Potato chip macrochip with 555 timer circuit

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.

Potato chip macrochip with 555 timer circuit.
Potato chip macrochip with 555 timer circuit.
Chips and the potato chip macrpchip.
Bowl of chips and the potato chip macrpchip.

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.

Photoresistor.
A photoresistor or photocell.
The photoresistor on the potato chip.
The photoresistor on the potato chip.
The 555 timer circuit with the photoresistor.
The 555 timer circuit with the photoresistor and piezoelectric speaker.

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.

Plain chips.
Bag of plain chips.
Measuring the chip resistance.
Measuring the chip resistance.
Putting epoxy.
Putting epoxy on the potato chip.

One notable component is the battery. I needed around 4 or 5 volts for the circuit but I needed the batteries to be small and lightweight. For my previous laser communicator project I'd already come up with a way to take apart a pet toy laser from a dollar store and modify the case to use as a battery case. It contained 3 1.5 volt coin cell batteries connected in series for 4.5 volts and so it was perfect. Below is how I did it.

Inside the case is a spring, which I removed and soldered to a wire. I then cut a plastic disk with a hole in it and hot glued the wire into that hole.

A cut pet toy laser case.
A cut pet toy laser case.
Spring soldered to a wire.
Spring from the laser soldered to a wire.
Hot glued to a plastic disk.
The spring and wire hot glued to a plastic disk.

This was then hot glued to the end of the case.

I also needed an on-off switch, and so I soldered a thick wire to the endcap for the case. The endcap has a non-conductive coating on it so use acid (flux) when soldering to make sure to penetrate the coating. A copper tube from a hobby store fits snuggly over that thick wire, basically making a plug.

You can see the finished result below.

Hot gluing to the case.
Hot gluing the plastic disk to the case.
The thick wire on the endcap and the copper tube.
The thick wire soldered onto the endcap and the copper tube.
The finished battery case.
The finished battery case.

The chip was solid enough to drill holes for mounting components. The first thing I attached were some wires for holding the battery case in place.

Drilling a hole in the chip.
Drilling a hole in the chip.
Wires for holding the battery case.
Wires for holding the battery case on the potato chip.
The battery case in place.
The battery case in place on the potato chip.

The speaker was also an interesting component. For that I use a piezoelectric speaker taken from a microwave oven. This is the same thing I did for making an earphone for a crystal radio.

Warning: Accessing the area where there are electronics in a microwave oven can be dangerous. There is a high voltage capacitor there that needs to be safely discharged before touching anything.
Piezoelectric speaker in a microwave oven.
The location of the piezoelectric speaker in a microwave oven.
Closer look at the speaker on its circuit board.
Closer look at the speaker on its circuit board in the microwave oven.
The piezoelectric speaker.
The piezoelectric speaker.

The top and bottom views of the finished result are below. You can test it by using your finger to block the light going to the photo resistor. Different amounts of light give different sound frequencies.

The potato chip macrochip circuit - top view...
The 555 timer circuit on the potato chip - top view.
... and bottom view.
The 555 timer circuit on the potato chip - bottom view.
Modifying the sound using a finger over the photoresistor.
Modifying the sound using a finger over the photoresistor.

Video - Potato chip circuit/macrochip with 555 timer circuit

The following short video shows the making of it as well as demonstrating it in use, controlling the sound using a hand and with a bag of chips.

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