Help with building a tesla coil?

I want to build a tesla coil, but I want to verify with the instructables community that it won't blow up, burn down my house, turn into skynet, etc. Here's my plaaaauuuuuuhn:

For the transformer, I'll be using an old negative ion generator thing that takes in 120VAC and outputs 7.5kv(pic). For the primary, I'll use old speaker wire in  a cone shape (possibly using acrylic). For the secondary, I'll use 32- gauge magnet wire (pic). And for the spark gap, I'll use two bolts in a box, possibly with a computer fan cooling it. And for the capacitors, I'll just use an array of Leyden jars.

My questions:

1. What diameter should the coil form be? I have some random white tubing which has an OD of 1/2 inches, 1/2 PVC piping (which actually has an OD of 7/8 inches), and 3/4 inch PVC piping. And is there a better alternative to these?

2. Should I use chokes on the input/output of my transformer? For those, I think I'll just wrap a bunch of wire around a pen.

3. Should I varnish it?

4. How powerful will the EM be from this thing? Exploding computers aren't that good.

If I have made any errrors, please tell me.


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Mr. Apol8 years ago
You might start by looking at my Instructable for the bipolar Tesla coil. It isn't very big, and I haven't destroyed my computer or other electronics with it yet.

Generally, you will need a bigger secondary form that 1/2 inch PVC. For a small starter coil I would try 2 inch PVC or the equivalent cardboard tube, 12 to 18 inches long. You will need a lot more wire than a simple Radio Shack package. The bipolar coil has about 250 feet of 24 gauge magnet wire on it, and its only 10.875 x 1.85 inches. The primary is made of about 9 feet (total, including leads) of 12 gauge stranded copper wire.

Varnish (spar varnish, polyurethane, or shellac) is used to hold the secondary wire together and stick it to the form,  as well as improve the insulation of the wire to prevent short circuits and racing arcs.

For power, the ion generator won't do. It puts out 7,500 volts DC at very low amperage. You need a neon sign transformer or oil burner ignition transformer, which operate at 30 or 23 milliamps respectively. With enough amperage you can use DC, but it needs to be pulsed in some way to get the resonance you need.

Chokes are valuable to tame RF interference and to prevent high frequency feedback into your house wiring.
Shagglepuff (author)  Mr. Apol8 years ago
Actually, I have over 400 feet of wire. I also don't need it to  be too big. And the ion generator is AC at 60 hertz.

Note: What happens if a wire in the secondary crosses another?
The coil needs to be of some size or the output won't be much. It is possible to build coil with a 1/2 inch secondary, but the result will be in scale small.

The input voltage to the ion generator is 60 Hz AC. The output is 7.5 kV DC, hence the stream of negative ions. What matters too is the amperage. The ion generator does not put out enough power--amps--to make any size spark gap fire. Plus DC has to be pulsed to get the resonant effect a Tesla coil requires.

An ion generator is basically a voltage multiplier sealed in a block of plastic. It is rectified to remove the AC 60 cycle pulse.

Crossing wires in the secondary is a no-no. The spiral winding has to be smooth and bump-free or the effect will fail.
geek101023 years ago

well i say it is a possibility 7kv is a bit low but not impossible

you will most likely have to install the spark-gap in series with the primary for it to have a chance

given 7kv the gap would need to be <.5inch (maybe less than .25in) for a proper discharge, the low current is also an issue, thus your tank should be as low capacitance as low as possible. just need to figure out the tuning and it should produce a descent yet small electric field. don't expect any thing fancy

it is only 1watt at most. hey, its science, live a little.

just got a neat idea using negative ion generators, make a hybrid van de graaff

The_Hacker3 years ago
I== I made a mini Tesla Coil Runs on 1 transformer circuit from bug zapper and 2 caps
and a spark gap makes 1 cm spark
The_Hacker3 years ago
??? this work http://www.ebay.com/itm/DC-12V-High-Output-DIY-Air-Ionizer-Ionizer-Airborne-Negative-Ion-Anion-Generator-/121229646471
The_Hacker3 years ago
Howbout 20k Negative ion gen?