Quote:
Originally Posted by russell_w_b
I haven't studied this yet, but if your pulse transformer is designed to work into a specific burden like a current transformer - in your case, 300mA - you really shouldn't run it open-cct as there will be a very high voltage developed across the secondary. Can you hang a resistor across the secondary winding so that it will load it up to 300mA?
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Hi Russell, this is a good point indeed. I hadn't thought of the current transformer analogy, although I am familiar with the danger of leaving a current transformer o/c. I'll load it up as you suggest and see what happens. In the meantime, I've somewhat reinforced it with additional insulation. I think one side of the secondary was normally returned to the core - I'll have to check.
Quote:
Originally Posted by russell_w_b
What sort of current are you passing through the primary winding of your pulse transformer and how many turns has it?
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I can't assess the peak current. RMS is the max that my DC bench power supply is capable of, 4A .However, I've also put a fat electrolytic right across the Source-Drain, so that will up things a bit. Also, the switching device is a MOSFET being hard switched and dI/dT is very high as it's switching in 25nS or so, so large pulses.
The manufacturer's design switch was a much slower IGBT, with a long transition time, I think 225nS.
It appears to have around 8 turns, heavy Litz. That would make sense as the DC bus for the inverter it came from was half-wave rectified mains.
I'd appreciate any comments, thank you!