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Discussion Starter #1
hey guys, i made a led circuit that is driven off the subwoofer output of my double din ddx514. for some reason the light circuit isnt working, however i tested the system before i installed it into the car and it was functioning. So ive isolated the problem to the ground wire, becuase the LEDs work in the other switch configurations so I know they are getting power.

it is either that the audio is unbalanced (signal isnt measured from ground?) or that the ground wire going to the chassis shouldnt be going to the chassis?
is there a specific audio ground circuit that I have to splice into? i cant figure out why the sound circuit isnt working, its really basic and i already tested it as working before I had put it into the car. during the test it wouldnt work because the audio wire did have a wire for ground, I changed the cable and it all worked (ground also was connected to negative side of battery). Now I am having the problem again, and am positive the problem is the ground (since the audio ground and chassis ground wires are connected).

Does anyone know if there is a specific ground for me to splice into to get it to work?

heres the circuit: (cept change the 9v to 12, and the led+resistor is combined and already rated for 12v)
 

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What is the purpose for this circuit? From what I can tell, it seems that you plug it into your sub outputs on your headunit and it lights up with the music? If I know what its supposed to do I might be able to help more.
 

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What is the purpose for this circuit? From what I can tell, it seems that you plug it into your sub outputs on your headunit and it lights up with the music? If I know what its supposed to do I might be able to help more.
yep! exactly. i tried it on my computer and it worked great. hooked up the power to the circuit in my car, and it no longer worked even though the audio was coming from my computer again. so yeah, its definitely the chassis ground. i just dont know why its the chassis ground or how it should be fixed
 

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If you have it wired into a speaker wire or RCA output, you only need to use the corresponding negative terminal/wire to ground it.
 

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Discussion Starter #5
If you have it wired into a speaker wire or RCA output, you only need to use the corresponding negative terminal/wire to ground it.
hmm i had a feeling of that. the circuit already works as is, with the ground connected to the audio ground and also the battery negative terminal, tested it before installation. But how can i accomplish that? the transistor utilizes the ground wire to finish continuity to the led circuit and what i am assuming is also establishing the audio ground as a reference voltage (?). the transistor needs to have a ground for the led circuit. can i just ignore the audio ground and maybe throw a capacitor in series with the mono audio to remove any dc bias and then rectify it?
 

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Way over my head, I only know the basics on wiring and circuit boards. Sorry I couldn't be more help
 

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Discussion Starter #8
yeah its a similar system, the difference is that it uses a microphone whereas im trying to directly sample the music
 
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