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Author: Subject: Electrochemical ozone generation
Natures Natrium
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[*] posted on 5-12-2006 at 09:06


Cool, I was somewhat worried I might have gotten a POS, still might, wont know until I fire it up.

Heh, I uh, still havent gotten around to getting a multimeter. So, are you thinking the main lead off the secondary is the thin red wire, or that plug that comes off the side? I am unsure, as the red wire seems to come from the center of the secondary, but looks way too thin to support any kind of high voltage. The plug on the other hand looks stout enough and the metal connector inside is actually deep enough to be inside the resin block, but it appears to be coming off the bottom of the secondary. Any thoughts?

Here, a pic of the other side should help:



-NN




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[*] posted on 7-12-2006 at 12:28


Well, I got something at least. After messing with the PC power supply for a bit (and figuring out how to trigger it to "ON" status), I tried my circuit out. At first I got absolutely nothing, and then I realized I had wound my feedback coil exactly opposite of my primary. Took it off, rewound it. Now I am getting juice through the system, but it appears to be pretty damn low power.

The NST would start an arc between two pieces of aluminum foil at about a cm, which would then grow to a white arc of ionized air at about 3cm before it would pop out. With this setup I am barely getting 5mm of arc. The good news is it does sound like a MUCH higher frequency than the NST, but I have to figure out a way to get more power out of it than this. Hooked to my alumina tube setup, I get no observable effect.

Also, I was very confused about the ground lead, the one than comes off the other side of the HV arc. Does it ground to someplace on the secondary, or does it ground to the ferrite core itself? Powerlabs doesnt makes this specifically clear, and I am as of yet too ignorant to deduce the correct action.

EDIT: Alright, realized I was one wrap short of the powerlabs design on my primary, did that, it did help some. I still cant really get these coils really tightly wound and close to each other, that solid core stuff just has too much memory.

Also, did some math:
NST: 30mA @ 10kV = 300W, it uses 316W @110V to produce this.

ATX PS: 16A @ 12V = 192W, so @10kV, the theoretical A= 19.2mA, or not suprisingly 2/3 the power.

However, I realized something else, that the 16A rating on the PS apparently only is valid for the +12V (yellow wires). The only -12V line is a single blue wire, and its maxmum rating is just .8A, or 9.6W, ie 3% the power of the NST.

The bottom line is that despite the convience of it (I even put a CPU fan on that CPU sink, since the transistor was getting warm, and it was convient to tie into the 12V lines with it), I dont think this PS is going to work.

What I really need is about 25A@-12VDC. (Equals 300W.) Does anybody else think that will make my transistor a heating element for a very short period of time?

-NN

[Edited on 7-12-2006 by Natures Natrium]




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[*] posted on 7-12-2006 at 16:33


Yeah that's a good point at which to use MOSFETs and a good squarewave circuit to drive them.

Tim




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[*] posted on 7-12-2006 at 17:05


Quote:
Originally posted by 12AX7
Yeah that's a good point at which to use MOSFETs and a good squarewave circuit to drive them.

Tim


*Sigh* Know where I can buy one? Or a relatively simple way to frequency double 10.5kV AC a couple of times?

I think I will go back to working on the actual ozone tube design, as I am flat out of "play time" money for at least a month.

-NN




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[*] posted on 7-12-2006 at 17:39


No! You don't need a more powerful 12V power supply, and you certainly dont needs Mosfets!

The flyback driver draws about 3-5 Ampere of current from a 12V supply when under full load. There is no way you can make it more powerful using 12V.

What you need is a 24V power supply! 10A of current output capability will be plenty there.

It is the same with my flyback driver: with 12V I get only thin 5mm arcs, but with 24V I get at least 1cm and they are much hotter.




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[*] posted on 7-12-2006 at 18:58


Wow, I just typed up a whole bunch of stuff, and then lost it when I mysteriously could not connect to scimad for a bit. Hmm, reminds me of the mid-90s and the whole AOL scene.

