“When I first heard there was a microchip manufacturer called Potato Semiconductor Corporation I immediately knew I had to try to put an electronic circuit on a potato chip, to make my own ‘microchip’, or ‘macrochip’, so-to-speak. And so I did. You can see it in action in a video below.
For the circuit I wanted something fun that would make some sense. Drawing on my experience with my music player projects, I came up with the idea of having a 555 timer circuit that would play a sound and use a photoresistor to vary the frequency of the sound. The photoresistor is a resistor, as the name implies, but its resistance depends on the amount of light it receives, hence the ‘photo’ in the name. With the 555 timer circuit, the resistance between pins 6 and 7 is part of what determines the output frequency and therefore the sound. So the photoresistor went there.
The result is that you can put the macrochip in the bottom of a bag of chips and the sound would be one frequency (it ended up being a ticking sound, as if there was a bomb in the bag). Then as you remove chips from the bag, the photoresistor gets more and more light and so the frequency changes, until finally you dump it out of the bag and by then the sound is a squeal.
I made sure to get plain chips, non-salted, since salt or other ingredients could make it electrically conductive. Once I found a big enough chip, I tested the resistance with a meter to make sure it was infinite resistance. To make the chip solid enough, I coated it in 2 coats of clear epoxy resin and waited a few days to make sure it was stiff.”