How to Build Your Own Tesla Coil

Anyone can build their own Tesla Coil, and now it’s easier than ever thanks to oneTesla co-founders Bayley Wang and Heidi Baumgartner.

The MIT students came together at the MIT hackerspace, MITERS, with access to machine tools, electrical equipment, and most importantly, a community of people with similar interests.

“Tesla coils have been our hobby for a while. We developed our first product, the first version of the oneTesla kit, more or less for fun, and put it on Kickstarter a year and a half ago to see what would happen,” explains Baumgartner. To the pair’s surprise, the kit raised nearly $170,000 in a week, but they decided to put the brakes on the campaign as they weren’t sure if they could handle more demand.

Since then, they have received feedback on how to improve product, including request for a smaller, simpler kit. “We also thought for a long time about what would make the ideal small Tesla coil, as well as how to improve the mechanical design of our first kit,” adds Baumgartner. “That’s how tinyTesla and oneTeslaTS were born.”

Currently seeking funding on Kickstarter, the tinyTesla, and oneTeslaTS have already raised more than their predecessor, with more than $258,000 raised, and exactly one week left in the campaign.

Tesla coils are a type of resonant transformer that produce extremely high voltages when driven by a high-frequency AC. The team at oneTesla generates the AC needed to drive the coil using an insulated-gate bipolar transistor (IGBT) inverter running off of 340 VDC.

“In order to play music, a microcontroller processes MIDI input and converts it to pulses that turn the entire coil on and off at audio frequency. What you are hearing is not the resonant frequency of the coil itself (which is around 300 KHz and therefore inaudible) but rather these “gate pulses” that are produced at audible frequencies,” explains Wang.

The tinyTesla design fits the coil into the smallest space possible, which also reduces the amount of material needed, helping reduce cost.

“We figured, ‘why not put the primary and secondary coils on the same former, and also put the driver in the base, eliminating the need for a separate chassis?’ Using a clear acrylic tube, the circuit board that the user assembled would be visible,” explains Wang. “It worked out quite well and resulted in a small Tesla coil that you can hold in your hand.”

The team also wanted to make it easier to connect the Tesla coil. In its current form, users can control the tinyTesla directly over a USB from their computer. However, the most innovative parts of the oneTeslaTS are in the mechanical design.

“Inspired by a modification of our original coil with a custom flat primary coil wound out of copper tubing, we decided to try out an etched primary coil on a board,” says Wang. “It worked great, and the board also doubles as a structural component, because you mount the secondary coil onto it. To cut down the number of suppliers we needed, and to keep a consistent sleek black look, we decided to make the sides of the chassis out of FR-4, so that it can be produced by the same place that makes our circuit boards.”

The PCB designs were completed in CadSoft Eagle and the mechanical design was done in Solidworks. For prototyping, the circuit boards were manufactured in China, and acrylic components were made mostly in-house. The team used their existing metalworking partners for the machined metal parts.

“There’s no way to avoid the fact that hardware takes time, particularly when you’re making parts for which you can’t use rapid prototyping techniques in-house,” explains Wang. “Waiting for parts was hands-down the most frustrating aspect of the development cycle.”

In terms of engineering, the most difficult challenge was balancing performance and reliability. “The more you push your IGBTs the better the performance of the coil, but reliability suffers,” Wang adds. “We chose what we think are good operating points.”

In the upcoming months the team is focusing fulfilling rewards smoothly, and will work on a Youtube tutorial series surrounding electronics. “This is something that we wish was out there already to help out beginners. In the future, we hope to distribute our coils in shops that already sell science and engineering kits,” says Baumgartner.

With increasing interest in DIY kits, the team is happy to see the hobby electrics community grow, and to reinforce that there is no better way to learn than by doing. “We’re concerned that there are only so many people who have the inclination to build their own DIY projects, but we hope that with outreach, we can make this number larger,” adds Baumgartner.

“We hope to excite students of all ages about electronics with fun, rewarding project. If you can solder, you can build tinyTesla.”