First, thank you for setting me straight on some misconceptions, I do so ever appreciate it. :)

Second, I think borosilicate glass might be too conductive when using a system like that in the paper I uploaded. I tried wrapping the outside of a 300mm condenser with aluminum foil (a 100mm area, centered in the middle), and using the NST I found I had corona on the wire clear at the top, well away from the aluminum foil area. I question the effeciancy of a system which utilizes two salt water electrodes, both of which are in direct contact with a piece of glass that is eventually contiguous (as in the paper I uploaded). Maybe this is why Vogel was saying that borosilicate is not satisfactory for an ozone generator? Still, in that paper they reported ok results, and were using 20kV, 60Hz, @ ~500ma.

Third, I am still trying to think outside the box in terms of design, and see if I cant come up with something original, easy for the hobbyists, and relatively efficient.

-NN

PS I still wonder if that guy really had a 75kV transformer or not. :P




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[*] posted on 8-12-2006 at 07:50


Quote:
Originally posted by garage chemist
The flyback driver draws about 3-5 Ampere of current from a 12V supply when under full load. There is no way you can make it more powerful using 12V.


Nah, sure you can. Fewer primary turns (and fewer feedback turns to compensate) and more amplification (i.e. current handling) will draw more current with the basic circuit.

Up into the 10-20-50-100A range at low voltage, the 1-3V forward drop of BJTs starts looking real infuriating, so you also want to use MOSFETs, which reach very low ON values (a chunky 0.003 ohm Rds(on) MOSFET drops less than a volt at 30A) and heat less, using more of your supply voltage as well.

But yeah, really, anything with more amps than volts is impractical. You could do worse than rectify line voltage and run 160V at a couple amps instead! Heck, you could even use IGBTs for that (albeit at little advantage to more robust MOSFETs or more so BJTs). Easy enough to put on a whole bunch more turns and run that sort of voltage.

Of course, at this point you have to consider the size of your FBT. Even the biggest in use are designed for perhaps 30kV at 1-2mA, or 30-60W. More than 100W for much time will certainly burn it out, and that's if it's a bigger one.

You can quite easily step up voltage: if you have an AC source, you can use a transformer to produce higher AC, or a voltage multiplier to create DC. If you have DC already, you're SOL on that end. If you want to do this with glass insulators, you obviously need AC, anyway.

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[*] posted on 9-12-2006 at 15:52


Study study, learn learn. Could anything be better?

Well, I have been playing around with a small U-tube I have. I found a way to get a fantastic amount of corona in it, but the damn secondary ground fault on my transformer keeps tripping it off. >_<

What I did was wind 3 seperate pieces of a single strand of copper wire from my 12-gauge stranded around a length of the still insulated 12-gauge. I wound them in such a way as to form a triple helix. Then I pushed the wrap through the U tube, grabbed onto the 3 wires at the other end, and pulled the core wire out, leaving a cool looking triple helix of 3 very thin wires. Application of the NST to this setup (the U-tube dipped in a salt bath attatched to the other end of the transformer) produces a bright purple glow that fills the tube completely... for about 3-5s, max.

Midedit: Just messed with it some more, got it to work properly. The discharge must be heating up the air, as on application one end of the U-tube feels like it has a small fan behind it since it is emitting quite a lot of air.

If I get a couple more of these U-tubes and set them up in series (as regards O2 flow), I think a pretty damn efficient generator could be made. The U tubes each have two air flow nipples as well as the usual testtube-like tops, so the wires come in through teflon-coated rubber stoppers, and the hoses hook onto the air flow nipples.

So far this is looking promising; cheap, easy to build, solves cooling issues, and hopefully turns out fairly efficient. Any work on the flyback driver is halted, as I clearly need a higher voltage DC source, and I wont be able to afford one until probably after the New Year.

-NN




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[*] posted on 15-12-2006 at 16:56


I have been thinking pretty frequently lately about how to implement an efficient design, as well as spending some time just playing around to get a feel of the characteristics of high voltage discharge.

