be extremely intimate and the result could be very serious IF the material was exposed to any stimulus. Re-crystallized until you have a snow white crystal. Linseed oil, shellac, carbon, etc are all fuels! The mix would be very intimate similar to a PB mill. I strongly suggest to recrystallize, as ANY fuel with a chlorate is a serious problem. The off white color may be an indication of some type of fuel. It may also be an indication of a simple color change from filter paper or inks; but why take a chance? This issue generally takes place in a large cell but regardless, if you believe your resultant material may have something "extra" - do something about it.
If the material is off color when still wet, let it dry and see what takes place. A crystal can "throw off" a dye of sub micron carbon just as it can retain it. Take a very small sample and test. PURE chlorate with no fuel should not take fire in the same manner as one with a fuel. Friction & impact will differ also. If it acts quite sensitive - clean it further.





[Edited on 16-3-2010 by quicksilver]
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dann2
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[*] posted on 16-3-2010 at 11:13


Hello Quicksilver,

Quote: Originally posted by quicksilver  
.......... An untreated rod will not last very long where a well treated rod may last more than 2 weekks!........
[Edited on 16-3-2010 by quicksilver]


Are you using pH controll with these rods?

Dann2
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quicksilver
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[*] posted on 16-3-2010 at 12:19


I only used untreated graphite once (those were"bars" of graphite 2"x1/2"x10") and did control ph but they broke down pretty quickly. So I shut down and from then only used treated rods and with those -Yes; by that I mean I'll maintain 6.5-7 ph. I test at the beginning and at 2 day intervals. However I'm using a lot of current as compared to what I had previously used. Using the formula you described previously I was pretty low before. I don't have the numbers in front of me but I had used 3a with 2.5 L which should have been higher. I know that I'm low because with another cell with Ti/MMO mesh I would get formation within the perforation (of crystals). Kick it up a slight bit and not crystal formation occurs in the perforations.

I believe it helps the rod's longevity (stringent ph monitoring) but I'm not convinced that the rods are consistent in porosity or density. Opinion-wise I think that anytime enough current is moving through there to maintain 50+ C, the rods' going to "shed". I get enormous yields of chlorate with graphite and the cost is low but the mess and lack of snow-white crystals (even from a rolling boil to re-crystallize) makes me think that the extra work is the trade-off.
I'd be curious to try an experiment wherein a dye is placed in the tank prior to cultivation and see whether the crystal forms without it from a single recrystallization. I pulled one after 10 days and the crystals -appear- beige, but are still moist and I am going to dry these out as the water from graphite is SO stained that it may be I am looking at dyed water. However I have seen some that unquestionably had not been purified by a single recrystallization. Those that were stained within the crystal were hyper-sensitive.



edit 3/17/10
well I tried 3 re-crystallization and ALMOST got that yield water-white but it still had some beige in it. I believe that it may be from the linseed oil. I'm disappointed in it's lack of purity wherein the MMO/Ti material is about as clean as it gets from a single re-crystallization. Of course I'm going to keep it separate and do a heck of a lot more testing to determine if it's safe. However I am pretty disappointed that such a high yield may not be the ideal method. I'm going to try another but with a great deal of attention to ph AND I'm going t remove any outer layer of linseed oil even if it's not obvious (this was not obvious to a greater degree) but better safe then sorry.

[Edited on 17-3-2010 by quicksilver]
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