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CCFL mini tesla coil

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Michalis.Biochem

Thu Oct 28 2010, 10:52AM

Registered Member #3340 Joined: Wed Oct 20 2010, 07:28PM
Location:
Posts: 69

So now i got another idea, how viable would it be to build a CCFL mini tesla coil?
I mean, an CCFL inverter can generate HV that would be enough for a very small tesla coil to operate. This is just an idea, so i would like to here your opinions

dingo27

Thu Oct 28 2010, 12:35PM

Registered Member #890 Joined: Tue Jul 10 2007, 10:06PM
Location: Slovakia
Posts: 180

I think a proper circuit can always be better than using ccfl - is that camera capacitor flash light?

Its too weak to make any

work

//edit: oh, nevermind.

quicksilver

Thu Oct 28 2010, 04:33PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

I have recently experimented with some "mini's" (SGTC) & to the best of my knowledge the lowest level of current is somewhere at the 2-3 ma mark. I do not know if by extremely well constructed secondary in precise balance with the input energy it could be dropped any further. However the biggest stumbling block was the secondary construction. I was able to use 40awg wire with a 1" tube for 800turns: it had to be wound by hand it was amazingly difficult to build on a thin walled tube.

I did keep in touch with a guy who used a flyback which he said was putting out 11k @ 2ma but he said that the some of the usual calculators didn't like that low of a input. And there was a awful lot of trial and error. That's actually an understatement because it would (appear to) almost accidentally slip in and out of tune. The good news is that capacitors were not too much of a problem as the overall current was so low. CDE 940 series were just fine as they are typically lower current design than the 942 and very inexpensive.

HOWEVER a FLAT secondary DID respond to very low levels of input energy. There are some electronic engineers who may know the reason why, at a certain level, the construction becomes much more of a challenge to build a small coil, but from my experience, there is a point of very low returns.

My experimentation was with arc of approx 2cm from source however the "real-life" spark gap that was needed was unusually tiny. This in turn presented a problem in using anything but a single gap SG.

However what I was looking for was a coil that would function for more than 20-30 seconds. To that end I was forced to use a tiny NST from a bug zapper as the fly-back & driver I used (AC) produced very inconsistent out-put. It MAY also be that lower power levels low quality power transmission lines (like those in a rural area) play a significant role. Even then, tuning it was a great challenge as tiny movements of primary tap placement affected it's performance and the spark gap was frankly a hit or miss situation because movements of less than a (perhaps) a third of a mm was needed.

A friend with a great deal more experience that I had, helped me and said that there was some reason that he did not fully understand that the hollow core transformer model was not taking place below a certain level even with downsizing all components appropriately. This may be why the "pancake" design flat coil appears to be successful in utilizing very low levels of energy. .....Just my opinion but the smaller you go (past a certain level) the tougher it gets to get a coil in tune.

Adam Munich

Thu Oct 28 2010, 09:49PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

@dingo

I think he means Cold Cathode Fluorescent Lamp power supply. Typically they give 1.5kv at a few milliamps.

william L

Fri Oct 29 2010, 12:21AM

Registered Member #3093 Joined: Mon Aug 09 2010, 11:40PM
Location:
Posts: 68

So now i got another idea, how viable would it be to build a CCFL mini tesla coil?
I mean, an CCFL inverter can generate HV that would be enough for a very small tesla coil to operate. This is just an idea, so i would like to here your opinions

I have done this three times as a mater of fact. Just some things I have learned:
*ccfl drivers will die instantly if you reverse you power leads accidentally.
*they aren't designed for high current draw
*although they can't really shock you, you can get a small, but not fun burn spot from it.
I suggest getting many similar ones, and putting diodes on the output, so you can parallel them.

Adam Munich

Fri Oct 29 2010, 12:50AM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

Not all of them die instantly. In fact I have 3 of them with protection diodes --only the really cheap chinese ones omit the diode.

You're right, they can't supply much current. However I did find one that I was able to draw 1.5cm arcs from. It only supplied 3kV so there must have been quite some current there. I can't find the exact one, but here is one like it, even though I loathe egay/payfiend. These people accept credit cards though.

Michalis.Biochem

Fri Oct 29 2010, 09:27AM

Registered Member #3340 Joined: Wed Oct 20 2010, 07:28PM
Location:
Posts: 69

So it can be done!

Can i keep in touch with you in order to help me?

P.S i can't buy the one that Grenadier posted. It only ships to the US and i live in Greece

Adam Munich

Fri Oct 29 2010, 08:09PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

Well I'm sure you can contact the guy and ask him to send it to you. A small flat rate box can go anywhere for $14. I'll look for another that ships worldwide.

But why not just use a flyback? Get one of those small 5" black and white TV sets and pull the small flyback out. Then build a mini ZVS to power it.

Michalis.Biochem

Fri Oct 29 2010, 09:39PM

Registered Member #3340 Joined: Wed Oct 20 2010, 07:28PM
Location:
Posts: 69

Grenadier wrote ...

But why not just use a flyback? Get one of those small 5" black and white TV sets and pull the small flyback out. Then build a mini ZVS to power it.

That would be another good alternative, i ve searched for flybacks-broken tvs at my local hardware/repair shop but they don't seem to have any, or they simple didn't want to give be. Is there any other good source?
I ve also searched the ebay, but i didn't find any reasonable price.
Do you have anything to suggest?

Adam Munich

Fri Oct 29 2010, 10:15PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

Simply drive around on big garbage pickup! You may find a lot of TVs just being tossed out. Computer monitors have FBTs as well, and quite hardy ones too. I've pushed 1000 watts through a few without any failures. Though it was not for any extended amount of time.

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