This is what I came up with (so far):



I came up with the idea of solder-filled glass tubes after I considered that silver plating the inside of one of these would make an excellent electrode. While having two layers of glass, one on each electrode does work, I notice a considerable drop in overall intensity. Rather than simply have a wire inside the glass tube, which probably wastes minute amounts of energy, I wanted to fill the tube with a conductive metal. Silver containing solder seemed like the best choice from given that low mp, good conductability, and ease of acquisition were all valid factors.

The outside being made of "hard" plumbing copper is convienent both by the fact that it is very conductive and its easy to assemble into whatever shape I need.

I cant decide whether or not to make the cooling bath brine or not. It would allow lower temperatures, but it seems to me from my observations and playing around that larger amounts of salt water tend to drain a bit of energy from the system. I wonder how much better tap water would be as an insulator as compared to brine. I know they used to make large, barrel sized resistors this way.

The bath itself would be in a styrafoam cooler, setting on top of an inverted cooler of the same type. Distance and insulator to help prevent wasted dispersion of charge.

The gap between the electrode and the copper tubing will be on the order of 1-2mm. A rather slow feed of gas will be necessary, since there wont be much volume inside the system, but this way all the O2 moving through is constantly exposed to the corona, save for the bottom "U-joint". If necessary (or helpful), I dont think it would be too much harder to set up a series of these (Im thinking 6, max). It would depend on whether or not my PS can power a larger system without overall loss on yields. Also, once I get a 24VDC source, I want a system that wont overwhelm my flyback driver.

Please, if you have any helpful ideas or comments, or can point out grievious mistakes, feel free to do so.

-NN

EDIT: Oh yea, length of glass electrodes should be ~30cm, so outer copper tubing beneath water should be ~25cm.

[Edited on 16-12-2006 by Natures Natrium]




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[*] posted on 15-12-2006 at 17:12


Sounds reasonable. Be sure those capillaries are sealed! ;)

Don't worry about resistance; connected to the copper, the HF current will travel mostly along the inside surface of the copper (most of the copper at 20kHz, but a few mils of the surface at 200kHz, say).

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[*] posted on 23-12-2006 at 17:54


Got it all built. I wanted to take a picture, but I dont have a digital cam (still). I will get pics up as soon as I can.

Pretty much everything was built to spec. I used a few tricks I had read about a long time ago regarding glass blowing, and sealing the tubes was a cinch. I wasnt aware that solder had an organic component in it, a high bp glue-like stuff which I was informed by a friend was that "flux" stuff I am always hearing about. Filling the tube was easily accomplished by feeding the silver solder (62/36/2) into the tube while keeping the glue like stuff right on the edge of boiling. A 10-gauge solid-core copper wire was bent into a C-shape, and the ends were inserted into the two seperate electrodes by heating the solder to liquid, inserting, then cooling, one at a time. I have to admit it was pretty neat to create glass covered solid metal electrodes so easily.

Unfortunately, during operation the glass covered electrodes are still getting way too hot. Too bad too, it was really cool to look into the copper tubing from a side port and see all the air inside lit up a glowing, deep purple color. The first electrode broke pretty quickly, allowing an arc to form through the crack. I figure it was because I had to force the rubber stopper on with too much force, so I made a third electrode and drilled out the stopper a bit more. However, the 3rd one broke as well, and this time the glass was a bit frosted in a circular shape where it broke, making me think it was more a product of heating than physical mishandling. I havent tried running the setup with just the remaining in-tact electrode, as I dont want to overheat and break it as well. I am currently thinking that the 300W of power that the 10.5kV NST is providing is simply overwhelming any sort of cooling that the water, or air being pulled through the system, provides.

(On a side note, when I made the third electrode I broke apart the glass on the first and recovered the solder. Feeding this into the new glass tube proved to be far more hassle than it was worth, however if anyone is wanting a smallish lead/tin rod-shaped electrode for something, this might be a good way to do it.)

When I get my 24v PS, and if my output from the flyback is in the neighborhood of 20kV @ 3mA, then the 60W total power should provide much less heat to the system, as well as providing a large increase in yield thanks to the high frequency of the AC current.

Even though any trail is a success regardless of whether or not the actual setup worked as expected, assuming that data is acquired which leads to an even more likely construct, I could not help but to feel a but bummed out when I ended up with two broken electrodes. Still, I want to continue foward until an easily achievable means of acquiring molar amounts of ozone is obtained. There is just WAY too much neat stuff that can be done with it. :-)

Finally, my necessary QUESTION for the day: Can someone explain to me why it is easy to find a 24V @ >5A PS that only has a positive terminal, but all the ones which have both positive and negative terminals at that ampreage are usually twice as expensive? At least, thats the impression I have gotten while searching ebay and online stores. Thoughts?

-NN

EDIT: Oh yea, is there a way to double voltage while halving current? Like making one of those old style transformers you see in the B&W pictures. Say, 20 wraps of 10-gauge solid core on the outside and the inside coil being 40 wraps of very thin, enamal coated magnetic wire? Does it work by powers (ie 20 wraps outside, 400 inside to get 2xV, and less than .5xA)? websites links for me to learn more? (Wikipedia has a bit, but I found more historical refs than actual useful info, which is neat but not helpful to my projects.)

[Edited on 24-12-2006 by Natures Natrium]




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[*] posted on 23-12-2006 at 21:17


The conversion for transformers is a simple ratio, though of course, this is the real world, and losses occur for various reasons. In theory (and a perfect world):

Voltage in / Voltage out = # wraps in / # wraps out
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[*] posted on 2-1-2007 at 05:23


i built and ozone generator a few years ago for deodorizing purposes..
i do not need a very strong concentration of ozone for those purposes so i went for the easy way by photocatalitic reaction:
i took a mercury light and removed the bulb carefully exposing the inside mercury bulb, then i placed it inside a box, with a big computer fan blowing tru, and build a labyrinth so that is impossible to see the lamp directly.
when turned on it created enough ozone to deodorize my garage in 20 minute..leaving for longer increases the concentration up to the point which u can't breat and your eyes water..




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[*] posted on 3-1-2007 at 11:59


simple is better.... simply by taking of the glass of a mecury bulb!? what was the wattage like 50-100..or 1000

why the heck am i fooling around with cracking pyrx glass every secound...
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[*] posted on 3-1-2007 at 14:24


exactly.
the power i used was barely 70W, and luckily i didn't buy anything more powerful..otherwise it could have been quite a bit of a problem..the important is having a nice big box (mine is approx 25liters, with insides covered with tin foil..
this way u will maximize the UV exposion of air..




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[*] posted on 3-1-2007 at 15:18


Potentially stupid question to those in the know but...
I have a vaccuum leak detector, in otherwords a small handheld tesla coil, it makes inch or so sparks to a ground. Whenever I play with it there is a noticable ozone smell, however, would this work well in the tube type of ozone generator as the power source? A couple pages back someone said the higher the voltage and frequency the better, so is this an ideal power source?




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[*] posted on 3-1-2007 at 21:42


Why yes it can. Even in a world class shitty rigged-together-in 10-min-setup!
It oranged the KI solution in about 20s
Air was drawn through with an aspirator. Just a copper tube in the centre of a leibig condenser, filled with .3ishM CaCl2, copper fibers taped on the outside.

In the background is a smaller, failed ozone tube.

I tried with tinfoil instead of the copper fibers, and it did work better, but I used the copper fibers so I could see the tube glow blue in the dark.:P

[Edited on 4-1-2007 by The_Davster]

OZONE.JPG - 50kB




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[*] posted on 4-1-2007 at 17:23


Ok, triple post, but I have a cool picture:P

All I need is some ozone proof tubing for the output, and a water pump for cooling(I hate using the tap to run cooling water), the pump I origionally bought does not have the power to pump though all those coils.
Even without cooling there is much ozone smell at the output right after turning it on.
I also plan to build a clear plastic box around it, I attempted to keep the HV isolated as best as I could(note the electrical tape:P), but more is better.

