Rickharris
Senior Member
Instructable seem like it would work.
Simple pressure sensor
- Thread starter Rickharris
- Start date
I've built a few of those, and they seem to have a problem with repeatability.
I had better luck with a slightly different version. Instead of measuring resistance of the foam, you can measure the capacitance of a home-made capacitor made of a piece ordinary paper (the cheaper the better) sandwiched between 2 pieces of copper clad circuit board. In the pictures below, the sensor is held together with electrical tape and has a silicone stick-on bumper as a button.
A piece of thin rubber might also work as the dielectric, but it has to be really thin, and I couldn't find any.
The copper clad is about an inch square in the photos.
Repeatability is good. I can easily measure how many coins are stacked on the sensor. I even put the setup away for a couple years and was able to get the same reading.
exactly how you read the capacitance depends on the processor you use. I originally used RCTIME on and old Basic Stamp. When I migrated to the Picaxe, I constructed a simple Astable oscillating circuit using a 555 timer and measured pulse rate.
I eventually used the sensor on a robot to tell when it had its foot down.
I do like the Plastidip idea, though.
I had better luck with a slightly different version. Instead of measuring resistance of the foam, you can measure the capacitance of a home-made capacitor made of a piece ordinary paper (the cheaper the better) sandwiched between 2 pieces of copper clad circuit board. In the pictures below, the sensor is held together with electrical tape and has a silicone stick-on bumper as a button.
A piece of thin rubber might also work as the dielectric, but it has to be really thin, and I couldn't find any.
The copper clad is about an inch square in the photos.
Repeatability is good. I can easily measure how many coins are stacked on the sensor. I even put the setup away for a couple years and was able to get the same reading.
exactly how you read the capacitance depends on the processor you use. I originally used RCTIME on and old Basic Stamp. When I migrated to the Picaxe, I constructed a simple Astable oscillating circuit using a 555 timer and measured pulse rate.
I eventually used the sensor on a robot to tell when it had its foot down.
I do like the Plastidip idea, though.
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