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Plasma flame - high current VTTC

     The plasma flame is a simple tube oscillator, generating discharge into the air. It is very similar VTTC, but works with smaller output voltage and higher current. Also, the operating frequency is much higher. More description is unnecessary because of photos and especially videos below :). I also based the Sound modulated flame (audio VTTC) on this circuit.
I used self oscillating circuit with vacuum tube GU-81M, then i connected these two tubes in parallel. The high voltage of the mot MOT is, in the first version, half-wave rectified, in the second version it is bridge-rectified. High-frequency current is blocked by a pulse capacitor 7n5/4kV​​ connected in parallel to the high voltage supply. You can control the MOT input voltage by a variac to regulate the anode voltage, but it is not necessary. Heater voltage ensures rewound MOT with 13 or 14 turns. Heater is switched on in two steps - first through limiting ballast, then directly. The vacuum tubes are operating in triode connection. As a biasing resistor is used incadescent bulbs 60W/230V. Secondary builds on top of the primary. All windings are wound with 1mm diameter wire on a 105mm diameter pipe.

     WARNING !!! Tesla coil is extremely dangerous device! Without knowledge of the principles of working with high voltage, you should not construct it. All parts are connected directly to mains. MOTs produce high voltage with current of several ampers. Tesla coil is causing a broadband radio frequency interference. Electromagnetic radiation can damage electronic devices or storage media. During the operation it produces ozone (O3) and other toxic gases, must be ventilated! Everything you do at your own risk! For any injury I do not take any responsibility.

Schematic of a plasma flame VTTC with one GU-81M

Schematic of a plasma flame VTTC with two GU-81M

Plasma flame.

Measuring the operating frequency. For measurement purposes I set low power and added filtration. Frequency counter shows 8.16 MHz.

Measuring frequency after a slight realignment - 5.43 MHz.

Fluorescent in oscillator plays all the colors :)

Plasma flames, melting glass.

High frequency high voltage (8MHz) between two plates of glass.

Electric tree on Bakelite. HF HV draws interesting shapes on bakelite (kartit).

Bulb connected :).

The plasma flame (less power with 1 GU-81M), discharge to a screwdriver.