VERSION 7 - VTTC

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This is probably the first tube tesla coil I tuned. The secondary coil has a self-resonant frequency of about 2400kHz, so I tuned the primary circuit by using a 40pF capacitor (achieved by using two 75pF ceramic disc capacitors in series) in parallel with about 21 turns of 14 gauge wire on a 4" PVC. The transformer provides 760V and is very large; it was salvaged from a heavy rack-mount power supply. For your information, the 807s have a plate voltage maximum of 750 volts, but they can take more voltage if the grid is not too negative.

Plus, the HV source (760V) is AC (alternating current), but the tubes only operate on the postive half cycle because the cathode does not emit electrons when it is postive and the plate does not take in electrons when it is negative. This type of operation generally results in a 60 cycle hum. In this case, the 807s draws intense currents making my transformer hum and rumble. Below is the schematic diagram of the version 7 VTTC.

Parts List/Specifications
V1 - Three type-807 tubes (in parallel)
R1 - 4K ohms, ~20W
R2 - 50K ohm, ~10W
C1 - ~40pF 10kV
C2 - .001uF 600V
L1 - ~21 turns 14 gauge below L2 on 4-inch PVC pipe
L2 - 20 turns 24 gauge above L1 on 4-inch PVC pipe
L3 - ~270 turns 24 gauge on 2-inch PVC pipe - 6 inches from bottom to top
T1 - 760V, 6.3V power transformer

The discharge length generated by this VTTC is about 1-inch long, which not as impressive as I thought. However, don't let a inch discharge fool you, it will give intense RF burns and mess up an AM radio because of the high current output.

Version 7 VTTC Pictures:

Version 7 VTTC

Close-up of homemade tube sockets

1-inch discharges

Hot Arc

Plasma-globe lightbulb animation
GENERATED BY VERSION 7 VTTC