Re: [TCML] triac or scr choice

[sparktron01@xxxxxxxxxxx]

Folks 

An interesting experiment (which we are in early stages of performing) is replace the 
stoogy old SCR with a nice gleaming new IGBT. Why? Well... 

1. You can cut if OFF in microseconds, thereby protecting the VT is anything goes POOF! 
2. You can turn it on with LESS drive then an SCR, and it will turn on at least 10X faster 
(again easily single digit microseconds). 
3. An IGBT has arguably as good a di/dt rating as a SCR. If you think not, how about 
those things called eh eh DRSSTC's out there, and their "little peak currents" (1kA + ;^D ) 
4. 1.2kV devices are available from multiple sources, and Ic rating does not have to be 
outrageous. A 10A device is capable of controlling a 10-20kV VTTC...EASILY with 
less then 30W dissipation when on ( at a Vce ON of betwen 2.2-2.5V) 
5. Staccato control will have to be modified to stay on during postiive alternation, or much 
more interestingly, turn the oscillator off early (150-500 microseconds), just like a 
DRSSTC. I "think" that might reduce the VT dissipation as well, "just a little" ;^D 

Regards 
Dave Sharpe, TCBOR/HEAS 
Chesterfield, VA USA 


----- Original Message ----- 
From: futuret@xxxxxxx 
To: tesla@xxxxxxxxxx 
Sent: Wednesday, February 25, 2009 5:41:44 PM GMT -05:00 US/Canada Eastern 
Subject: Re: [TCML] triac or scr choice 

Christoph, 

It's better to use an SCR. THey are built in a more robust way than 
a triac. 

John 
-- 


-----Original Message----- 
From: Christoph Bohr <cb@xxxxxxxxxxxxxxx> 
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx> 
Sent: Wed, 25 Feb 2009 7:29 am 
Subject: [TCML] triac or scr choice 



Hello everyone.. 

which type of triac or similar device should one use in 
conjunction with a VTTC staccato controller? 
I have found the shematic at the eastern voltage research 
homepage and was wondering what kind of device I could use 
to swith the cathode of a tube around 1KVA 

Any suggestions are appreciated. 

regards 

Christoph Bohr 

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