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?

  • 2
    \$\begingroup\$ I suggest you try to make your question more specific. It requires a textbook-sized answer in its current form. \$\endgroup\$
    – tyblu
    Jan 8 '11 at 18:05
  • \$\begingroup\$ "nearly every circuit I build fails to work the first time for one reason or another"... perhaps because you are being careless? no offense intended, just sayin' that if you are careful to do everything right the first time you'll save time. edit: that's not to say that my projects work the first time either :) \$\endgroup\$
    – Isaac
    Jan 10 '11 at 13:23
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    \$\begingroup\$ there are two quite different ways to go, it might help to decide whether you want to build a 'solid state tesla coil', or if you want to go with strictly 1890's tec. \$\endgroup\$
    – JustJeff
    Jan 10 '11 at 22:20
  • \$\begingroup\$ I built one, but we eventually decided to condemn it because it was arcing and blowing breakers. \$\endgroup\$
    – endolith
    Jan 11 '11 at 20:49
  • \$\begingroup\$ @endolith - despite having the parts, i've avoided building one for a long time, for just the reasons you cite. however, lately i've been wondering how much harm a small one could cause. Which leads me to ask, what were the specs of your machine? Even just approximate values are of interest. \$\endgroup\$
    – JustJeff
    Feb 9 '11 at 22:58
  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.

Lots of info to research can be found here.


I always thought about it but never did. there is a chap in western australia who built some big ones and records videos and has a blog about it, not sure of the name now.

Good luck with it should be fun! do be careful around it tough, cos they can generate some seriously high voltages :)

  • \$\begingroup\$ I know, I think I've seen the same videos... He stands in a faraday cage and watches a huge spark hit it inches from his face. \$\endgroup\$
    – BG100
    Jan 8 '11 at 17:46
  • \$\begingroup\$ yup - thats the one! \$\endgroup\$ Jan 9 '11 at 13:15
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    \$\begingroup\$ I don't understand why this gets an up-vote; it gives no information which comes even close to answering the question. \$\endgroup\$
    – stevenvh
    Jan 10 '11 at 12:14

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