Combination of IR transmitter, bargraph and slider causes periodic on/off

My 8-year old son Ethan found an interesting combination that causes the AC switch to turn on and off periodically by itself. No timeout/arduino bit is used, just IR transmitter, bargraph and slider (in that order). I could not explain to him what is happening. I would appreciate if someone can help explain what is going on. He posted a video of his discovery at

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I’m guessing, but perhaps the array of op-amps on the bargraph bit sets up a harmonic oscillation when subjected to a particular current load, which is coincidentally provided by the slide dimmer. This oscillation is transferred to the IR transmitter and causes it to send out spurious signals.

Of course, that’s just a guess, but if I get a chance this week, I will set up this circuit: p3 USB power -> button -> proto module -> bargraph -> slide dimmer. Then, I’ll put an oscilloscope on the proto to see if there is anything going backward that might be responsible.

It’s a cool mystery - thanks @dany and Ethan!