[Amps] Warm up and on time question...

[Mike Baker]

Speaking of warm up times and filament life got me to thinking about a
ramping switch system for the whole power supply.
As I understand it there are devices which will chop up the AC sine wave
into pieces like a PWM and slowly add more and more pieces until the full
sine wave is present on the load. I also understand they can be used in
reverse. Sort of like having an electronic Variac on the input side of the
supply.
Do any of you have a circuit diagram for such a system or could point me in
the right direction?  I am not even sure what to call what I am looking for.
It sounds like a ramping soft start system and that would solve a lot of
problems with initial turn on of the filaments and the Plate supply.

Thanks in advance.

Mike Baker  K7DD
K7dd at cox.net
All QSO's are uploaded to LOTW and EQSL.