Post #3737999
2026-07-10 17:48 UTC
@upofadown@mstdn.ca What you describe is the reason why transformer coils don't behave like inductors. In our case though, we have exactly the problem that the *primary* on one side is open circuit because the transistor is off, making that part of the *secondary* behave like a high impedance inductor in series with the load, at least for every other half wave that is.
It looks rather pathological in LTSpice, too:
second picture is the "good" case where all output transformer coils are coupled together, first picture the non coupled case of two side by side ferrite sleeves, each coupled to one transistor.
Replies (2)
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@upofadown@mstdn.ca 2026-07-11 11:00
@Quantensalat@scicomm.xyz When the transistor is on, then the current through the inductance will ramp up. When the transistor turns off, the current will continue. That might mean that the voltage across the inductor will greatly increase (inductive spike) enough to cause some component to conduct in an abnormal way. Perhaps that is what is happening here? It might be interesting to look at the voltage across the source and drain of the transistor.
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@vk3kri@mastodon.radio 2026-07-10 20:10
@Quantensalat@scicomm.xyz @upofadown@mstdn.ca I have always maintained that this arrangment is two seperate transformers, as you have modeled in spice.