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Zack

Fri Jan 21 2011, 02:50AM

Registered Member #3624 Joined: Mon Jan 17 2011, 01:08AM
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Posts: 25

I was wondering if I could use this circuit to get 2-3 kv from a wall transformer, powered by a 12 volt lead acid or 9 volt battery. If not, does anyone know of something similar that I could use, or modify the circuit to make it work?

Adam Munich

Fri Jan 21 2011, 02:58AM

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

You'll need to increase the current that the circuit can provide. A mosfet could do the job easily. The main problem is that those transformers' insulation isn't rated for 3kV, and they may burn out. A 9 volt also cannot supply nearly enough current, a lead acid is the better option.

May I recommend the light dimmer + ignition coil circuit? It can provide some nice sparks.

Zack

Fri Jan 21 2011, 03:11AM

Registered Member #3624 Joined: Mon Jan 17 2011, 01:08AM
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Posts: 25

Unfortunately there isn't any place near my house that sells ignition coils at a reasonable price. Are there any 8-pin mosfets that would work for this? Also, what I would like to do with the transformer is power a cascade, so I guess I wouldn't need that much power. Can it withstand 1kv?

RichardK

Fri Jan 21 2011, 09:45AM

Registered Member #3605 Joined: Wed Jan 12 2011, 04:46AM
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8-pin MOSFETs? You mean a MOSFET in an 8-pin DIP chip? do they even make those?

Adam Munich

Fri Jan 21 2011, 11:37AM

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

Have you checked the junkyards?

And I've no clue what an 8 pin fet is.

Antonio

Fri Jan 21 2011, 07:00PM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

Transformers canÂ´t be operated much above their designed voltage ratings because the core saturates due to excessive magnetizing current (the current that flows without load, and is proportional to the input voltage). This can be circumvented by operating at higher frequency (just keep the ratio voltage/frequency constant for one of the windings), but the transformer may become excessively lossy at high frequency or the insulation may be destroyed if excessive voltages are used. Normal insulation is for 300-600 V only.
To experiment with high-voltage transformers, it's better to find an ignition coil or a discarded CRT monitor or TV and take the flyback transformer from it.

Zack

Fri Jan 21 2011, 09:55PM

Registered Member #3624 Joined: Mon Jan 17 2011, 01:08AM
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Posts: 25

I built a 15 stage cascade with 0.1uf caps at 400v each, and I would like to power it somehow, so are there any other possibilities?

genious 7

Sat Jan 22 2011, 03:52AM

Registered Member #2887 Joined: Sat May 29 2010, 11:10PM
Location: Panama City, Panama
Posts: 107

Connect it to mains? (Through a suitbale isolation transformer, of course)

...or use those car inverters that spit 120v from 12v. Bear in mind that the frequency is 60hz, low for a multiplier. Due to this, tis won't give maximum power, but it is a start.

Since the cascade is made using 400v capacitors, using 2kv would blow it all. Using mains (120v, 170 peak) would be the simlest way. Bear in mind that if you live in a 220 v countrry, get a stepdown to 120v or else you might risk into blowing the capacitors.

Zack

Sat Jan 22 2011, 06:31PM

Registered Member #3624 Joined: Mon Jan 17 2011, 01:08AM
Location:
Posts: 25

Yeah, I tried connecting it to mains, but it makes only a 5mm spark every 5 seconds or so. So do you think I could use a flash camera inverter?

quicksilver

Sat Jan 22 2011, 08:34PM

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

Check 555 circuits for automobile coils; as they may come closest to your quest to use the 555 as a means to produce a spark.

The standard dimmer / cap to a (automotive) coil is a sure bet. but if you're wed to the 555 concept there are MANY conjunctive circuits that would work well with such a coil.

If your issue is the voltage per se' many MOTs would get you there (and then it would be a matter of altering frequency if necessary; as again you'd still have 60Hz). I have also used a 78w 3ohm ceramic resistor to drop the current of the MOT while maintaining it's voltage but when using very high wattage ceramic resistors; heat is a serious problem when the usage is applied to arc, etc. I don't have the math handy but it's pretty close to cut the current fairly half way, making it a candidate for less expensive circuits by the out-lay of money to get a big hollow core resistor.

VERY old radio transmission equipment is your friend.

I have seen absolutely what you are looking for as a military transformer it's input is 120Vac and output is 375V .040 ma; it was a surplus Radio unit and standard mil-type with "upside-down" threaded connections. They are out there.

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