[Amps] Solid state relays..again

[John K Gotwals]

>Sounds like my old 50A Astron. Big transformer and rectifiers. Pass
>transistors for a regulator.  Once in a while that thing turns on with a
>WHummpppp and a low frequency ringing that just trails off.

My guess is the noise has to do with the hysteresis loop of the transformer 
core and where on the loop the power supply was at turn-off and the 
following turn-on.
John, N9JG (john at gotwals.com)