Assignment 1: variable resistance and conductivity

material: 555 timer, capacator, resistor, LEDLight-emitting diode, speaker and different conductive material

Current flows through the circuit, 555 timer in astable mode and the attached conductive material, which creates square wave oscillations that are output on a speaker.


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 555 astable 2a.jpg

Assignment 2: momentary switch

555 timer, 2 switches, relay, 2 motors, trash


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 current flows and the motors run. The second momentary switch works the same way, but is connected to a DPDT-relay. When metal is touching metal the polarity gets reversed which changes the direction of the attached motors.

Final assignment: Morgenflöte

555 timers, photocells, capactors, resistors, speaker, cardboard tubes

The "Morgenflöte/morning pipe" is a light depended instrument, which is best played in the morning...


Morgenfloete summary .jpg


It uses 2 or more photocells implemented in the cardboard tubes attached to 2 or more 555 timers in astable mode on a "burning circuit"(it´s getting hot).

Morgenfloete circuit.jpg