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| Home-made car sound system http://www.runestorm.com/forums/viewtopic.php?f=6&t=43625 |
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| Author: | Tyster [ Mon Oct 08, 2007 10:45 am ] |
| Post subject: | Home-made car sound system |
Perhaps you've seen products in stores and in catalogs that enable you to plug in your portable music player (iPod, MP3 player, etc.) directly into your car's speaker system. These cost about $200-$300. Alternatively, you could se a $10-$20 tape adapter, which has a normal stereo jack you plug into the headphone port of your portable player and a cassette on the other end to plug in your tape player. That, however, introduces a faint static noise in the background and degraded music quality (but not too noticable unless you're listening to Hydan or something like that). Here's where my idea comes in. Theoretically, you could simply wire your player directly into your car sound system. if my understanding is correct, your car's dashboard-mounted CD/tape/radio player has a single, low current, output signal that gets fed to the amplifier in your car, which boosts the signal to work the speakers. If you know a little bit about electronics, you could rig a wire that has a stereo jack on one end, and on the other end, the 3 wires (left, right, ground), go to the amplifier. However, you would need to know the details about the kinda currents and voltages the amplifier uses. Correct me if I'm wrong, but the amplifier does not alter the voltage it takes in because that is controlled by the music, which is a sequence of scaled voltage pulses. However, the current controls the volume, so you would want to make sure the the amplifier does not draw more current than your portable player can handle; mine can handle 400 mA, for example. You can simply plug in an DMM to measure current through the amplifier's input and see what maximum volume would draw the maximum current for your player, then turn the volume down a bit and keep it there. After that, simply take the wires from your rigged sterio jack wire and tie them in parallel with the other inputs from the dashboard-mounted device. 3 feet of wire and 3 wire ties should do the trick (under $1.00). I havn't tried this yet, but plan to do so in the near future. Jsut speaking my thoughts as of now... |
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| Author: | Captain Xavious [ Mon Oct 08, 2007 10:51 am ] |
| Post subject: | Home-made car sound system |
We need more do it yourself threads like this, they're always interesting to read, maybe inspiring to sometime do, and are just plain great ways to make something cool and possibly save some cash. I have no clue on how electronics work, but if that works, that'd be pretty awesome. Good luck on it. |
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| Author: | cyberax [ Mon Oct 08, 2007 1:32 pm ] |
| Post subject: | Home-made car sound system |
mmm....sounds interesting...DC should reply here...he's not too bad with electronics... BTW, I hope both units are out of warranty, cause you're going to void thhe warranty! |
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| Author: | Tyster [ Mon Oct 08, 2007 4:11 pm ] |
| Post subject: | Home-made car sound system |
I think I made an error. My dad, who seems to know a bit about this stuff, said that the voltage controls the volume. Given that, Here is how you make sure you don't fry your player. First off, note that this process will not guarantee that your car's amplifier will not be damaged, but I have a gut feeling it won't. Take any of my advice at your own risk. Use the fundamental laws: V=IR and P=IV, where P is Power, I is current, and V is Voltage. Your main interest is in making sure that some maximum power is not exceeded. Some manipulation gives this equation: P = R * I^2 So, with your player turned unplugged, use a DMM measure the resistance between one of the output contacts and ground, on the player's sterio jack. This is your value for R. Then, set the volume of the player to 0 (or the lowest volume). I know my player gave me a maximum output current (such as my 400 mA), so you can calculate your maximum power that your player can put out without damaging itself using the equation: P=R*I^2. Almost done with the math; just one more thing. We need to know the maximum voltage. We know resistance, max power, and max current, so we can find voltage using the equation: V = I R With your player's volume set to the lowest possible value, plug in the player's stereo to the amplifier. Take the black wire from the DMM and attach it to the ground wire form the player. Attach the red wire from the DMM to one of the player's output wires (not ground) and set the DMM to measure voltage. This will require some wiring skills. From the above equation, you now have your maximum voltage. Start playing some lout music on the player and slowly increase the player's volume and stop when you get near the maximum voltage on the DMM. Whatever volume your player is set to at this point is the maximum volume you should use. In conclusion, this little do-it-yourself project could be a cheap solution to good quality sound directly from your portable player, without buying an expensive dashboard-mounted device or even more expensive iPod gimmick. Most of this work is just to make sure you know you're not gonna fry your player, but this does not indicate that your car's amplifier is safe. However, my gut says it'll be fine as long as you don't turn up the volume so high your ears bleed. If you can, check your car's amplifier for maximum input power, current, and voltage. The only tools you should require are screw drivers, pliers, wire strippers, wire clamps, about 3 ft. of wire (or more, depending on where your amplifier is located), and a male stereo jack that fits your portable player. I haven't tried this yet, but plan to do so in the next month or so. |
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