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Masih

Wed Nov 05 2008, 05:07PM

Registered Member #1213 Joined: Fri Jan 04 2008, 09:40PM
Location:
Posts: 14

Hi friends

I want to build an AC high voltage source to provide 5 to 35 KV of High Voltage. I tested Mazilli circuit with a flyback transformer. it works well but DC output. now I want to buy an old TV transformer but don't know if they can provide my desired output(5-35KV).
whats the maximum output of an old TV Transformer?

can I use an ignition coil for this purpose? can it deliver my desired output?

other ideas are highly appreciated

flannelhead

Wed Nov 05 2008, 05:22PM

Registered Member #952 Joined: Mon Aug 13 2007, 11:07AM
Location: Finland
Posts: 388

Ignition coils can deliver well the output you need. You need a special driver for them.

Also old AC flybacks work great for this purpose. They are pretty rare nowadays, though.

What kind of a frequency do you want? Ignition coils operate at a frequency range like 20Hz-3kHz and flybacks at 17kHz-50kHz.

Dr. Dark Current

Wed Nov 05 2008, 05:22PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Yes they can, color TV transformer ~8 or ~30kV, B/W TV transformer ~15kV.
Or you can wind one yourself, 10kV is easy.

Masih

Wed Nov 05 2008, 05:51PM

Registered Member #1213 Joined: Fri Jan 04 2008, 09:40PM
Location:
Posts: 14

as I said before the maximum output will be 35KV. So I think old monochrome TV Flyback cant cover my required range.

Is it possible to drive an ignition coil by an ZVS Driver?
I've drove the ignition coil by dimmer but its very noisy.
actually I prefer to use a flyback transformer. if its possible

LithiumLord

Wed Nov 05 2008, 09:00PM

Registered Member #1739 Joined: Fri Oct 03 2008, 10:05AM
Location: Moscow, Russia
Posts: 261

Don't forget that you can fit two secondaries on a generic TV core.

Masih

Wed Nov 05 2008, 09:33PM

Registered Member #1213 Joined: Fri Jan 04 2008, 09:40PM
Location:
Posts: 14

Please Explain more. you mean driving two flybacks in series driving by a ZVS Driver?
also let me know whats the arcing manner of AC an DC, Whats the deference?

Arcstarter

Wed Nov 05 2008, 09:48PM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

Masih wrote ...

Is it possible to drive an ignition coil by an ZVS Driver?

Yes, it is. All you do is put the 5+5 turns primary on an old flyback ferrite core and have a few turns for the secondary. You will need to experiment with the secondary turns though to get the required output. With more secondary turns you will get high voltage but lower current and less secondary turns gives less voltage but more current.. So just start with a few turns and subtract or add turns until you get the needed voltage output.

Also, remember you will have to change the capacitor of the zvs to get the right frequency. This would probably be a few tens of uf's but i really do not know. Just change all variables(capacitor size, primary turns, secondary turns, input voltage) until you get desired performance.

And the good thing about using the zvs in this way is that not only can you change what the input voltage to the ignition coil is, but since you are using the ferrite core transformer to turn the center tapped winding into one winding, any voltage spikes produced from the ignition coil will not get into the zvs driver, unless it is high enough voltage to arc through the secondary windings of the ferrite transformer, through the ferrite core, and then through the primary insulation into the driver. I am sure you may still get a little voltage spike that goes through the transformer but it will be ALOT less that it would without the ferrite transformer.

You want the capacitance of the zvs driver to be high enough for the frequency to be around a few khz, probably 3khz or less. Since the frequency will be much lower than the frequency the ferrite core is made for it may not be extremely efficient but it will still work.

...

Wed Nov 05 2008, 10:58PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

Instead of using a flyback core to couple into the transformer you could also use 2 series inductors (instead of the single one attached to the midpoint) that are both wound on the same core (make sure they are both wound in the same direction), and connecting them from v+ to both terminals on the primary on the coil (the rest of the circuit would remain the same). Just remember that you can't run an iron core and high frequencies

mikeselectricstuff

Thu Nov 06 2008, 12:32AM

Registered Member #311 Joined: Sun Mar 12 2006, 08:28PM
Location:
Posts: 253

Capacitance on the output is a major problem for generating HVAC at flyback transformer type frequencies as even a few pf draws substantial power - this is why modern flybacks use funky tricks with diodes.

LithiumLord

Thu Nov 06 2008, 12:49AM

Registered Member #1739 Joined: Fri Oct 03 2008, 10:05AM
Location: Moscow, Russia
Posts: 261

Masih wrote ...

Please Explain more. you mean driving two flybacks in series driving by a ZVS Driver?

No, I mean this:

(a pic of my first driver, a 555-based push-pull - you can see a double-secondary flyback to the left)

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