EDIT: AARG...tested it on KI solution....the first crappy generator I rigged up worked better than this. I think I have too much foil surface area.

[Edited on 5-1-2007 by The_Davster]

[Edited on 5-1-2007 by The_Davster]

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[*] posted on 19-2-2007 at 14:58


Hmm, I recently resumed expirementation on this project, but I have been having some spots of trouble.

First off, I found an 18.5v, 6.25A power supply in the form of a power brick for a laptop. Got a good deal on it too.

Then, I promptly burned through 3 2n3055 transistors in a row when attempting to use this power supply. Hmm. The third time I actually drilled two holes in the bottom of the AMD stock cpu heatsink, mounted the transistor with arctic silver, and attatched the stock fan that came with the sink. Still burned it up.

Mounted a 4th transistor (I looked around for some higher power handling alternatives that powerlabs recommended, but couldnt find any), also a 2n3055, and ran the PC PS supply, which supplied its 12V@800mA, and I was suprised to find that the aluminum block got warm and the transistor was almost too hot to touch after just a few minutes of drawing (very small) arcs.

I am really at a loss, as I feel that something is causing the transistor to heat up much too quickly, but an examination of this simple circuit compared to the powerlabs tutorial showed that, as near as I can tell, it is set up exactly as he had his.

If anyone has a clue or idea, please feel free to share.

Also, I had an idea, while I was examining how speaker amps work, and suddenly realized its not so different from my setup, and if I understand how speakers work correctly, is capable of generating high frequency current (15-20kHz) pretty easily. Some sound gurus on another forum (which I forgot to bookmark, damnit) were suggesting that a 200W amplifier often put out (with certain sounds) as much as 24V, which simple math would indicate was about 8A (unless the 200 is an indication of the power used, not power outputted, which I dont think it is). Could probably get away with a 100-150W amp at max volume, playing a CD that is a 70-minute track of a continous 20kHz pitch. This would be the input into the flyback.

I thought this was a rather novel idea, which immeadiatly made me think it probably wouldnt work because there is too much I dont understand about electronics to be coming up with novel ideas.

Anyhow, what do all of you think?

-NN




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[*] posted on 19-2-2007 at 15:36


Why not just use a simple signal generator? Even a 555 with some low pass filtering and a buffering op amp will give an OK sort of sine.

The 555 might be better, if you're running the transistor as a switch or class C or D amp. The square wave out of a 555 is going to reduce the time spent between on and off states, which reduces power disappation in the switch. You'll still want snubber diodes if you're driving an inductive load.
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[*] posted on 19-2-2007 at 17:17


Self-excited is fine.

How did you wire it? I was talking to someone just last week who connected the base directly to a tap on the winding! How silly!

The 3055 is such a POS transistor. Tough as nails and an old standby, for sure. Above say, 10kHz, it's worthwhile to invest in some better transistors. Give Digikey and Onsemi a browse (Onsemi has samples, although shipping is not free).

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[*] posted on 19-2-2007 at 18:22


Quote:
Originally posted by 12AX7
How did you wire it? I was talking to someone just last week who connected the base directly to a tap on the winding! How silly!


Hmm, if you are refering to the secondary, it is encased in a polymer of some sort, and I have read that it is very difficult to make the secondary winding on a flyback since it uses 40-gauge wire and many thousands of wraps. I have not altered it at all.

By base do you mean ground? I am using the black wire as my ground, since it produced the largest arcs when using the PC PS.

Quote:
Originally posted by 12AX7
The 3055 is such a POS transistor. Tough as nails and an old standby, for sure. Above say, 10kHz, it's worthwhile to invest in some better transistors. Give Digikey and Onsemi a browse (Onsemi has samples, although shipping is not free).


Hmm, if it is tough as nails, then why have I burnt through 3 of them? Given what the powerlabs dude claimed he did with his, I really dont understand why they keep frying out on me. Isnt the 3055 rated at ~70v and several hundred watts?

