This is a Royer oscillator which is a relatively high power self resonant circuit useful for generating high voltages from flyback or other ferrite transformers. Output is probably around 2000 VAC. The arc stretches out to about an inch at a power of up to 300 W.
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This version is adapted by Vladimiro Mazilli. The supply is made almost entirely from parts from a scrap microwave ovens which are of the electronic type (the light weight ones). I used 2 IGBT’s and one of the heatsinks along with the small toroid inductor. The main ferrite transformer, also from the microwave, had the primary heavy Litz wire removed and replaced by 10 turns centre tapped driven by the simple Royer type circuit. I have also removed the spacers between the cores. Non microwave parts included the main capacitor, two 12 V Zener’s, a few resistors and two high speed diodes (BYV-29 500 Volt, 9 A, 60 nS). The input here is about 30 V 10 A (300 W) with resonance at about 70 kHz. The IGBT’s are rated at 600 V 30 A and only get slightly warm in action but the cap will overheat if the resonant frequency is too high.
Above is a modern TV flyback transformer with core spacers removed and the exposed core wound with 10 turns centre-tapped of rather flimsy wire running about 250 W. Note the spark is longer than the transformer.
An older but larger flyback supply.
The older style flyback supply transformer here has the spacers removed and is a little more efficient. It is running at 44 kHz at 30 V, 6.3 A. The meters are lying.
The right photo shows a 1 inch DC arc with a 30 nF 40 kV cap added to the unit which now has a dedicated 37 V 10 A power supply. The intense spark is seen behind the filter made from 2 welding goggle filters.
Related pages
Variable frequency flyback supply 4 kVAC
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Photo Date: Oct 30, 2004