Introduction to Electronics
Assignment 1: variable resistance and conductivity
555 timer in astable mode with speaker and different conductive materials
Current flows through the 555 timer circuit and the attached conductive material, which creates square wave oscillations that are output on a speaker.
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By changing conductive material(water, metal..), you change the resistance and the pitch of the tone.
schematic for 555 timer in astable mode with speaker and different conductive materials
Assignment 2: momentary switch
switch, relay, motors 555 timer, 2 switches, relay, 2 motors, trash
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The first momentary switch is connected to the power supply of the circuit. By pushing the cardboard-button, the inside alu foil is touching alu foil and closes the circuit,the motors are on/off.
The second momentary switch works the same way, but is connected to a relay. When metal touches metal the polarity changes and the direction of the attached motors also changes.