How can I get a custom built LED circuit pulse to the music?

[ozzlo]

Well I could put this in general hardware... but I figure you volt modders will be able to help me out a bit more as you probbably have some stronger eletronics background than other regular members.


Situation: I have an dell inspiron 9300 LAPTOP which I have allready built a Working LED circuit that has 9 LED's with a switch I put into the side of the chassis to turn them on or off. Now I want to figure out how to utilize sound or the voltage supplied by the speaker connector on the motherboard to make the LED's "pulse to the music". The laptop has a built in 1" subwoofer with the speaker rated at (i'm not positive but i think it said 5 watts 8 ohm).




Basically here is my circuit to help things out.

My power source is one 5v USB port with a max power output of 2.5 watts.

if you follow the +5v lead from the USB port there is a ON/OFF/ON switch and then a 20 ohm resistor. Then following that are 9 3v LED's in parallel and then there is a wire going to the common terminal of the USB port completing the circuit. The total current of the circuit is somewhere around 180-190 mA.


Possible solution I thought of: I have thought about strapping a microphone straight onto the subwoofer and using a transistor to amplify the signal but there isn't very much room (less than 1/4") and I don't know if a transistor can amplify that small of a signal. (I have a microphone that I put up to the sub[cranked to full blast] and with the voltmeter i was getting .000v out of it) I think it is some sort of powered microphone that only picks up stuff when plugged in though (i'm not really up to date on how microphones work but I figure it's just opposite of how a speaker works...


I have also thought about taping into the subwoofer power and using a relay or transistor to control the circuit that way but, I don't really have much experience with relays and I can only grasp and work with basic transistors plus I don't really want to take power away from the subwoofer.


restrictions: size is the largest restriction as there is only about 3/8" by 1" by 1" space to make this work.

I don't know what I should use or what I need... I only have a couple of vauge ideas... I can probbably get any extra information that will help out. I await to answer any questions you guys might have to help you help me.

I have lot's o experience with resistors (voltage divider circuits)
and some experience with capacators diodes and transistors
and limited experience with inductors

[SolidxSnake]

Get a sound activation model (like $4) for a CCFL setup, and set that outside somewhere, and wire that into the LED circuit.

[four4875]

i think he wants it to be internal. all i can think of would be to rectify one of the lines to the sub, then a capacitor and a switching transistor, that would turn the lights on and off based on the sub being hitting or not. you could do a fade kind of thing pretty easily i would think, but im not sure how that would do / what transistors you'd need to use. i think you could get away with small packaged ransistor and a diode and a cap, so the lights tont flash at whatever frequency the sub is hitting at.

[SolidxSnake]

you might be able to make a low-voltage relay, and than when the speakers get a signal, it'll throw the relay, and then light the LEDs.

:shrug: