Electronic – Building a Tesla Coil

high voltage

I want to have a go at building a Tesla Coil.

Has anybody here tried to build one before? How much do all the parts cost? Is it possible to make a small scale one? When can I get the plans, and what equipment/tools do I need?

UPDATE To make this question a little more specific…

There are a few parts of the general design of a Telsa coil that I'm unsure about.

  1. The HV transformer – I've seen that some plans say you can use a microwave oven transformer for this, and other plans say that you need to stack them by wiring the primarys in parallel and secondarys in series, but then you can get insulation breakdown. Is a MOT a good choice? If it's not good to use an MOT, then what?

  2. The tank cap – the general idea is to get a load of lower voltage caps and solder strings of them in series to get the voltage rating you need, then parallel the strings together to get the capacitance you need… but how do you stop it arcing across the leads?

  3. Whats an RF ground? Does it mean drive a stake into the ground and attach one side of the secondary to that?

  4. Finally, nearly every circuit I build fails to work the first time for one reason or another, and I use my meter and scope to work out whats wrong… How can I safely test parts of the circuit without being zapped with 20KV?

Best Answer

  1. The problem with MOTs is the voltage is too low to make a sparkgap work reliably. A pair is just-about doable but still not ideal. A neon-sign transformer is an easier and safer transformer for a first-time coil.
  2. Insulation and /or spacing
  3. A ground with a low inductance path, and one that will not damage anything if it sees a HV discharge to it. i.e. not the ground pin on an AC outlet. Stake in the ground is ideal as long as the cable length isn't very long.
  4. You won't need to do any measuraments on the HV side. You will know if there is HV present - corona hiss, ozone smell, arc-overs etc.
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