Audio transformer as step up transformer

On a sunny day (Fri, 4 Dec 2015 10:24:32 -0500 (EST)) it happened bitrex wrote in :

Yes

I have used some of those small audio transformers for just that. Losses my be higher at 30 kHz though, aouside the band they were designed for.

Sure, as long as you don't break down the insulation. A couple of hundred volts peak should be OK for most audio transformers. The frequency will need to be pretty high, not 60 Hz.

Use a Cockroft Walton thing to get higher voltage.

That makes 1200 volts from 5 volts.

Why use an audio transformer when there's purpose-built ones out there to buy?

On a sunny day (Fri, 04 Dec 2015 16:23:25 GMT) it happened Jan Panteltje wrote in :

PS

in 3.8 V out 400 V 1:10, flyback pulse used, watch polarity, That is a conrad.nl audio transformer. Of course you have to watch for high voltage breakdown. And watch your PWM pulse width. and and and

works 24/7 now for a year or so..

I obtained a bunch of them at a very reasonable price: $0

If it's fo' free, it's fo' me.

I've seen that done before, stepping up a battery-powered oscillator's output to a higher voltage which is then rectified and filtered. It worked well enough to run a bunch of NE-2 neon lights.

If these are the little ones that used to be common on old, cheap transistor radios (size about .5 inch cubed) then the bandwidth is about

Good reason!

The very fine wires inside won't handle much voltage at 30 kHz. I'd say that 100V is lucky.

CCFL transformers are perfect for 30 kHz and high voltages.

The gold standard was the radio shack ones. They had long insulated leads and the insulation was rated to 2500 volts. They are now sadly unobtainum.

I just built a power supply using ones I bought off of eBay, which are

Using a 2n2222 transistor, 12 volts in and two stages of voltage doubler (.01uf capacitors, fr107 diodes), I was able to get enough output to charge a 0.1 uF capacitor at 400 volts, regulated by two 200 volt zeners in series.

It works, it does not short out due to overvoltage and the parts were all very cheap. The listing is no longer active, but it was for "5pc Audio Output Transformer OPT-14 EI14 0.25W Impedance=523.-0-523. : 12.3 ohm"

I bought 20 of them for a $1 each including postage.

I expect you can get similar results from yours.

The other possibility, depending upon the impedance of the transformer windings would be a power supply that uses it as a "boost" coil.

I have seen various circuits on the web that use coils which range from

Enough to run a geiger counter.

Geoff.

That's great news - thank you!