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Strobe Light + Beat Detector

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Hello everyone!

I'm modifying a strobe light trigger, in orden to fire it according to a music input. I've made some work, but I'm stuck on the 4th point.

1) The strobe light is just a cheap 12V chinese model, nothing interesting about that.

2) The lamp's trigger will be wired in series with a TRIAC, driven via optocoupler by the circuit.

3) Next part was the bandpass filter, to allow only low frecuencies to trigger the circuit. I've found a schematic (attached).

4) Now the bad part. I don't know a decent way to trigger the strober only when Low Frecuency signal reaches a determined Threshold (loudness).

I recurred to my old friend LM3915, using only one of its LED outputs (# 5). But is a waste of machine, I guess there is a better way!

On google I've found a microcontroller solution, but I have zero experience with them.

Is the solution some kind of comparator?


Active Member
Unfortunetly, I had no luck with the color organ circuit. Instead of working as a low pass filter, the circuit acts as a volume control. The capacitor just removes some of the low frecuencies, the opposite of the desired effect.

I guess the correct filter should include a coil, and a capacitor. http://www.tpub.com/content/neets/14181/css/14181_50.htm

All the circuits that I have found are active filters, or use IC's amplifiers (and the ic's require positive and negative voltage supplies). Maybe that's a requeriment for good quality audio, but my requeriment is much more simpler.

Any suggestion would be very, very appreciated
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