I had 2 electronic tea candles and I remembered reading something about listening to the output of a flickering tea candle (probably here). The tea candles consisted of a plastic housing with a compartment for 1 button cell, a on/off switch, a small circuit board with a LED and a diffuse plastic flame shape. So I connected a computer speaker to one of the LEDs and to my surprise it played "happy birthday!"

The circuit board only had a black blob and 3 connections (+,-,output) so I couldn't really bent anything but with a potentiometer in series with the power I could change the pitch. Since the housing was very small I put in a LDR and it works great. I also put in a LED as a power indication so I don't leave it on accidentally and drain the batteries.

With the other candle I tried hooking it up to a solar panel and that also works great (I'm definitely gonna try it with more circuits). I connected a on/off switch and push button in series with the power and put it in a small plastic case which I glued to the back of the solar panel.

schematic: N.A.
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