Why turn a car stereo into a home stereo?

Because I can. Well, that's pretty much what it comes down to. On the other hand, it was justified. Our little Aiwa in the living room sounded great, but it was starting to suffer from the common Aiwa problem of the CD player becoming very fussy, and skipping on all but the best CDs ("best" meaning "in the best condition", not necessarily the best music - usually the exact opposite since bad music gets played less). Additionally, we had just pulled this car deck out of the '96 LeSabre because it was annoyingly bright at night, and we wanted something that would play mp3 CDs. The final piece of the puzzle fell into place when I was given a couple of old PCs that weren't good for much but parts.

First you need some things

Tools and supplies needed:

Electrical considerations

A car CD deck (any car radio for that matter) needs something like 9-14 volts of DC power to run. Household current is 120 volts, and AC. The best cheap conversion between the two is a computer power supply. It takes a decent one to power a car radio though. The really small 150 watt supplies found in some cheap, compact computers shut right down when you try to power up a radio. The supply I ended up using is not great quality, but it is at least full-size, and has performed well so far. I believe that I ended up with a 250 watt unit.

Different types of power supplies switch on and off by different means. Newer power supplies will turn on by holding a green wire to a black wire. This switches it on. Older supplies like the one I used have a mechanical switch on a length of wire, which physically turns on and off the household current to the unit.

A PC power supply puts out several different voltages (12v, 5v, 3.3v, etc.), but the one you really care about is the 12v. On your standard power supply, that will be any yellow wire. Black is neutral/ground. By attaching your radio's constant power (yellow, usually) and ignition power (red, usually) to the yellow 12v power, and the black radio ground to the black power supply wire, your radio should power up. If you have speakers hooked up, it should play and function just fine. If you made up a nice little enclosure, you could run it just like that. Easy enough, right? Yes, unless you're anal like me.

radio in progress
Power supply and switch mounted
radio in progress
The speaker terminals and switch

The problem with the above setup is that if you turn off the power supply, you lose your station presets, and all other settings. If you leave it on, it's constantly making fan noise and burning power (how much, I'm not sure). After much thinking, I decided on a compromise solution. A double throw, double pole switch does several things. When it's in the "off" position, it's sending 5v to the fan instead of 12, so the fan runs slowly and quietly, but still keeps the power supply plenty cool. The 12v power to the radio's red "ignition power" wire is off. When the switch is turned on, the fan is given 12v, the radio's red "ignition power" wire is given 12v, and a LED light circuit is given 12v. In this way, the complete unit is quiet while "off", but the power supply is still providing the radio with standby power, just like a car battery would while you're not driving.

WARNING: Be careful when working on a power supply! First, unplug it, obviously. Even unplugged however, power supplies contain large capacitors. These will hold a high voltage, potentially lethal electrical charge for a very long time. Either discharge them with an insulated metal object like a screwdriver, or very carefully avoid touching anything while working. Or do both, like me. If you are unsure of your ability to avoid serious injury or death while working on a power supply, don't mess with one.

In order to switch the voltage to the fan back and forth between 5v and 12v, I had to open up the power supply, unplug the fan's connector, and route the wire to the outside of the power supply case. My power supply also had far more wires than I ever would need to power a car radio, so I cut every unused wire off flush with the circuit board while I had it opened up, leaving only what I would actually use.

To connect an antenna, I found a large nail that was just the right size to "plug in" to the center hole of the antenna jack, and soldered a wire to it. That wire I then attached to a metal clip on the back of the case, where I can connect a longer antenna wire to get reception. This setup works quite well. Oddly, it works best if I make a loop of the wire, having both ends in the clip.

Speakers connect to the rear of the case using a spring-terminal setup from Radio Shack. It attaches with two screws to the case, and the speaker wires from the radio are soldered to the metal leads on the back. Since this isn't a car, you'll probably want to chose either front or rear speakers, and not use the other leads for anything. That said, you could possibly make this a four-speaker system very easily, if you had the extra speakers. I wanted to just use the two nice speakers from the Aiwa though, so I didn't bother.

