How to Build a Theramin Using Household Items

Introduction

A theramin is an electronic musical instrument that is played without physical contact. Instead, the musician controls the pitch and volume by moving their hands in the space around two antennas. Theramins create an eerie, wavering sound that is often associated with science fiction films.

While commercial theramins can be expensive, it's possible to build a simple version at home using common household items. In this guide, I'll walk you through each step of constructing a DIY theramin using materials you likely already have around the house.

Gather Your Materials

The great thing about building a homemade theramin is that you don't need fancy electronic components. Here's what you'll need to gather before starting:

• Cardboard box or other non-conductive enclosure - This will form the body of the theramin. A cardboard box, plastic storage bin, or even an inverted terracotta flower pot could all work.

• 2 metal antennae - These can be made from wire coat hangers, aluminum foil wrapped around cardboard, or similar. You want them to be straight, about 6 inches long, and sturdy enough to stand upright.

• 1 555 timer integrated circuit- This is the only electronic component you'll need. You can remove one from a cheap electronics kit or even salvage it from a damaged device.

• 9V battery and holder - Supplies power to the circuit. You can also use four AA batteries in a holder instead.

• Assorted wire, resistors, capacitors, and an LED - See full parts list in the next section for details. These are scavenged from old electronics or bought inexpensively.

• Soldering iron and solder - To assemble the circuit.

• Hot glue gun - For attaching components inside the enclosure.

That's it! These basic parts are all you need to begin constructing your homemade theramin.

Required Components

While the list above covers the main categories of items you'll need, here is the full list of required electronic components and values:

• 555 timer chip - 1
• 9V battery - 1
• 9V battery holder - 1
• 10 kiloohm resistor - 2
• 100 kiloohm potentiometer - 1
• 0.01 microfarad capacitor - 1
• 0.1 microfarad capacitor - 1
• 680 picofarad capacitor - 1
• 10 microfarad electrolytic capacitor - 1
• Red LED - 1
• SPDT toggle switch - 1
• Wire - Various lengths
• Antennae - 2

Don't worry if you don't understand what each component does - I'll explain their purpose while going through the assembly steps. The key is gathering this assortment of basic electronic parts.

Constructing the Circuit

With your materials assembled, it's time to build the theramin circuit. We'll go step-by-step through each connection you need to make. Refer to the diagram below as a visual guide:

555 Timer and Decoupling Capacitors

First, insert the 555 timer chip into the center of your breadboard. Place the 0.01uF and 0.1uF capacitors directly next to each VCC pin of the 555. These are "decoupling capacitors" that help smooth the power supply.

Volume Control

Next, insert the 100k potentiometer near the top of the breadboard. Place one end of the potentiometer in the breadboard hole connected to pin 5 of the 555. The other end will go in a hole that's 5-6 holes away.

Run a wire from the wiper pin of the potentiometer to the positive voltage rail on the side of the breadboard. This pot will allow you to control the volume.

Oscillator Components

In the lower half of the breadboard, insert the 10 uF electrolytic capacitor with the positive leg in hole 27 and negative leg in 28.

Insert the 680pF ceramic disk capacitor into holes 25 and 26. Next insert the two 10k resistors into holes 23 and 24.

Finish up the oscillator portion by running wires to connect these components to pins 6 and 7 of the 555 timer.

Output Indicator

To add a simple visual output indicator, place the red LED in holes 19 and 20 along with the 330 ohm resistor in holes 18 and 19. Run a wire from hole 20 to the ground rail.

Power Wires

Use wire to connect the positive and negative voltage rails to your 9V battery holder. Add a power switch if desired.

That completes the theramin circuit! Be sure to double check that your wiring matches the diagram.

Constructing the Enclosure

Now that the electronics are complete, you need to add the antennae and build an enclosure:

• Glue the two metal antennae upright on opposite sides of your enclosure base

• Hot glue the circuit down flat inside the enclosure

• Drill a hole for power wires to pass through and add a power switch if you added one

• Carefully re-attach the enclosure lid once the glue has cooled

• Decorate the enclosure as desired - add knobs for controls, labels, paint or other decorations to make it look nice

Some tuning may be required to get the optimal distance and angle between the antennae. Experiment by adjusting their positioning while playing, until you achieve the smoothest sound.

Playing Your Homemade Theramin

Once assembled, here is how to use your DIY theramin:

• Turn on the power switch and make sure the LED lights up.

• Move one hand near the left antennae to control pitch - up and down to change notes.

• Move the other hand near the right antennae to change volume. Closer means louder.

• Use gentle motions and find the "sweet spot" distance for each antenna that gives you the best sound.

• Get creative! Try using different hand shapes and motions to warp the sound.

It will take practice, but you should be able to produce basic melodies. Enjoy creating eerie sci-fi soundtracks or funky beats with your new homemade theramin!

Troubleshooting Issues

If you don't get any sound, or the device isn't behaving properly, here are some troubleshooting tips:

• Check all solder connections and wiring compared to the diagram for errors. Re-solder any connections that look cracked or dirty.

• Ensure the battery/power supply is providing adequate voltage. Replace batteries if voltage is low.

• Adjust component values slightly (i.e. the capacitors) if tuning is off.

• Add shielding inside the enclosure to block interference.

• Reposition the antennae and adjust their angles/distances.

• Change the type of antennae if needed to optimize sound quality.

With persistence and trial-and-error, you should be able to get your homemade theramin working well. The process of tweaking and refinement is part of the fun of DIY electronics!

Closing Thoughts

Building a theramin using common household items is an enjoyable electronics project that produces impressive results. Following this guide, anyone can inexpensively construct a fully functioning instrument from scavenged parts with minimal tools.

Not only do you end up with a unique conversation piece, but you also learn a ton about audio circuits and the theramin itself. The finished product brings an otherworldly element into your home. For more musical hardware projects, electronics Kitty has many theramin tutorials and schematics to explore.

Now get creative modifying and improving your own theramin design! With further tweaking and refinement, you can produce truly alien and sci-fi sounds from homemade hardware.