Building an amplifier power supply using a voltage doubler and LM317?

[hornloaded]

I was considering purchasing a kit such as: QKits Electronic Kits: FK656, Power Amplifier Kit OTL 30W (Mono) R1%

To use as the output stage for an amplifier. I just won an ebay auction for a 40VA 24CT transformer. Now obviously the voltage output of the transformer would not be high enough for that kit. So I was thinking about building a voltage doubler circuit. And then after the circuit, I would use a LM317 for regulation.

Would this be a bad idea to regulate the p/s? The max output current of the LM317 is only 1.5Amps, so it would be cutting it pretty close. I wouldnt need the full 30 watt output of the kit, even 20 watts would be fine.

It would be driving a single 8ohm guitar speaker.

[hornloaded]

Has anyone used a Voltage doubler circuit before?

[Nelson Pass]

It takes a lot of capacitance and probably more transformer
to build a voltage doubler good enough for the power stage
of an amplifier. Normally this technique is reserved for low
current use, as in creating higher rails for front end circuits.

[hornloaded]

Ah, that makes sense. Even if you used a full wave bridge rectifier in the doubler section, would it be a lot less efficient than a standard power supply?

[h_a]

if you used a full wave bridge rectifier in the doubler section

That's not possible, because that's the essential part how the voltage doubler works.

Have fun, Hannes

[bobodioulasso]

You need a 2x20v transformer .

[hornloaded]

Originally Posted by h_a

That's not possible, because that's the essential part how the voltage doubler works.

Have fun, Hannes

What about this example:

File:Full-wave voltage doubler.svg - Wikipedia, the free encyclopedia

[Greg Erskine]

That's just normally regarded as a full-wave bridge rectifiier in my books, but I can see why it is called a voltage doubler. Do you need +ve and -ve rails? YES

The simplest solution, is just buy the right transformer.

[kevinkr]

Check out Antek toroids - I am sure they make something suitable for your application at a price that will surprise you. (I've been using them for years.)

Antek - Your reliable source of transformers, power supplies, and more. I think a 100VA transformer AN-1232 would be adequate for this application. See page here: http://www.antekinc.com/details.php?p=42

[bobodioulasso]

a 2x20v xformer will give aproximatively
20v x 1.4 = 28v DC
20v x 1.4 = 28v DC
2 x 28v DC is ok for a 30 w amp (8 ohm supposed ?)

I wouldnt need the full 30 watt output of the kit, even 20 watts would be fine.