SCR/Triac pig controller? (fwd)

---------- Forwarded message ----------
Date: Wed, 13 May 1998 19:12:02 PDT
From: Bill the arcstarter <arcstarter-at-hotmail-dot-com>
To: tesla-at-pupman-dot-com
Subject: SCR/Triac pig controller?

 Seems like one problem with powering the larger coils is the scavenging 
(and paralleling?) of enough variacs to handle the 7+ KVA which might be 

 So why can't I just build a large phase-controlled scr/triac controller 
and run my pig off this huge "Light-Dimmer"??

 I understand the design of the scr drive circuitry is slightly 
complicated since the load is inductive (need snubbers, etc), but that 
doesn't seem insurmountable.  I'd also need some good solid 
filtering/emi/efi construction techniques to minimize hf/rf getting into 
the gates or control lines, etc...

 The output voltage of our 60KVA x-ray transformers are controlled by 
phase controlled scrs/GTOs etc.  (that's what made me think about it)

 Ya-ya. I know solid state and tesla coiling don't usually mix well - 
but I think in this case the benefits would be worth the effort.

 I'm presently using a bank of four scrs on the output of my (previously 
AC-only) welder.  This gives me 180 amps DC in conjunction with my hf 
arc stabilizer- with no ill effects (ie - no uncommanded triggering of 
the scrs).  Granted - I had to do a few HF bypassing tricks on the gates 
and I'm not doing phase control - just using it as a huge switchable 
full-wave bridge...

 If someone would tell me why this won't work as a pig controller before 
I go to the trouble of trying it - I'd really appreciate knowing!!

 Heck - maybe I'll go buy those ignitrons I saw up at the scrapyard...  
That'd take care of it.

-Bill the arcstarter
Starting arcs in Cinci, OH

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