A common part used to create a high voltage is a CRT flyback transformer, having been a ubiquitous junk pile component. So many attempts to use them rely on brute force, with power transistors in simple feedback oscillators dropping high currents into hand-wound primaries, so it’s refreshing to see a much more nuanced approach from [Alex Lungu]. His flyback driver board drives the transformer as it’s meant to be used, in flyback mode relying on the sudden collapse of a magnetic field to generate an output voltage pulse rather than simply trying to create as much field as possible. It’s thus far more efficient than all those free running oscillators.
On the PCB is a UC3844 switch mode power supply controller driving the transformer at about 25 kHz through an IGBT. We’d be curious to know how closely the spec of the transformer is tied to the around 15 kHz it would have been run at in a typical TV, and thus what frequency would be the most efficient for it. The result as far as we can see it a stable and adjustable high voltage source with out all the high-current and over heating, something of which we approve.
Need to understand more about free running versus flyback? Read on.
I did something similar but with a quad op-amp, some transistors, and one 250v power transistor to drive the primary. The results was my custom flyback transformer and circuit produced a wide range of needed voltages and only draws 0.25 amps when no load was attached. One thing to remember is even the primary coil produces its own high voltage so its important to not waste that energy with a flyback diode or power transistor rated at too low of a voltage.
But can it play Megalovania?