Today, we are going to be using 555 timers to create some musical instruments! We will be building a theremin, organ, and an Atari Punk Console. I used this activity in my classroom to celebrate graduating from discrete components to integrated circuits. This activity made a great segway into the rest of the course after covering the fundamentals of resistor-capacitor (RC) circuits and semiconductors. I had never seen students so frantically solving algebraic equations to compute the perfect capacitance values to tune their instruments to the correct frequencies before the performances. This activity is a lot of fun and teaches many aspects of circuit design. It also taught me the importance of adding volume knobs to circuits that make noise. You learn that very quickly in a room filled with a dozen screeching theremins!

This project requires a little bit of hardware knowledge, some knowledge of RC circuits, and some breadboarding. If you aren’t familiar with 555 timers, that’s fine! I will teach you everything you need to know about 555 timers in the first section.

Special thanks to Forest Mims who wrote some of the best and most accessible introductory books about electronics. His “Toy Organ” and “Stepped Tone Generator” are the basis for the Organ and Atari Punk Console. If you are interested in learning more about electronics, his book “Getting Started in Electronics” is a great place to start. It is very well-written and comes with 100 different circuits you can build!

Theremin:

1x 555 Timer
2x Photoresistors
1x 10 kOhm Resistor
1x 1 MOhm Resistor
1x 1 kOhm Potentiometer
2x 0.1 uF Electrolytic Capacitor
1x 100 uF Electrolytic Capacitor
8 Ohm Speaker (1-2 Watts) or Passive/Piezoelectric Buzzer
Some jumper wires
9V battery
9V battery clip

Organ:

1x 555 Timer
1x 10 kOhm Resistor
1x 100 kOhm Potentiometer
1x 1 kOhm Potentiometer
1x 0.1 uF Electrolytic Capacitor
1x 100 uF Electrolytic Capacitor
A whole mess of various ceramic capacitors ranging from 1 nF to 22 uF
8x (or more!) Tactile/Momentary Pushbuttons
8 Ohm Speaker (1-2 Watts) or Passive/Piezoelectric Buzzer
Some jumper wires
9V battery
9V battery clip

Atari Punk Console:

2x 555 Timer
1x 1 kOhm Resistor
2x 470 kOhm Resistor
1x 1 kOhm Resistor
3x 0.1 uF Electrolytic Capacitor
1x 1 uF Electrolytic Capacitor
1x 100 uF Electrolytic Capacitor
8 Ohm Speaker (1-2 Watts) or Passive/Piezoelectric Buzzer