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Project Help and Ideas » Strobbing Tesla coil

November 01, 2010
by Hexorg
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Hello everyone :) I was having a few ideas about building a little strobbing Tesla coil - what i mean is - I press a button, one spark appears, I release the button, press it again, second spark appears.

schematics

The length of spark should be about 1-2 ft. Am I on the right path?

November 01, 2010
by mongo
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Almost...

Move the switch to the other side of the capacitors.

A Tesla coil is a little more complicated than this and most operate at about 5000V on the primary side.

The circuit above would give an inductive kick with the switch moved over but nothing like a spark more than maybe half a millimeter. That is because of the losses and inefficient mechanics of the typical transformer. A spark of 12 inches would be roughly 300KV and that kind of voltage would find a way to short out through the windings.

I'll doodle up a quick sketch and post it shortly for one that should work. If you want a single spark, you need to try and concentrate the output into something that you can see. That means a lot more current in the high voltage, which can be lethal.

November 01, 2010
by Hexorg
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Well I suggested a single spark, because I thought it would be much simpler then a continuous sparks. Idea was to make it jump from one palm to the other (having electrodes in both palms, so I'd rather make it non-lethal

November 01, 2010
by mongo
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It might work if you wore heavy rubber gloves but not bare-handed. The spark would find your hands before jumping through any distance.

Here is a little project.

Take two large bolts, like maybe 1/2" by about 5" long. Attach a length of wire to each one. Wire in series between the two bolts, a D cell battery, and an old power supply transformer through the secondary windings only. (leave the rest of the leads unconnected.

A simple demonstration of inductive kick would be to hold one bolt in each hand, touch them together to complete the circuit and then pull them apart to break the circuit.

DISCLAIMER: Do not do this if you have any suspected heart ailments, as it sends quite a jolt - From a 1.5 volt battery! Now imagine going through a major voltage increase.

This is also a good way to explain why you see clamping diodes across relay and solenoid coils in DC circuits.

January 14, 2011
by Hexorg
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Awesome experiment :D

So, with the collapsing magnetic field generating high voltages, do I still need a bunch of capacitors? Or can I just feed that to the primary tesla coil's winding? I suspect if I have capacitors, the high voltage generated by collapsing magnetic field will just bounce back and forward from capacitors to the coil, resulting in many sparks instead of one.

And is there a relation between coil's inductance, supplied voltage, and generated voltage at the magnetic field breakdown?

And of course, I will not hold anyone responsible for any damage done to me or to electronic equipment in the process of trying ideas posted in this forum.

January 14, 2011
by mongo
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The circuit at the top should have a resistor in series with the battery. It would be to charge the capacitors and prevent overloading through the coil.

Yup, it's the collapse of the field that generates the kickback. It can be 75 to 125 volts but at a relatively low current. It jolts ya pretty good but so far, hasn't hurt anyone that I know of.

The coil/capacitor circuit does have some oscillation to it but at these values, it is pretty short. You might get one or two decent spikes but it will diminish rather quickly through internal losses.

Tesla coils operate at high frequencies and are pumped by a high voltage in the primary coil and capacitor bank. The discharge side of the Tesla coil is usually a lot of very fine wire wrapped and shellacked heavily to prevent arc discharges between windings. The coil and capacitor circuit there also has the same properties but while the high voltage is present across a spark gap, it continues to generate these spikes.

January 14, 2011
by Hexorg
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Well the reason I didn't want to have any oscilations in the tesla coil, because essentially i wanted to connect it to the nerdkit and feed the sparking frequency from there, creating music :)

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