Can anyone help with this Tesla coil?

[Aidan5566]

I have recently made a Tesla coil using this schematic: and I’m having problems. The secondary coil is roughly 900 turns of 30awg magnet wire and the secondary is 8 turns of 14awg wire. The only difference from mine to the schematic is the 50kohm resistor was replaced by a B50K potentiometer. The circuit is powered by four 9 volt batteries in series, although in the picture they are in parallel. I have also tried a 15 volt transformer to no avail. The transistor gets very warm very quickly and the coil has no plasmatic discharge from the secondary and it doesn’t generate wireless electricity to flourecent lights. Am I doing something wrong or is the circuit wrong please help.

 

[betwixt]

Most likely you have the primary winding the wrong way around. Try reversing the connections to the primary (transistor collector) side and see if that fixes it.

Note that connecting batteries in parallel like that is not a good idea and should only be attempted if all the batteries are the same type and state of charge. It is possible to explode them if one or more is sub-standard so be careful. If you want more voltage you should wire them in series + to - in a chain instead of across each other.

What did you use to fix the transistor to the heat sink?

Brian.

 

[Aidan5566]

I'm not sure I'm fallowing. How do you want me to reverse the primary coil?

 

[betwixt]

Just swap the connections to the thick black primary coil. Take the white wire and the green wire and connect them to the opposite ends of the black coil.

A simple oscillator like that works because there are two signal inversions, one is in the transistor itself and one is between the primary and secondary winding of the Tesla coil. If one of the windings is backwards you do not get the second inversion and it fails to oscillate. You could reverse the connections to the secondary instead of the primary to get the same effect but that would be hard and dangerous to implement!

Brian.