Assignment I:
Variable Resistance Piano
The first assignment was to build a fancy variable electronic resistor. I built a table-sized piano made of a wet cardboard. The resistance increases with the distance between the cable connection. The internal structure of the cardboard affect on the current.
© Darsha Hewitt
The current flows through a basic 555 timer circuit - creating square wave oscillations which can be played on a speaker. By changing the distance between the connection on the cardboard you can change the resistance and the pitch of the tone.
Assignment II:
The Boiling Water Indicator
The second assignment was to build a fancy electronic switch. I built a construction of a basic 555 timer circuit (creating a square wave oscillation connected to a speaker) which power on/off is triggered by a connection of two contacts. I put the contacts into a water filled glass tube which was set over a flame. Immediately after the water is boiling the expanded water volume let current pass to the circuit.
Final Assignment:
The LED Pulse Sensor