Building a miniature Tesla coil that can fit in your pocket is a fun electronics project that allows you to experience high voltage electricity on a small scale. With some basic electronic components, wire, and tools, I was able to construct my own pocket-sized Tesla coil that can wirelessly power small neon bulbs.

What is a Tesla Coil?

A Tesla coil is an electrical resonance transformer designed by the inventor Nikola Tesla in 1891. It is used to produce high voltage, low current, high frequency alternating current electricity.

The two main components of a Tesla coil are:

The alternating current in the secondary coil charges the terminal at the top to extremely high voltages of ~100,000 volts or more. This voltage ionizes surrounding air molecules causing the dramatic corona discharge and arcing that Tesla coils are known for.

How a Miniature Pocket Tesla Coil Works

A miniature pocket Tesla coil works on the same principle as a full size Tesla coil but is much smaller and designed to run on lower voltages.

The key components I used to build my pocket Tesla coil are:

The oscillator circuit converts the 12V DC into pulses of high frequency AC electricity at ~500 kHz. This oscillating current is fed into the drive coil which induces a magnetic field in the resonance coil.

At its resonant frequency, the voltage in the resonance coil builds up through each cycle of the AC power to around 5-10kV. This ionizes the air at the topload terminal creating corona discharges and arcs.

Constructing the Coils

The most important step in constructing a miniature Tesla coil is building proper primary and secondary coils with the right number of turns and diameter.

To make the primary drive coil:

To make the secondary resonance coil:

The resonance coil should have an inductance of ~1mH. I measured the inductance with a multimeter to fine tune the number of turns.

Constructing the Circuit

The oscillator circuit provides the high voltage AC current that drives the Tesla coil. I built mine around a NE555 timer chip:

Circuit schematic

To build the circuit:

Tune the frequency with the variable resistor to find the resonance point of the secondary coil, indicated by maximum brightness of discharge. Around 500kHz works well.

Adding a Topload Terminal

The topload shapes and enhances the electrical discharge at the terminal of the secondary coil.

Testing it Out

Once assembled, connect your 12V power source and enjoy the plasma light show!

With some careful winding, tuning, and tweaking, your pocket Tesla coil will be electrifying! Just be very cautious, as the high voltages involved can be dangerous.

Building a DIY Tesla coil that fits in your pocket is an extremely fun electronics project that lets you experience high voltage electricity firsthand. The construction process teaches valuable skills and the end result is a conversation piece that impresses any crowd. Just be sure to follow proper safety precautions when operating your handheld high voltage generator!