car stereo but at home? power inverter?

[mike5721947]

well im bored and am wondering how hard it would be to build a inverter to switch 120v ac to 12v dc so i can run my car headunit and speakers in my room. im thinking if i rip apart an old computer and take the box out of the back top of the tower (i think its a inverter that switchs 120 vc to 12v dc) or is there a easier way?

[Hi Tech]

12V Motorcycle battery, and use a Trickle Charger when it gets too low for power!

I do those kind of setups in my garage, all the time, just to test out radios and speakers, while they're out of the car!

[mike5721947]

well im wanting to get this to be permanent (until i get my car working) i was thinking of a tranformer that plugs into the wall but i need to know how much amps, and other stuff a car stereo get imputed.

[sierrap615]

Originally Posted by mike5721947

im thinking if i rip apart an old computer and take the box out of the back top of the tower

problem with that is a standard computer power supplys don't put out the amprage, of the three i have sitting around here two put out 4.2 amps and 12 volts and the other 3 amps at 12 volts. but they work fine if you need a 5 volt source(two put out 18 amps at 5 volts, the other 15 amps at 5 volts) so you would need to ether buy a special higher amp power supply for a computer, make one if you have the skill, or find a different style power supply(like above motorcycle battery idea) quite a few things work off of 12 volts.

[mike5721947]

what amp rating do i need though?

[sierrap615]

depends on the wattage of the stereo.

amps X volts = watts

IE - a 100 watt stereo on a 12 volt system pulls about 8.33 amps. however, how many amps a stereo acculty pulls changes all the time, with the change in the sound output. ever see a large stereo hit the bass hard? it pulls so many amps the electrical system is drained for a second, hence the headlights dim. a capacitor can help even out the electrical surges, and in the case of a stand-alond system like you are talking about i would still include a battery for the some reason. you also want to be able to supply more amps then need so the power supply isn't always working at full output and again you are protected agaist power surges. factior in a extra 20% is a safe rule of thumb. so for that 100 watt stereo pulling 8.33 amp you should design your system for closer to 10 amps.

another option if you don't know the wattage is to go by the fuses, I.E. my stereo uses two fuses, one 5 amp and one 10 amp. so you then need at least 15 amps, again add a little more to be on the safe side. now i know my stereo doesn't pull 15 amps, as the manufactior also factiors in that extra 20% or so, but still, better safe then sorry.

[curtis73]

Excellent reply as always, sierrap615. If you go to Radio shack they have DC converters for 12v that go as high as 25 amps. Here's a link to a 15 amp source that should do quite well:

http://www.radioshack.com/product.as...%5Fid=22%2D508

[williamskinner16]

When my brothers and I were kids/early teens (4 brothers) we had homemade enclosed bunk beds built of 2x4s and 3/8" OSB/Pannelling they were pretty cool and best of all we had car stereos (well 8-tracks scavanged from junkyard cars!) and they were powered by power inverters. For a 12 year old, I thought they were awesome. Lately have often thought, why doesent someone offer a quality head unit able to plug into the wall in your livingroom and unplug to plug into the car when you are ready to roll. Anyway I saw this post and it brought memories back. It can be done.

[TheSilentChamber]

Speakers deisgned for automotive use arnt going to sound good in your room. But yeah power inverter.

[Jimmy Neutron]

the best part of a setup like that, is the fact that car tuners work SOO much better than the ones for home use. I was thinking of making a component set up, like making boxes for som 6x9's and a head unit, mostly to pull in stations, been toying with the idea for a while, the cost of the transformer was the only barrier, and when youre making dc from ac its called a transformer, inverters go the other way.

[TheSilentChamber]

Dont bring up old threads.

[CBFryman]

incase anyone is wondering that does read this though, search in the car audio section, i did a write up on how to turn a PSU into a 12v power supply, a 300w power supply will yeild 15a at 12v but not for any sustaing ammoutn of time. i have 2 in parallel and with an inefficent class a/b amp i can get around 180ish watts.

no a 100w system does not pull 8.33a... stereo equiptment is quite inefficent, even the most efficent of amps are onaly around 70%. most multi chanel amps are a/b or b which may be around 40-50% efficent....meaning a 100w system would pull around 17a just for audio...
if you have an old class A which are very inefficent (and make good space heaters) they are around 20% or so efficent... meaning 100w would take over 40a of current.