Transformer DriverI built this basic circuit over 40 years ago as a 14 year old, the Astable Multvibrator, since then I have used it on many occasions for lamp flashers and oscillators etc.
Then I got to thinking that I should build one again, I found some KSP2222A's, and so out came the stripboard and I got to work, but rather than just having one MOSFET, I went with 2, these were mounted on heatsinks, and an enclosure was fabricated with some other bits.
Testing the oscillator on 12 Volts, I got a frequency range from 1.2 - 2.3 KHz, but I could go for a higher voltage as the transistors are rated for about 30 Volts, and that means higher frequency.
Here is my version of the diagram, the BC546's replaced with KSP222A's
I decided to go with 2 opposing outputs, this means I can drive a single transformer as the original, or 2 transformers out of phase to get higher output voltages, or a centre tapped transformer, the confgurations are shown below
The driver circuit only needs a low power supply to run the oscillator, so you run a high power supply to the transformer where noted, and connect the other side of the primary to the output terminal(s), the negative connection is taken through the driver box via the Mosfets to the outputs, so this wiring needs to be more substantial. Another advantage is that the driver can be powered by 12 volts, while the transformer can be powered from something higher,
A few things to note:
You can omit the diode if you are sure that you will connect it properly, or replace with a lower current one if powering the tranformer/flyback from a different supply (remembering to keep the negatives connected from each supply),
If the transistors are rated correctly, and you power this correctly, you can also omit the 100R resistor, my circuit for instance could run up to about 30 volts without the resistor, hgher voltages will mean higher frequency with these values.
Here is the finished driver
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