Thread-topic: Hockey Puck SCR as spark gap replacement
A spark gap is also not at risk of exploding as IGBTs and other high power semiconductor devices are prone to do under tesla coil duty. Much easier on your wallet and less aggravation. A good RSG takes some time to build well but once completed, they are practically indestructible. On the downside, spark gap coils require a lot of iron, as in big heavy transformers, so the portability factor is down.
Steve White
Cedar Rapids, Iowa
----- Original Message -----
From: "jimlux" <jimlux@xxxxxxxxxxxxx>
To: tesla@xxxxxxxxxx
Sent: Wednesday, December 5, 2018 7:50:39 AM
Subject: Re: [TCML] Hockey Puck SCR as spark gap replacement
On 12/4/18 11:24 PM, Greg Peters wrote:
> Hi all,
>
> I know this has been discussed before but forget why it was dismissed. Can
> someone remind me?
>
I think the IGBT approach was found superior -
SCRs are unidirectional, and don't switch very fast.
You'd need back to back SCRs.
Sort of like the use of a hydrogen thyratron (which has also been
tried.. they're fast to turn on, not as fast to quench)
There's also the voltage issue - you'd need to stack them to get the
voltage you need for a NST.
I think that observation is what drove the initial "off line tesla
coils" - using the rectified power line as a several hundred volt DC
bus, then using commercial power semiconductors - I seem to recall that
some folks did start with SCRs, but then IGBTs (which are much faster)
took over, and the rest is history with the DRSSTC - which is
essentially a high power switching power supply with an air core
transformer.
When it gets right down to it, a spark gap is a pretty inexpensive and
decent way to switch high currents at 10s of kV.
> Many thanks,
>
> Greg
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