Building a decent looking enclosure

radio in progress
Finished at last!
radio in progress
The less-pretty side

The case took the most time. I considered many building materials, including thin plywood, paneling, plastic sheet, and random pieces of furniture. You could easily build this into an end table, or kitchen cabinet, or something. My final solution was a combination of the computer case that the power supply came out of, and scraps of pine board that I had left over from building some shelves in our closets.

The top and sides consist of the top/front of the PC case. It's just wide enough to clear the radio. It was too high and too deep, so I cut it to size with an electric jigsaw. Those were some challenging cuts to make. There is probably a better tool for the job, like an air cutoff tool or something. The front, bottom, and rear parts of the case are 1" thick pine board. Most of that was cut with a hand saw, but the rear was cut using the same jigsaw. I won't dwell on the case too much, since that's really personal preference. One thing you will want to remember though is that since the power supply fan is blowing air out, you will need an opening to allow fresh air in. You'll see that on my enclosure, I just left a large gap at the top of the rear. In case you think I'm just a lousy woodworker, I did that intentionally to allow cooling air inside.

I mounted the power supply switch onto the rear side of the case. I don't really use it, but it's nice to be able to turn the whole thing off if I want to. I was even able to reuse the large tan button from the case.

My case is about as compact as you can make it, and still have everything fit. I suppose you could make it slightly shorter, and slightly less deep, if you used thinner materials than the 1" thick wood that I used. Other than that though, my setup is quite a tight fit in there. There might be 3/4" in depth and height to spare, if I had to guess.

End results and thoughts

radio in progress
All set up and working!

The finished radio looks and works pretty good. The sound is about what the old Aiwa was (same speakers). The reception is almost as good, but not quite. As hoped for, the power supply fan is nearly silent while the unit is switched "off". It does become somewhat louder than I want it when it is turned on. When the radio is turned down, you can hear the fan. Also, the fan bearings are crapping out on it, so it's really noisy now when you first start it up (just like some computers). When I replace the fan, I might either add a resistor to the 12v fan circuit to slow it down a little, or just have it run at 5v even when turned on. It may get warm with less air circulation though.

Updates

4-29-08 - With continued use, the unit has gotten dusty inside due to the constant flow of air. I might try to filter the incoming air somehow, eventually. For now, I've just blown it out.

4-29-08 - The power supply fan also became noisy with time. The poor over-worked bearings finally bit the dust. It is still very quiet at the 5 volt speed however, so last night, I re-wired it to always run at 5 volts, never at 12 volts. It hasn't started on fire yet. Actually, I haven't noticed any ill effects. It's just quiet. I have a feeling that the radio just doesn't draw that much current while powering only two channels at moderate volume levels. Maybe if I really cranked it up, it would need more air. Actually, some people have successfully used the -3 volt and +5 volt wires to effectively create an 8 volt power source for their fans. That might be the ideal solution, but alas, I cut off any unnecessary wires long ago. I think this will work fine for me, anyway.

8-6-08 - The power-supply fan apparently stopped running altogether some time ago. We didn't notice it, because it was quiet now that it was running on only 5v. Anyway, this caused the power supply to overheat, and die. It still lights up the LED about half-way, but that's all she's got. Toasted. I'll have to find another power supply, with a better fan, and bring it back to life.

11-23-08 - I never did find another suitable power supply for free, so the radio just sat there. Then one day, I was kindly given a load of surplus electronic goods, including an old Pioneer A/V receiver which only supports 3-channel surround but is still just fine for stereo use, and a Pioneer 6-cd cassette changer, and a Pioneer two-tape deck, and a Bose "Acoustimass 5" speaker system. While the old system sounded fine, the new sounds noticably better, and can do more. Needless to say, the "project" is replaced for now. It may yet see the light of day, but it's not a priority at the moment.

Feel free to email me if you have any questions or comments about this project.