Quote:
Originally posted by not_important
Why not just use a simple signal generator? Even a 555 with some low pass filtering and a buffering op amp will give an OK sort of sine.


Well, to be honest, because I dont really know what any of that is. A 555 is a mosfet transistor, yes? How do I do low pass filtering and what is a buffering op amp? Would trying to build a circuit like this be cheaper and easier than rewiring a cheap stereo, and attempting what I mentioned earlier?

Quote:
Originally posted by not_important
The 555 might be better, if you're running the transistor as a switch or class C or D amp. The square wave out of a 555 is going to reduce the time spent between on and off states, which reduces power disappation in the switch. You'll still want snubber diodes if you're driving an inductive load.


Alright, I am going to do some more research to educate myself on all these terms and meanings, as I really have no idea what you are talking about.

Thanks for the replies guys, I do so appreciate any and all help I can get. If there is a simpler and more dependable way to create a ~20kHz freqeuncy than trying to depend on the feedback winding to trigger the transistor off and on, I would definetly be willing to take that route.

-NN




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[*] posted on 19-2-2007 at 18:33


Try

http://www.uoguelph.ca/~antoon/gadgets/555/555.html

http://en.wikipedia.org/wiki/555_timer_IC

for starts. A cheap way to get an oscillator (astable mode) when you don't need really tight control of the frequency. It's output is husky enough that it often can directly drive power transistors.
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[*] posted on 19-2-2007 at 19:10


Hmm, ok, if I am understanding this correctly, wiring up a 555 to the flyback circuit in place of the feedback winding would be a way to control the transistor state. But, it looks as thought the 555 also needs a control for starting/stopping its timer (applying current to pin 2 (TR)), which means I still need something to create a high frequency. It also seems to me that whatever I use to create the high frequency pulses might as well be directed at the transistor in place in my circuit (unless those things dont generate enough power to trigger a transistor state?). It all seems rather redundant, since that transitor is the primary problem I have been having. (Hmm, afterthought, unless the voltage applied to pin 2 can be left on continous, so that everytime the 555 triggers off it immeadiate starts to cycle again? Then the frequency would be soley determined by the capacitor/resistor combination. Hmm.)

I still am wondering, would using the leads normally going to a speaker work to drive the flyback primary directly?

I looked through digikeys catalogues, but 99% of it was greek to me. I did notice that some oscillators had frequencies in the 100's of MHz range, too bad the secondary on the flyback probably wouldnt have time to collapse before the next field pulse from the primary formed. (Yes?)

This 555 thing looks very interesting, but I think I need something simpler and more direct. Actually, thinking about it, triggering a transistor through the feedback winding probably IS the simplist way to do it, too bad its not working out for me.

Still, in my pursuit to create ozone, I have realized how cassette tapes, power transformers, car detectors (at stoplights), and a whole bunch of other stuff works. Those sudden revelations are always fun. ;)

As far as replacing the transitor in the existing circuit goes, I could definetly use some suggestions.

Again, many thanks, if I can get a good source of power to my ozone design, I am fairly confident it is going to work quite well. :D

-NN

[Edited on 20-2-2007 by Natures Natrium]




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[*] posted on 19-2-2007 at 19:33


Running a 555 in astable mode is a pretty simple way to get an oscillator. Using a varible resistor in the frequency control part of it would allow for fine tuning of the frequency; this can be done with a pot that's 10 or 20 percent of a the needed value and a fixed resistor for the rest.

The 555's output would drive a power transistor, you're switching a fair amount of current with it. Likely you will need diodes to shunt the reverse inductive kick of the flyback. If you drive the flyback at frequencies too far from it's designed one, too much current can be pulled from the driver transistor, overheating it, so you'll need to run near normal flyback frequency; trying to use the feedback winding is more direct, but a bad design can result in either or both running at the wrong frequency, or not driving the transistor hard enough. Whe the transistor is driven properly, it spends much of the time in the full conduction state of full off, when the drive is too low it spends more time in the partially on state, where it works like a resistor and generates more heat.
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