sound activated relay?

I'm building a (non-PC) project, and I need a device that will close a circuit whenever the sound level reaches a certain intensity, and immediately close it when sound returns. This will be used to pulse a light to the beat of music, so it must be adjustable. Where could I find such a thing, or how might I go about building one?

right now, I'm thinking get a normal mic, and hook it up to a mosfet to amp it a bit. Then feed this thru a pot (sensitivity adjust) and into a solid state relay. The relay would then activate the circuit. Might this work?

[MeltMan]

http://www.epanorama.net/links/audio...s.html#measure

Might help, I'll keep looking... You could just use a vu-meter's top led to run a transistor then relay then light... and you would get the added effect of little lights that dance up to the top (being the big light)

or you could make one hella big light vu meter

[MeltMan]

http://www.epanorama.net/links/lights.html#soundlight

This might be better for what you want to do...

I love epanorama.net... you need a circuit? you got a circuit.