[Amps] Crowbar components

[Ian White, G3SEK]

Frank Goenninger wrote:
>Hi all on the list:
>
>There have now been several posts here pointing
>to
>
>http://www.qsl.net/oe5jfl/flashover.htm
>
>as a suitable crowbar circuit. I want to copy that
>one...
>
>When searching for suitable components I could not
>find a suitable opto-coupled Diac as shown in the
>mains circuit.
>
>My HV transformer will draw abt. 21A of current so
>I need a Diac able to withstand that or I have to
>substitute that part with ??? A diac controlling
>a thyristor ? Or ??
>
>Are there any such diacs or what would a suitable
>replacement circuit not altering speed too much
>look like?
>
It is a normal solid-state relay. (I am not sure if it is the 
zero-crossing type... you could check with Hannes.)

Other information....  L1 is simply 10m of wire, random-wound. The 
thyristors are typically 1200V or better, 8A or better (8A is the 
continuous rating, but these are being used in their pulse rating which 
is much higher. Since it is only a single pulse, TO220 packages with no 
heatsinks are fine.) IRF make some nice 1600V TO220 devices at a good 
price.

Frank, I will scan the original DUBUS article in German/English for 
you... but it can't be until Monday.


-- 
73 from Ian G3SEK         'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek