Alternate use for power supply

[Davor]

My goal is to hook up a car amplifier to a regular wall outlet. Considering the amplifier runs at 300 watts RMS, I need a pretty good amount of power. I have done this once before using a cheap old computer power supply but it was for a much weaker amp. What I did was cut all the positive power wires and connected them together. Then did the same with the ground/negative wires. Because I only ran it for a few minutes at max, I was unable to see if there was any possible long-term damage to the power supply or the amp. I don't really know much about how exactly the power supplies work so I was hoping someone would be able to give me some help on this. Thanks.

 

[Evadman]

Some of the higher wattage ones will put out 15-20 amps on the 12v line, but they are made to supply most of the wattage to the 3.3 and 5v lines.

 

[Stealth1024]

Radio Shack has just what you're looking for. I purchased a 3 amp sustained (7 amp max) 13.8 volt rectifier/transformer a while ago for a reasonable price and have loved it ever since.

 

[Davor]

Isn't watts=amps x voltage. This would only give a sustained 41.4 watts and can only urge to 96.9 watts. I need more power than that.

 

[IamDavid]

You can actually do this? Run a car amplifier off a computer power supply? Please explain..

 

[Geniere]

Twisting the 12vdc lines together with the lower voltage wires makes no sense. Since the PSU didn?t burn up, presumably the lower voltage regulators shut down. I would bet the only output was from the 12vdc line.

In any case, up to the amperage (wattage) limit of the 12vdc output, the supply can be used for anything requiring that voltage. If it's an ATX supply, you'll have to short pin 14 to 15 to turn it on, and even then some require a proper load to turn on.

regards

 

[Davor]

What does short pin mean. I don't know too much about electronics so an little more explaining would help me a lot.

 

[KenGr]

In the ATX power supplies, when you plug them in and turn on the main switch, no output power is supplied to the DC wires except for a small control current to the power switch leads. When these are shorted (by pressing the "on" button on the front of the case, voltage is switched on for the other DC power leads.

 

[Geniere]

 

[Geniere]

OOPS - Try again

Don't do anything while the PSU is plugged into the wall outlet, as there is 120volts inside the box! Don't remove the cover!

By shorting the pins, I mean connect the pins together. If you cut the wires from the connector, then connect together the wires that went to pins 14 and 15. Stand back and plug it in. The fan should turn on, if not it means that the power supply needs to be connected to a load, i.e. a motherboard or a resistor on the unused voltage wires.

The supply, if you get it to work, will likely only handle a 60-70 watt audio amplifier. If your amp is rated at 300 watts rms then forget it. If its rated at 300 watts "peak music power" or some other marketing ploy, you might be ok.

 

[Evadman]

For the most part, connect the green wire and any black wire to get the PWS to turn on. Be aware ( as was mentioned ) that there usually has to be a load on the 3.3 and 5v lines for it to work correctly.