As I learn the theory behind tesla coils, I don’t have the money to make a real one right now but I figured I could make a small scale tesla coil:
* Bug zapper to step up the voltage. Technically since I was using 3V instead of the 2.4 originally in the device the capacitor is a little low for what could create better sparks.
* 2xAA batteries (and battery container)
* 2 metal rods for a spark gap (I used rounded end bolts)
* 30AWG magnetic wire for the secondary
* 14AWG solid core wire for the primary
* toroid (I used a 1″x4″ polished aluminum)
* 1(15/16) PVC pipe
Not going into theory but here is the gist:
Instead of AC mains I am using a 3VDC source from the batteries. Using diodes and a non-inverting switching driver to pulse the current it is then stepped up by a 1:100 so the primary circuit is working with 3000V and 0.0024A (roughly). Once the capacitor is charged up, the spark gap ignites because there is enough energy to bridge the dielectric of air. As the air ionizes the capacitor can pretty much fully discharge and you have an RLC circuit with a low Q that (hopefully) is at the same resonance as the secondary circuit.
There is a lot more calibration to do. This isn’t my final Ls or Lp. My final design will have a 960 turn secondary with a reverse conical inductor for the primary using copper tubing that can be tapped for calibration and better sparks.
Here is the result of my math:
*resonant frequency: 602.157 KHz
*N (turns): 960
*H (height): 245mm
*Cp: 0.0025uF (actual is 0.0022uF)
Reverse Conical Design using 1/4″ copper piping:
* N (turns): 20
*ID (inner Diameter): 3″
*OD (outer Diameter): 7.51375″
* W (“Height” of winding): 6″
*A (Average radius of coil): 2.62844″
(theta) angle from horizontal: 64.019 deg
Fun project. Should be able to complete it soon when I have the time. But the results so far have me entertained.