About this project
Update: Rounds 1, 2, 3 and 4 are sold out! Deciding not to add additional rounds of kits in this campaign has been difficult, but we don't want to take on more than we can handle. We'd rather focus on ensuring that everyone who's already getting a kit from us will be satisfied. Add your email to our list to be notified when we make more kits available at our website, onetesla.com.
Update II: For backers who have bought bare boards, we'll have a "complete your kit" option on our website soon, which will ship by March. Also, don't forget to join the forum!
DIY Lightning: build your own musical Tesla coil!
oneTesla is a little Tesla coil that takes MIDI input and plays music using sparks. Its secondary coil stands only 10" tall, but it can produce lightning nearly 2 feet long. Check out the user manual (under continuous improvement until the Kickstarter campaign ends!).
With a Tesla coil, you can play with music-making plasma, experiment with wireless power transfer, dabble in power electronics, or just impress your friends with a spectacular lightning show. Now we're making it easy for you. All you need to assemble a oneTesla are good soldering skills and some common tools.
We've worked tirelessly over the past months to make a polished prototype that is reliable, inexpensive, compact, and easy to assemble. We've been working with suppliers to be ready to place a bulk order of specialized parts - so that you, the hobbyist, don't have to sink tens of hours (and potentially hundreds of dollars) into winding a few thousand feet of fine wire by hand, making custom enclosures, or printing your own circuit boards. Instead, you can focus on the fun stuff, like connecting the Tesla coil to a MIDI keyboard and playing your favorite songs, or making improvements to share with others (we're completely open-source)!
How does it make music?
Sound is a pressure wave, and different pitches are created by different frequencies of the pressure wave. Humans can hear between approximately 20Hz and 20kHz. The Tesla coil resonates at about 230kHz, a frequency that's much higher than human hearing. But we turn on and off the sparks (which are firing away at a high frequency) at the audio frequency we want to hear. So if we want an octave above middle C, then we turn on and off the pulses at 524Hz. Each spark creates a peak of a pressure wave, and our ears perceive this as hearing sound.
Let's get technical.
The Tesla coil is a resonant transformer - see the manual for an explanation of what this means. oneTesla consists of several major parts:
- The driver board powers the whole Tesla coil. Sitting inside the main chassis, you plug it into the wall with a power cable, as well as a DC power supply. It gets an optical signal from the interrupter, which tells the Tesla coil when to turn on and off.
- The interrupter board takes a MIDI input and outputs an optical signal. This fiber link is necessary to isolate the high voltage from your delicate music-making electronics. It has a microcontroller that converts the MIDI track into on-off pulses for the Tesla coil that make the sparks play music. Our interrupter is polyphonic - it can play 2 notes at once. The interrupter also has a knob that controls power.
- The primary coil. A few turns of thick wire on an acrylic form, this coil is directly connected to the main control board. The primary sits at the base of the secondary and excites it.
- The secondary coil is 1800 turns of fine wire on a long, thin form, which gives the Tesla coil its distinctive look.
- The topload is a toroid perched on top of the secondary coil, which forms a capacitor to ground. Together with the secondary coil, it forms a resonant circuit that can build up to extremely high voltages.
See the our website for some more photos of oneTesla in action.
- Primary: 6 turns of 14AWG wire, 3.5" OD acrylic former
- Secondary: 2.5x10" of 36AWG magnet wire.
- Tank capacitor: CDE 940C30S68K, 0.068μF@3000V
- Topload: 8"x2" metal toroid
- Resonant frequency: ~230kHz
- Inverter: half-bridge of FGA60N65SMD IGBT's running at 340V.
- Driver: Primary current feedback driver.
- Peak primary current: ~300A.
- Pulse-widths: adjustable from 0 to maximum pulsewidth. The maximum pulsewidth ranges from 50μs (at 1KHz) to 150μs (at 50Hz) with a maximum duty cycle of 5%.
- Maximum recorded spark length: 23".
We're completely open-source.
Without the support of the DIY community, we wouldn't be where we are now. We want to give back, so all of our work is licensed under the GNU GPL/FDL licenses. That means that you have full rights to reproduce and improve our designs, as long as you propagate the license.
Why do we need your help?
