Small Spark Gap Tesla coil (SGTC) #4
By Radu Motisan Posted on September 8th, 2011 , 2533 Views (Rate 3.07)
This is an update to my last SGTC project, as presented here.
In just a few words, this is a SGTC, that takes 10-20V in, uses a Royer oscillator to drive a half wave rectified flyback, charges a bank of capacitors, and uses a spark gap as a relaxation oscillator to drive the primary of the tesla coil. Schematics in the original post (link above).
1) The capacitor bank now uses 24x 6800pF 4KV good quality Russian capacitors (Polyethyleneterephthalate foil), as found here. The capacitors are connected for 8KV 40.8nF on a Bakelite board. The entire setup is enclosed by a PET plastic foil. The capacitors use a bleeding resistor, made of 9x10MO 0.5W resistors connected in series. Here are some pics:
2) The spark gap uses two sphere shaped screw bolts, inserted in a plastic pipe to reduce noise. As you know SGTCs can be very noisy, so this helps a bit. Ideally, I should have used a ceramic pipe, but I didn't have one. Plastic can melt on continuous use, but I had no problems so far. The spark gap distance is adjustable via a screw: