# ac psu

Discussion in 'General Electronics Chat' started by ariemeir, Apr 2, 2013.

1. ### ariemeir Thread Starter Member

Jun 24, 2011
68
1
Hello guys ,

I'm looking for a simple way to build an ac power supply capable
of generating roughly a sine wave with 500-1000 amplitude (1000-2000 p2p).

The required current is 1-100ma and the frequency range is roughly 1-10khz.

Since my intention is to use this device for a quick lab experiment, i am looking for a quick and dirty diy solution i can rig using standard components and perhaps a couple of trips to a local salvage depot.

I've searched online and it seems that tesla coil power supplies and microwave transformer based supplies are the common ways to go about my problem.

I am wondering if some sort of simple flyback transformer wouldn't be more appropriate for my goal.

Regards,
Lenny

2. ### #12 Expert

Nov 30, 2010
16,248
6,745
Quick and dirty? Got it. Use a standard signal generator to feed an audio amplifier and calculate an output transformer for it. You need 70 to 140 watts after the transformer has had its losses, so try to find an amplifier about 30% higher in watts. About 200 watts should do.

Then again a 150 watt step-up transformer isn't cheap and you're going to be sifting through specs for a while to find a transformer you can run backwards.

3. ### ariemeir Thread Starter Member

Jun 24, 2011
68
1
thanks #12,

the general flow makes sense.
Would you mind sharing how did you calculate the required amplifier power ?
I am thinking of getting one of these:
http://www.amazon.com/LP-2020A-Lepa...UTF8&colid=2AWAEWQDTVCIA&coliid=I8LWKPBYCBBC0

I've also found this unit:
http://www.amazing1.com/transformer-4000v-15ma/

which claims to supply 4000v at 15ma. What i think i am missing is that they
claim it works from a 12vdc at 1a. 12*1 = 12w , and 4000*0.015=60w.

Could you point out where am i wrong ?

Also - how does the frequency i operate on affect the behavior of the step up transformer ?

Thanks for the advice,
Lenny

4. ### #12 Expert

Nov 30, 2010
16,248
6,745
The step up transformer must be designed to work at your frequencies. That is why I'm talking about audio range amplifiers. If you do as I suggested, you will need an audio range transformer to do a step-up at 10KHz and it will probably be an output transformer from a vacuum tube amplifier, run backwards.

This isn't the only way, but it's what I have in my shop. For me, this is quick and cheap.