[coyote65]

hi all,
I tried to plug the power of my cmoy in the 12v car plug, maybe I was wrong with positive and negative and something is broken so I cannot hear anything from the out plug of the cmoy.
Does someone tell me what part probably is broken? (and I've to replace)

thanks everybody and sorry for my bad english.

 

[FallenAngel]

With the power output of a car battery, I'm very surprised nothing blew up. It probably wasn't the best idea to use that as the car electrical system leaves a lot to be desired in terms of clean regulated power. Either build yourself a power regulator or do what I did and get yourself decent power inverted, a cheap wallwart and a regulator to power the amp. I just build a little 12V regulator for my IPod and using a 15V wallwart going to the power inverter which is connected to the electrical system of the car. That way, I know I've got some serious protection which I hope will keep my IPod alive.

 

[coyote65]

thank u for the answer.

So are you saying that I cannot repair my cmoy?

Could you tell me (in easyier way) if I could connect my cmoy to the electrical system of the car and why?

 

[error401]

You could connect your CMOY to your car's electrical system, but it's probably a bad idea for a number of reasons. Car power is very unclean and you will likely get enough noise on the output of the amp to bother you, especially if you're going for audio fidelity here. Ignition noise on the lines is one problem, as is the noise created by the large diodes in the alternator. If you can live with that, you've still got to handle the large swings in output voltage. Finally, if you're trying to connect your CMOY to your car stereo you might run into grounding issues due to the virtual ground. If you want to try it though it should be reasonably safe, I'd just recommend you don't go anywhere near 'cranky' opamps as they're much more likely to oscillate with the amount of power supply noise you're going to have. Of course, you could build yourself a regulator to take care of most of the power supply issues.

If you connected the voltage with the wrong polarity, chances are good that you've fried the opamp. You might also need to replace the power supply caps as these are polar as well. Since that's the majority of the cost of the amp, it might be easier to just build a new one than try to repair your existing one, though if that's all you did to it (and it was working before), it shouldn't be difficult to fix. Just make sure you hook the lighter jack up properly. I believe the tip is V+, but I'm not positive. Measure the leads with a meter before you connect your amp. If you don't have a meter, you might want to place a power diode in front of the amp (1N4001, 1N4002 etc. would be appropriate) to protect it in case you do this again. You'll lose some voltage through it though so you may want to remove it once you determine the correct orientation.

FallenAngel: You might have some fun building a little boost converter followed by some filtering to power your amp. Something like the LM2585 seems appropriate. The switching freq. is a bit close to the audio range, but follow it by some hefty filtering (or even a full-fledged LM317A based linear reg) and it should be fine. Way more fun than using an off-the-shelf inverter

.

 

[FallenAngel]

To say the truth, the main reason I was using the inverter (on top of the obvious fact of having an extra 120V AC socket in the car) was because the circuit already has some serious voltage protection and a slow-start mechanism that keeps the voltage output steady until the full 12V-14V from the car kicks in. Without it, any DC-DC converter and regulator I've ever built would give unregulated power for at least a few seconds while the car turns on. Since it's a $200+ toy I'm connecting to it, I really did't want to take a chance of frying it if I forget to unplug it before turning the car on.

cayote65: Be careful when you're screwing around with the car electrical system, with the amount of amps of current that it has, it will seriously hurt if you short it with a finger or tool!