We want to bring Tesla coils to hobbyists who aren't necessarily experts in the field. We've sunk a lot of time and money into developing oneTesla. Many of the components we need, as well as custom-manufactured parts, are only affordable at a low price point if we order them in bulk. We need your help to get off the ground!
Who should build this kit?
This kit is an advanced project - one sloppy solder joint could leave you with a smoking board (and trust us, burning electronics aren't pleasant). You should have prior experience with building and troubleshooting electronic kits to reliably construct a oneTesla coil. It's conceivable that a beginner can get a oneTesla kit to work, but it is STRONGLY ADVISABLE to have access to an experienced mentor who can provide advice and help troubleshoot. If you're under 18, you should build this kit under the supervision of an adult.
While not strictly necessary, it's useful to have an oscilloscope for troubleshooting purposes. If you want to be even safer, invest in a Variac - a variable autotransformer that allows you to control the voltage input to the coil.
Risks and challenges
We've worked hard to make a reliable and user-friendly design. But Tesla coils are advanced projects, which still require skill to assemble correctly. We're most concerned about helping people with the problems they may encounter.
To this end, we already have a detailed user manual, which provides a thorough explanation of Tesla coil operation, safety procedures, step-by-step instructions, and lots of pictures. We also plan to launch a forum on our website, where users can share the problems they run into, and we can provide support accessible to everybody.Learn about accountability on Kickstarter
You should be experienced in soldering and electronics troubleshooting to build this kit, or have access to an experienced mentor who can check your work and help you. While we attempt to give complete and thorough instructions, there's no substitute for prior experience, and this is an advanced kit to assemble.
While not strictly necessary, it's useful to have and oscilloscope for troubleshooting purposes. If you want to be even safer, invest in a Variac - a variable autotransformer that allows you to control the voltage input to the coil.
Yes, this is in the description above but we're repeating it here in case you overlooked it.
Heeding safety warnings, understanding and following the instructions, practicing good workmanship, and using a healthy dose of common sense can mitigate the safety hazards. But please understand that this is not a project for everyone. Below is a list of the safety concerns.
1) High voltage RF of the output
oneTesla's topload reaches around a quarter million volts at ~230kHz. Never come into contact with the arcs. At best, you will get a nasty burn; at worst, you’ll get a potentially life-threatening shock. You should be several meters away from the coil when it is running.
2) High voltage DC on the control board
When energized, the control board has 340VDC on it at currents up to hundreds of amperes peak. It only takes 10mA across your heart to kill you. Never plug in the board if it's not in the chassis, and wait 5 minutes after you unplug the board for the capacitors to discharge before servicing the board.
3) Ozone buildup
Ionized air creates ozone, which is an irritant gas. Only use the Tesla coil in a well-ventilated area.
4) EMI hazard
Radiated energy from the Tesla coil can interfere with nearby electronics. KEEP AWAY FROM THE TESLA COIL IF YOU HAVE A PACEMAKER OR OTHER ELECTRONIC MEDICAL DEVICE. It's common for the Tesla coil to interfere with capacitive touch sensors nearby, which includes laptop touch pads and smartphone screens.
5) Ear protection recommended
Although it might not be apparent from the videos, the Tesla coil is LOUD! Wear ear protection if you're in an enclosed space where sound reverberates. We include ear plugs in the kit.
You need a good soldering iron (you're making your life miserable with an iron that costs under $40, so don't even bother). You need common hand tools: a screwdriver, wire cutters, diagonal cutters, needlenose pliers, and a crimp tool (or large pliers). You need a glue gun or superglue. You should budget at least a full day for construction. An oscilloscope is very helpful, as is a Variac.
You can play a pre-recorded MIDI file from a computer using the USB-to-MIDI adapter that we include in the kit, or you can use a MIDI instrument such as a keyboard. The interrupter only reads the first track of the MIDI file, and can only play a maximum two notes at once.
- Tesla coil driver printed circuit board, and MIDI interrupter printed circuit board.
- All necessary electronic components for assembling the two boards.
- Pre-wound 2.5" O.D. x 10" secondary coil.
- Primary former, primary support clips, and primary wire.
- Foam toroid and aluminum tape (we're still looking into spun toroids).
- Laser cut acrylic chassis for the driver board and interrupter.
- All necessary hardware for putting everything together.
- 19V power adapter, AC power cord, and 9V battery to power everything.
- USB to MIDI adapter.
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