Powering a Tesla Coil with a 12 volt battery--help--

[Kalrag]

So I have been wanting to build a Tesla Coil for a while now, and I did not want to make a large one, just enough for a 4 or 5 inch spark. That being said I began searching the internet for designs when I stumbled upon the 12 volt battery variation. The idea is that the 12v battery would drive an ignition coil that would in turn power my coil. The only issue as of today is my ignition coil. I plugged everything in as shown, but did not get any sort of spark on the output as expected. I then measured the voltage to see that I was only getting 11 volts out of it. Can anyone point me in the right direction of what I am doing wrong? I did the same thing for another coils and got the same results. Here is the link for the design:

http://www.instructables.com/id/Mini-Tesla-Coil-1/

 

[Kalrag]

This was another image that I was working off of...

 

[zoki85]

Are you switching on or switching off to get high voltage? What is your breaker?

 

[Kalrag]

I believe the breaker is only acting as a switch. I did not have a switch when performing my testing.

 

[NTW]

If I were to build a Tesla Coil, I would first of all try to make the construction as neat and safe as possible. Dangerous voltage is around...

I would also try to calculate convenient values for the primary coil and the capacitor, so to have a powerful oscillating circuit there. Besides, I don't know how your 'Leyden jar' is built. I would make the capacitor with rigid plastic or plate glass and copper sheets...

Good luck and be careful...

 

[zoki85]

I believe the breaker is only acting as a switch. I did not have a switch when performing my testing.

Well then, the simple mechanical breaker probably can't interrupt circuit fast enough to get the high voltage going.

 

[Windadct]

You need a switch. That is what makes it work, the DC current flows in the coil, opening the switch stops the current, but you can not instantaneously change the current in an inductor - and the inductor creates a large voltage trying to maintain the current.

 

[Kalrag]

Then that must be what the driver circuits are that I have seen are the more in depth Tesla coils. These circuits would include a 555 timer which is the switching that zoki may be referring to. And also would explain why most people were using these ignition coils with AC current instead of DC. So explain to me why smaller coils did not include this driver circuit?

 

[zoki85]

Maybe give it a try with some capacitor in parallel, between your breaker and ignition coil...

 

[NascentOxygen]

You need a way to repetitively make and break the connection to the primary to keep getting sparks. A simple demo could probably be made using a saw blade in a series circuit with the battery and primary winding---rubbing a copper wire back and forth over the teeth will achieve this.

Or just keep tapping the wire to one of the coil's 12v terminal posts so you manually make and break the connection. A constant connection just flattens the battery without producing any sparks.

 

[berkeman]

This thread is a bit too dangerous for my taste. The OP doesn't have the experience yet to be messing with high voltages. Thread is closed.