How to Build a DIY Theremin Using Only Hardware Store Supplies

Building your own theremin using supplies from the hardware store is a fun electronics project that allows you to create your own musical instrument! Here is a step-by-step guide on how I built my own DIY theremin using only parts from the local hardware store.

What is a Theremin?

A theremin is an electronic musical instrument that is played without physical contact. It consists of two antennas, one that controls pitch and one that controls volume. By moving your hands in the electromagnetic fields around the antennas, you can produce musical tones and effects.

Theremins were invented in 1919 by Russian physicist Leon Theremin and were one of the first electronic musical instruments. Their eerie, wavering sound made them a staple of movie soundtracks in the mid-20th century. Theremins are now enjoyed by electronic music hobbyists around the world.

Shopping List of Parts and Supplies

Building a basic DIY theremin requires a few key components that can all be purchased affordably at most hardware stores:

• Variable capacitor - This component controls pitch. Get one with a range of about 350-500 pF.

• Metal antenna - This will be the pitch antenna. A 1-2ft length of metal rod, tubing, or wire will work well.

• Loop antenna - For volume control. Use stiff wire or tubing bent into a 5-6 inch loop.

• Resistors - Two 10M ohm resistors, one 1M ohm resistor, and one 100k ohm resistor.

• Transistors - One 2N3904 NPN transistor and one 2N3906 PNP transistor.

• Battery snap connector - For attaching a 9V battery.

• Wire - Stranded hookup wire, multiple colors.

• Project enclosure - A plastic box to mount the components inside.

• Volume knob - Standard guitar/equipment knob.

• Headphones - Theremin has no amplified sound, so headphones are needed.

Tools Needed

To assemble the theremin you will need the following tools:

• Soldering iron and solder
• Drill with small bits
• Wire cutters/strippers
• Screwdriver
• Ruler and pencil

A multimeter can also help troubleshoot if needed.

Step-by-Step Building Instructions

Follow these steps to assemble your DIY theremin:

1. Drill enclosure and mount parts

Drill holes in the plastic enclosure to mount the variable capacitor, volume knob, antenna connectors, and headphone jack. Attach these components in place.

2. Build the pitch control circuit

The variable capacitor and antenna form an LC oscillator that creates an audio tone that changes with hand proximity.

• Solder a 10M ohm resistor from capacitor positive to the collector of the 2N3904 transistor.
• Solder the 1M ohm resistor from the transistor's emitter to its base.
• Connect the emitter to ground.
• Solder a wire from the transistor collector to one side of the capacitor.
• Connect the other capacitor wire to +9V.
• Install an antenna wire and connect it to the capacitor's connector.

3. Build the volume control circuit

The loop antenna and 2N3906 transistor form a simple variable resistor circuit to control volume.

• Connect one end of the loop antenna to +9V.
• Connect the other end to the transistor's collector.
• Connect a 10M ohm resistor from the collector to the base.
• Connect the emitter to ground through the 100k ohm resistor.

4. Join the circuits

• Connect the volume circuit's transistor collector to the pitch circuit's transistor base.
• Install a wire as the common ground.
• Install the battery connector with red wire to +9V and black wire to ground.

5. Install controls and connectors

• Drill holes for headphone jack and volume knob.
• Solder headphone jack tip connector to the pitch control transistor collector.
• Connect volume knob to the volume control transistor collector.
• Connect all grounds to the black battery wire.

Playing Your DIY Theremin

After assembling the theremin, connect a 9V battery and headphones. Bring your hand near the pitch antenna to produce tones. Move closer or farther away to change the pitch. Move your other hand near the loop antenna to control volume. With practice, you'll be able to play full melodies on your homemade theremin!

The basic theremin can be expanded by adding a third antenna for vibrato, connecting multiple pitch antennas to play harmonies, building a theremin into an interesting object or sculpture, and more. Get creative!

Building a theremin is a great way to learn about analog oscillators, variable capacitors, simple amplifiers, and more. Troubleshoot any issues with a multimeter and adjust components as needed. And most importantly, have fun playing your unique musical creation!