Can i use a computer power supply to power audio amplifiers?

[Eva]

In these PSUs you can double the frequency if you want (at the expense of doubling switching losses), but it can't be reduced substantially as this may cause transformer saturation and control-loop instability.

[DigitalJunkie]

One consideration to add,that I havn't seen posted yet (But I only skimmed the thread ) is that PC supplies are usually grounded to earth/saftey ground,that is,the 0V rail is bonded to earth/safety ground.

In the first diagram in the thread,with the 2 seperate supplies for (+) and (-) voltages,this grounding setup would become an issue!
The power supply on the right would be shorted out!

You would need to 'lift'/isolate the 0V rail of atleast one supply (the right-most one in the diagram) if not both.

One more modification to make and/or trace to cut.

[destroyer X]

Some deviations from the main subject are natural, as they result from the dinamics of conversations.

One matter goes pushing another thing....but already related supplies and pulse width, or switching supplies.

thank you all, very kind from you to have this conversation here, a lot of informations are beeing good to me.

Line up
Your amplifiers will work fine, as you will have enormous power reserve....the supply can feed amplifiers producing more than 40 watts of power.

N Channel
Good to know that there are several threads to read about that subject...this will be great to me...now i have a lot of things to read and to learn....related to move..... related me, it is all rigth, if moderators decided this way, it is ok to me.

Eva
Mosfet things Ahahahahha!, me gusta mucho la verdad, i like those trues that we use in our words...our opinnion...in this case they may be problems...ahahahaha...very nice.
I have four 13009 in my junkbox...waiting the change to work.
Thank you by the schematics, now i will understand how those supplies works

Digital Junkie
Very good to have you here too.

regards,

Carlos

[Eva]

Destroyer X:

There is a lot to explain about these schematics, but be patient. I may even post waveforms from real PSUs if I have time. You may try to compare the AT schematic that I posted to the circuit of your AT PSU, and put values to the components.

[jackinnj]

Originally posted by Eva
The transformer of the 13.8V 40A power supply is strongly oversized, maybe because the author didn't calculate it properly, because he didn't got the self-starting thing right, or because he wanted to operate the cores at very small flux densities. With a proper design, the same power may be just obtained from a single E42/21/20 transformer. As you know, in my 32Khz power supply with a similar topology (full bridge really) I'm getting 1.8KW from just two E42/21/20 transformers (15V 125A output fully regulated). And my transformers are usually operated around 100mT (if I remember properly), quite far from saturation, while having a lot of free winding space.

A transceiver transformer has to be stable at about 100mA AND 20 amps (rx and tx) -- so both the transformer and output inductor have to be designed for two scenarios.

For our linear audio amplifiers the situation isn't that bad.

N-Channel -- somewhere Texas Instruments has a white-paper on a frequency hopping SMPS chip which greatly reduces the noise which is of paramount consideration in communications products (which is why people are finding the Drake R4C to be such a good receiver.)

[destroyer X]

AT supply.

This is good, that slowly you will giving us some explanations....giving time to reflections and to studies that i will have to make of your informations during the comparison of data with the AT supply sample i have.

ahora jo tiengo que descobrir este transformador referido, que tiene dupla salida simetrica que se une con diodos para la utilizaccion de las duas phases, con consequente acrescimo en la corriente de salida.

Now i will have to discover that transformer you made reference, the one that uses double output (( think), the simetrical output that is joined together using those diodes to have both phases joined increasing output current capabilities.

regards and thanks,

Carlos

[myhrrhleine]

Originally posted by lineup
Can I jump in with a question.

I was thinking of using only the +12V/8A
to make a low power Mini Amplifier.
I think it is not impossible.
And 8 Ampere is more than enough to power both channels.

I will NOT BRIDGE! (any such suggestion is a waste of your time)
Output will be like 2x2Watt/6Ohm in Class A.
A push-pull common collector output stage.
Idle current ~ 0.7-1.0 A. Per channel.

Are you saying it will not bridge?
or that it is your intent to not bridge?

If the latter, yes it can bridge.

[ekaerin]

Carlos,
I don't know much about computer PSUs but isn't the higher voltage
windings at low power.
Anyway, I would just try to ad as much cap as needed and listen to it !
If it stays quit its probably fine......
If the supply has any tendency to foldback it might not start with too
much cap on the output.

(I´m gonna be hanged by the experts for this approach, I know)

If you have a scope you may take a peak somewhre related to the
feedback-no oscillations-fine.

/ Mattias /

(Brave wired-half burned)

[ekaerin]

....By the way,
Speaking of big supplies, many amps.
The biggest supply I have contributed to was 54Vdc, 250A, 0.7mVrms noise wideband.
3phase wide input, 93.4% eff, 680W/litre power density, 65C ambient.
Input THD=1.6% at 50-100% load.

Need I say there where afew other guys involved.

/ Mattias

[destroyer X]

about that....maybe different related my imagination.

But i will not try anymore, i made studies and changes in the oscilating frequency and also in the transformer ratio.....i could double the voltage, but the oscilating transistors were too much hot.....also i forget to increase the output condensers, some of them explode.

They were substituted with a bigger voltage units...but to check if they were working cold, i touch something near the oscilator and i received a very violent electrical shock that left me without talk and breath for many seconds.

Well...i will continue with my old transformers.....at least, those ones i understand and i know how to avoid problems.... also i know how to construct and modify them.

Eva..... the electrical shock was enougth to me.... i will return to my old heavy transformers.

Thank you all guys...if you want to continue to study this subject, the thread is yours, go ahead and keep it nice the way it is .

hehe...i will prepare some transformers and forget those electrocution boxes for a while.

regards,

Carlos