Re: PIRANHA-III Power control? (fwd)

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Original poster: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Mon, 18 Dec 2006 16:27:29 -0700
From: resonance <resonance@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: PIRANHA-III Power control? (fwd)




The biggest problem that these triac circuits have is from interference on 
the mains and interference in the triggering circuit.

I'm researching the 555 with opto-isolated trigger driver that operates off 
a rectified 12 VDC source, very similar to the cmpnet.com/chipcenter 
schematic.  I think this driver  with a 40 Amp alternistor will work, or 
perhaps we will have to use back to back 50 Amp SCRs.  Even so, I think that 
a good RF filter should be incorporated to prevent any kickback spikes in 
the SCR circuit and I'm also advocating an 18 inch long x 2 inch ID PVC tube 
filled with cut 1/8 inch steel rods to help clip some of the larger surge 
current peaks.

Presently I'm having Matt wind up some current clipping reactors , and 
ordering some alternistors and SCRs to do some "climbing arc" MOV tests 
early in mid January.

I'm really excited to see the solid state experts on the list addressing 
this problem.  Getting rid of the big, heavy, and now very expensive variacs 
is long overdue for Tesla coil builders.  Hopefully we can all pitch 
together to solve this problem.  I think this is a very worthwhile project.

I'm leaning toward the dual SCR circuit with 555 control.  If the 
driver/control portion works well with 50 Amp SCRs and MOTs it should also 
work well with pole xmfrs, potential xmfrs, and the DRSSTC designs so we can 
all have solid state control without the expense and weight of large 
variacs.

If we can come up with a good workhorse for TC control I will do the 
schematic in MultiSim and run the board design in my Ultiboard program ---  
then we will all have a source of PCBs to tackle this problem.

I also plan on obtaining the tanks, agitators, and chemicals to run my own 
boards in batches of 10 or 20 so we will not have to rely on a PCB house to 
run these for us.  I have plans to order this material in mid-Jan as we need 
different types of board from time to time for various proects.

Dr. Resonance