Flashing light in time to the music?

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Hello, I am looking to make a SIMPLE circuit with adjustable sensitivity that operates a relay in time to the music... I would liek it to accept a line level signal if possible, and operate from 12volts and switch a 12volt relay... I really don't know where to start.. I tried searching the internet, but didn't really know where to begin.. Thanx for all the help. . :)
 
I put something like this together years ago. Going off of memory, it was nothing more than an op-amp in a high pass configuration (to eliminate DC), a second stage that provided a huge amount of gain, a diode at the output of that stage (not a schottky, too high of leakage), a capacitor to ground, a high value resistor parallel to the CAP that would set the turn off delay, and then the positive lead of the cap into the gate of a MOSFET which would turn on the relay.

Now, I just use one of the switched outputs of my AV receiver to control a relay that turns everything else on, but I am guessing you are turning on a sub or something remote.

If the above is too tough to follow, I can put a quick schematic together, but no guarentees it will be right the first time.

Alvaius
 
SkinnyBoy said:
yeah, I found colour organs, but they generally ran from the mains, and used triacs to switch the globes... I will search again however.. :)


You are correct in that, that's what most of the do, but there's nothing that says you can't adjust and use 12volts instead of 120volts. (Can't you just feed 12volts through the triac, and get that, its a maximum voltage, isn't it?) If you use the basics presented in those circuits, you should be able to scale them down a little and get what you want.

Why are you hooked on a relay? If what you're looking for is something along the lines of the color organ, the relay won't respond fast enough and will be constantly switching on and off. Or are you looking for some type of threshold device that'll kick on when music is played? (similar to a lot of subwoofer amps)
 
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