>> To the extent that "faster diodes" shorten the rise time of the waveform,
>> that makes some sense. Another primary mechanism is a current loop that
>> is
>> physically large, thus generating a strong magnetic field. A third
>> mechanism is a "pin 1-like problem" with external wiring that puts noise
>> on that
>> wiring as a common mode signal. The capacitors across the diodes
>> suggested
>> in the reference are essentially reducing the HF current that excites
>> these mechanisms.
Jim,
I can 100% understand why this would be the case where a chopper is used
ahead of the transformer primary (e.g., typical SMPS) and the secondary is
rectified and filtered. The faster rise time results from the chopper
located between the common-mode AC line filter and the transformer primary
with the intent to up-concert 60 Hz to some higher frequency to make the
transformer smaller and lighter with smaller smoothing components after
rectification.
But what I don't understand is why the diode type makes a difference on a
perfectly sinusoidal 60 Hz secondary feeding the rectifier diodes in a
linear power supply. That appears to be the type of supply being modified
in that link from Dallas Lankford. I'm really lost on that one.
Paul, W9AC
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