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Does a tesla coil need to be DC? Answered

Just a quick thing that I am not sure about for my tesla coil, does it need to be powered with DC current?

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LargeMouthBassBest Answer (author)2011-06-06

The most common implementation of a Tesla coil operates on AC.

First, a iron core transformer (neon sign transfomers being probably the most common) increases the line voltage (60Hz or 50Hz, depeding on where you are), to several kilovolts. This charges the primary capacitor to the point where a spark gap breaks down and conducts, allowing the primary capacitor and primary coil to oscillate. If the secondary circuit is tuned to resonate at the same frequency as the primary oscillatons, then you can obtain the tremendous voltage increase on the top terminal.

To power this conventional coil setup from a DC source, you would need to an inverter to drive the high voltage transfomer. I've never tried powering my coil from an inverter before.

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jj.inc (author)LargeMouthBass2011-06-06

Good, because mine is AC. Anyway, is it as hard as it sounds to achieve resonation between the two coils, or does a well wound secondary resonate fairly easily with not so great stuff like twisted copper tube and homemade transformers/capacitors.

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LargeMouthBass (author)jj.inc2011-06-06

By twisted copper tube, I assume you are refering to the construction of the primary coil. Copper tubing should work well.

Homemade capacitors can work OK. I'd try some of the beer bottle types or a parallel plate type submerged in oil.

As for a homemade transformer (I assume you mean instead of an actual neon sign or microwave oven transformer), I would recommend against it. Winding would be very difficult, and constructing it in such a manner that the output doesn't break down the insulation due to HV would not be trivial. Commercial NST's, for example, are potted in some kind of epoxy like material to avoid this.

If you have at least a decent ballpark estimate of the secondary resonant frequency, (from calculations), then it isn't hard to get the primary tuned to it. You can add/remove caps and/or change the primary inductance by taping off at a different turn of the coil.

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jj.inc (author)LargeMouthBass2011-06-07

o, well, what exactly are these calculations. The instructables I have read on building tesla coils have never mentioned it. I have about 1358 turns on my secondary coil it has a 2.25" diameter and it is 29.75 inches tall 2 inches over my estimate based upon wire thickness. So that means I may have 1480 turns, or just a little thicker wire. Any ideas on how to resonate it. Also, will it work without resonation at just much lower performance?

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You can power it with an ignition coil or something that you could drive of pulsed DC.

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freenergyfuture (author)2012-03-03

yes, a tesla coil as Nikola Tesla used himself is operated with only DC power of extreme on/off frequencies.

download the pdf from this link: http://depositfiles.com/files/ubulzr1t8

skip past the first chapter and read on about how Tesla discovered the benefits of high voltage high frequency on/off Direct Current power.

I am in the process of building a Don Smith Tesla coil version.

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The MadScientist (author)2011-06-07

A Tesla coil will operate with DC or AC.
An AC coil will have to have a capacitor and spark gap that matches the specks of the high voltage transformer (in terms of how fast the transformer can charge the capacitor) this can be quite difficult especially if you don't have access to store bought capacitors.
A DC Tesla coil is much simpler and much easier to make your main focus is powering and resonating it.

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So, How would you make a DC Tesla Coil?

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Simply tune the tank circuit with the secondary coil and connect your HV DC power source to the tank circuit.

http://deepfriedneon.com/tesla_frame6.html it has all the calculations you will need.

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