Tired of having a couple of cables unused behind my dash, I made up a Y cable, two RCA plugs to a mini stereo phone jack, and attached the RCAs to my sled's aux inputs and mounted the other end inside my glove compartment. (I have an E30 BMW 325e, which has a gaping maw of a glove compartment.) Now I can hook up a variety of portable players and play it through the Aux inputs. Very nice. (Now if I can just figure out what the hell the empeg's screen is telling me when in aux mode. I'm sure it's in the FAQ.)

Anyway, it'd be really nice to also be able to hook power up to said portable devices, but I'd have to have something that would allow me to change the voltages so that I could hook up different devices. I suppose I could hook up a variable resistor of some nature, but that seems like a bad idea for a good number of reasons. Being able to attach a real device that does that would be super, but I can't find one that has an appropriately small selector. RatShack's seems to have a dial about 2" in diameter. Anyone have a solution for me?

Many (low quality) multi-voltage car adapters with a cpacity up to about 1A are nothing more than a bunch of series connected diodes with a switch to connect more or fewer in series with the load. The smaller the wanted output voltage, the more diodes (each drop about 0.8 to 1V). Better, but not great, stability compared to a resisitor which only works properly if the load doeasn't wary it's current consumption.

I'd look into building a small adjustable power supply. Not much more than an IC, a few caps and a potentiomenter these days...

/Michael

You might check some catalogs or online retailers that sell car/airplane powered dc adapters for laptops. I have one I bought a couple of years ago that is perfect. I cant remember where I got it but these are the basics. It takes a 12 - 16 VDC input. via either a cigarette lighter in the car or with the additional adapter via the power plug on the seats of some of the newer airliners. The brick peice of it has an adjustable pot that can adjust from around 6 - 20 VDC output. The output end has a standard removable end (2 pin style). You can get dozens of different end pieces from Radio Shack as they are the same style end pieces that Radio Shack has for their AC adapters. I paid about $100 for mine. It sounds like it could be perfect for what you are looking for. Just hard wire the input side and feed the brick and output wire into the glove box.