This one was called "MiniTC" because it was 10 cm (4") high, built using the wire taken from the secondary of a car ignition coil. The wire was so thin (AWG#40 ??) that finally I forgot the counting I was doing and continued until it was wound. I suppose it had something around 1200 turns or so... The capacitor bank was 3.8 pF (red caps) and on the right side of the general view you can see my regulated spark gap, salvaged from an old medical high frequency machine made in Germany during the 30s. In fact this spark gap although very tiny, is one of the best I've ever seen and tested. It has a pair of tungsten electrodes which can be regulated at 1/10 of mm and even after 70 years of use, runs smoothly!

This little one was powered with my HVFB generator. More details about this equipment you'll find in the next topic.


This one is one of my little Solid State driven TCs:

It uses a solid state high voltage generator HVFB to excite the primary circuit of the Medium TC, it can give about 70 kV at 1.6 MHz.

Two nice features this TC has are:

- With the HVFB controls we may adjust voltage, frequency and duty cycle over a wide range.

- The spark gap regulation adds a further tunning.

Although it gives only 5 cm sparks, these are 1600 kHz ones, so you can put your hand without receive any shock and what is more interesting: you can play around safely with its HV & HF output!!! (My 6-yr old son loves to hold in his hand neon tubes and watch it light on when sparks are jumping from this coil: -Watch pa, no wires and it lights on! :-))))))

Here you may see what the Medium TC looks like when the power supply is at 30V, and either the HVFB and the spark gap are tunned for best performance.

The corona size can be deduced considering that the secondary diameter is 4 centimeters (aprox. 1"1/2), not bad for a 30v/2A supply (60w).

High voltage output was estimated measuring spark length and considering 10 kV/cm. Sparks of 5 cm (2") long gives 50 kV, but from my point of view this "rule" is just a rough aproximation, so I believe the coil's output it's a little bit higher, perhaps 70 kV...

Finally, a general view of the equipment: the Power Supply (max 30V/3A), the HVFB with the 3 main knobs (frequency bands A to E, and duty cycle control: on time/off time). The red plug on the right side of the HVFB is the high voltage output that goes directly to the spark gap (hidden behind the primary coil). The primary here it's a little bit bigger than it should be, because I've experimented with other tap points.
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