Mirko Pavleski Turns an Old Microwave Oven Into a Pocket-Friendly Spark-Shooting Tesla Coil
Built using as many parts from a scrapped microwave as possible, this 20"-spark-length coil offers a pocket-friendly entry into the hobby.
Maker Mirko Pavleski has penned a guide to building a Tesla coil on the cheap, by swapping out the usual neon sign transformer high-voltage power supply for transformers ripped from scrap microwave ovens — delivering a bargain-basement device nevertheless capable of spark lengths over 20".
"Tesla coils are known for their ability to generate visually impressive electrical arcs or sparks, making them popular for educational demonstrations, entertainment, and as a hobbyist project. However, more 'exotic' parts are required for its construction, among which the HV [High Voltage] Transformer is the most difficult to obtain," Pavleski explains. "An old Neon Sign Transformer is often used, but they are difficult to locate in many countries. Likewise, new NSTs are prohibitively expensive for the hobbyist."
Finding a scrapped neon sign with a working transformer may be a challenge, but there's another source of high-voltage transformers: old microwave ovens, failed in a way that leaves the transformer intact. The only problem: the secondary voltage of these transformers is lower than is required to build a spark-shooting Tesla coil, which given they were only designed to make sure your dinner is hot is fair enough.
Pavleski's solution: doubling-up on the microwave transformers and adding a circuit to multiply the resulting voltage. "For the sake of economy," the maker explains, "I decided to use as many parts as possible from an old microwave oven. In this case, these are transformers, capacitors, and diodes. The primary windings are in parallel connection, and through a suitable fuse are connected to the mains supply. The secondary windings are in series to produce twice the voltage."
The resulting device, despite being made primarily from parts salvaged from scrap, delivers impressive 20" sparks from its connected coil — something Pavleski believes could be improved further with additional tuning.
Pavleski's write-up, including a schematic, is available on Hackster; the maker advises that only those familiar with high voltage safety attempt to build their own, as "direct current above 60V may be lethal, even when the AC supply has been disconnected due to the stored energy in the capacitors."