A Scale that detects weight based on capcitance changes
- How to use an oscilliscope to measure various things.
- What step response *really* is
- All about hi-pass and low-pass filters and how they work
This is a picture of the whole scale setup. I used the hello3 circuit with one modification and
built my own spring with capacitive plates. The modification was that I added a .5MOhm resistor on
PIN 6(PB1) to create some current and nto just a pulsing voltage.
The underside of the blue plate is an S shaped 'spring' with 2 copper plates (see image below). One plate is charged with
5 volts. The other leads to an Analog to Digital converter which reads the speed at which the voltage
increases. As the distance between the two plates decreases(weight is put on the scale) the charge time
gets shorter and the weight is detected.
Here are the files relevant to the scale: