Using Microphone/Speaker Input to control lights

Thread Starter


Joined Jan 31, 2008
Hey everyone, I saw an article about a year ago where someone used a microphone (or a speaker posing as a microphone) to control a set of christmas lights.

Unfortunately, I can't seem to find this article again. All I can find are the ones where people connect a relay to the amplifier of a computer speaker. This isn't what I want. I'm after something that will pick up any sound (especially from my piano) and the lights will react to this sound.

I understand the basic concepts... microphone/speaker cables go to amplifier circuit, amplifier circuit controls a relay that is connected to a set of christmas lights.

I've been fooling around using a speaker scratched from a greeting card, and am trying to use this speaker as a microphone. I've hooked this speaker up to a series of 3 NPN transistors, which then control one LED. Unfortunately, I can't seem to get the vibrations of the speaker (including me literally moving the diaphragm up and down) to have much/any effect on the LED.

Any help?

Thanks much!