[Amps] Step start resistors, another solution

[Alek Petkovic]

And Emtron use a thyristor slow start circuit in all their amps. I have not 
seen any circuits of this but    it couldn't be too difficult.

It sure works better than anything else I've ever seen. Soft, silent and 
very effective.

73, Alek
VK6APK

At 04:52 PM 5/01/2004 -0500, Paul Christensen, Esq. wrote:
> > Another way to limit the surge is to use Crossing Relays.   I use two 40
>amp
> > crossing relays on a 4000 volt/2 amp HV supply, and it works great.
>These
> > work by not completing the circuit until the amp draw would be zero during
> > the 60 cycle phasing.
>
>I've seen solid-state zero-crossing switches used for this purpose.
>However, maximum current is achieved in just 90-degrees at 60 Hz (assuming
>no zero reactance in the circuit).  This equates to only 4 ms.   It this
>sufficiently enough time to limit filament current in-rush, especially with
>directly-heated cathodes?
>
>-Paul, W9AC
>
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