FUQ (eff -yu - cue) - FAQ's with an EDGE

Tagged As: Power Supply Amp

Question:
I'm building a power supply to run a 12vdc car stereo in my room. The power amp is a 300w ADS Power Plate 300. At 12.5v I need a 24A supply? This seems wrong somehow.

Answer:
You will very likely need a hell of a lot more amps than a LM317 @ 1.5A can deliver. Also it is very unlikely that your surplus 12 volt battery charger can deliver enough current to be useful in building the kind of heavy duty power supply that is certainly going to be required for your set up....... 24 amps at an absolute minimum with an actual requirement of almost double that if indeed your 300 watt amp can really deliver 300 watts RMS ... and that you intend to run it at high volume levels and are expecting clean performance. To build a safe and proper 12 volt power supply that can deliver enough current for your apparent needs is not going to be an easy, novice task, nor will it be cheap. Do a search on the internet for power supply and electronic equipment suppliers and most certainly Ebay for power supplies that are already built, you can most probably buy something cheaper than if you built it.... and if you purchase a quality built unit it will likely include important safety shutdown features to protect your stereo equipment, your home and the power supply against over-voltage and fire starting short circuits.... very important when dealing with this kind of metal melting current. A possible low-tech solution for you would be for you to use that 12 battery charger that you have to keep an automotive battery continually topped off.... then you can run your high power stereo system through a suitable fuse directly from the battery. If the charger is an automatic type that will reduce to a trickle charge when it senses that the battery reaches a fully charged condition you can leave it hooked up all the time whether you are using the stereo or not. The main drawback to all of this would be that if you intend to run your stereo at very high volume levels on a continuous basis the battery may run down after approximately an hour or so unless you give it a chance to charge up with the stereo shut off or turned down to easy listening levels.