hello need some help please

Discussion in 'The Projects Forum' started by ET3 Malone, Dec 8, 2009.

  1. ET3 Malone

    Thread Starter New Member

    Dec 7, 2009
    Hello to all. I am an electronics technician in the USN so i somewhat know what i am doing however i am having a little trouble with a circuit design and was hoping to find help.

    What i am shooting for is i have 6 (10-12) led ribbons that i have installed into my car. What i want is to have them beat to my music. My original idea was to hook a microphone through a transformer to bias a transistor then just hook up a 12 volt source from emitter to collector through the led. Haven't actually tried it yet so far I have been using a java circuit sim and it seems ok i am just wandering what the math would be on the transformer and power to run all the leds off of one sensor circuit. thanks in advance for the help.
  2. Audioguru


    Dec 20, 2007
    What is the transformer for?
    An electret mic can be amplified by an opamp or a transistor. A lowpass filter selects low frequency "beat" signals and rejects higher frequencies. It drives a peak detector circuit so that the peaks of sounds are stretched long enough to be seen. The peak detector drives a transistor or a Mosfet that turns on the LEDs.
  3. ET3 Malone

    Thread Starter New Member

    Dec 7, 2009
    sorry for not posting i lost my own thread.... thank you for the help. My original idea was i believe incorrect thus the trouble i have been having. I was thinking that since you can use a transformer to step up the voltage at a loss of amperage that i could just use a 1:2 transformer to up the voltage from the jack pluged into an ipod to a usable voltage to trigger the base of the transistor alowing 9 volts from emitter to collector in series with 3 leds. i got a more simple circuit to work i used a tip31 from radioshack 9 volt battery and a cut off plug pluged into my ipod. the thing i get now is it works perfect if i just plug it in...it beats to the music like it should but if i use a y jack in the ipod so i can plug in headphones or speakers and the lights it doesn't light anymore. thank you again for the ideas i am gonna continue working on it and see what i can come up with.
  4. Wendy


    Mar 24, 2008
    Don't know if this will work, never having built it, but I give it good odds. You will need to amplify the signal somewhat, and replace the U1B oscillator with your audio source.


    The signal going into U2C will need to be centered on 6VDC, with a 6VPP signal, based on a 12V car system.