Adding audio reactivity to bends?


I’ve been trying my hand at video circuit bending recently, and learned a lot in a fairly short amount of time. I’m not particularly well versed in electronics, but I have done a pile of modifications and builds over the years - mostly Game Boys (before there were nice easy kits available!) - but also other things like audio circuits blah blah.

Anyway, I’ve had some success with a few different devices now, and I’m looking to add in some audio reactivity to my future bends, but I’m not really sure how to go about that in relation to video particularly. I have some vague understanding of using transistors, but not enough to just dive in, and I come to you… the experts… with my cap in hand for any advice you can give, as there aren’t a whole lot of resources I can find on this topic.

Thank you in advance!


If the thing you’re bending has noticeably different behavior through a resistor, then you can always try a vactrol (LED + photoresistor)! The bendee will just see the change in resistance, and bender side can be as simple as either an audio level, or maybe an opamp to tweak levels a bit. The resistor side of the vactrol could be a direct bend, or maybe it’s to affect resistance in another part of a circuit. I think some of the Archer Video Enhancer mods can use a vactrol?


Thanks a lot. This sets me on the right path!

Essentially I would just connect up the audio input directly to the LED in that instance, which would mean it will light up or not depending on the signal… then the photo resistor would be connected between the parts of the circuit I want to bend, meaning that when the LED lights up, it will affect the bend? That’s genius. :slight_smile: I guess it would probably require a switch if the resistance wasn’t enough on the bend in the first place.

Let me know if I’ve misunderstood anything, but if not… I’m going to try this out. I appreciate it :slight_smile:

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Just noting I tried this out today and got it to work. Thanks a lot for your help :slight_smile: I need to experiment with both the LEDs used (for the colour range and brightness), as well as the type of photosensitive resistor, as I just used some unknown ones I had lying around. I’m hoping to get a bit more of a range on them, so that’ll be fun to try. Can’t wait to make a whole pile of ridiculous bends that I can control via my modular!

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I implemented the audio reactivity into my latest project. It’s the second successful bend I’ve done, and it was mostly an experiment to see how much I could find/cram in without blowing the damn thing up (again). There’s still a bunch of room in there, but I’ve kind of hit a natural end point.

I got a bunch of light based resistors (GL5506) that are more sensitive than the other ones I had, which worked better. I’m using ultra bright clear white LEDs, and they take a fair whack of voltage to light up (straight out my modular), so the more sensitive LDRs meant that I could tone that down a bit. I need to experiment some more to find the ideal combination.

Thanks for the help!