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

[John Lyles]

In a crude way, the SCR/Triac dimmers for lighting do this.

Collins and later Continental Electronics had their HV and screen 
voltage soft started by a similar AC cycle chopping, using SCRs in the 
primary. This is in their FM transmitters, from a few kW up.
John
K5PRO

> Message: 2
> Date: Wed, 14 Dec 2011 20:38:52 -0700
> From: "Mike Baker"<k7dd at cox.net>
> Subject: Re: [Amps] Warm up and on time question...
> To:<amps at contesting.com>
> Message-ID:<04d401ccbadb$10702190$315064b0$@cox.net>
> Content-Type: text/plain;	charset="us-ascii"
>
> 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.

>