Re: PIRANHA-III Power control? (fwd)

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Original poster: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Tue, 19 Dec 2006 10:20:58 -0700
From: resonance <resonance@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>,
     "Vodvarka, Brian" <brian.vodvarka@xxxxxxxxxxxxxxxxxx>,
     Gerry  Reynolds <gerryreynolds@xxxxxxxxxxxxx>
Subject: Re: PIRANHA-III Power control? (fwd)



I have had discussions most of the day today with ON Semiconductor, Teccor 
Electronics, and STI Semiconductor.  Their application engineers were very 
helpful and sent me several informative diagrams.  Brian and I are digesting 
their content and will propose a complete circuit in the next few days.

I think we have the problem solved using optoisolated 555 timers driving 
back to back SCRs.  Teccor especially has one that is rated for 65 Amps, 
isolated mtg, and with back to back will handle up to 91 Amps Irms.  All for 
only $5.60 from Digi-Key!!  p/n is S6065J.

I will be doing experiments with our iron core current peak clipping chokes 
using this setup.  We hope to have a complete solution by Jan 15th for the 
variac elimination problem.

According to the engineers I have worked with this solution should also 
enable us to use very cheap control even with pole pigs!!  In a box weighing 
under 10 lbs.

The engineers also had very good snubber suggestions that I will incorporate 
into my drawings.

Dr. Resonance
>
>
>
> ---------- Forwarded message ----------
> Date: Mon, 18 Dec 2006 21:13:01 -0500
> From: BRIAN FOLEY <ka1bbg@xxxxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: PIRANHA-III Power control? (fwd)
>
> Hi, i think they must have "x'ed" out the values. made them unreadable as 
> to
> values. triac's are ok but limited in power. the dual scr leaves the 
> option
> open to use brick sized scrs pairs mounted on a good heat sink should be
> able to drive most anything. i probably have 50 lbs of scr bricks i have
> saved from VFD's and scr motor controls. then a whole stack of scrs of
> conventional shape. i suspect most of us have a few scr bricks hiding in 
> the
> drawer. cul brian f.