RE: [TCML] mini Tesla coil specs

["S&JY" <youngs@xxxxxxxxx>]

Herr Zapp,

Here is another possibility for an SCR driven TC:

From: Al Syme <asyme@xxxxxxxxxx>  This is from 1998
To: Tesla list <tesla@xxxxxxxxxx>
Subject: SCR power supply

To All
A while back I ran across a book on induction furnaces. In the book was a
short discussion on using SCR's in a circut like a multivibrator  to
provide power for an induction furnace. The book was vague about the actual
circuitry involved but it did allude to a circuit that (1) provided back
EMF to shut off the SCR and (2) provide a trigger pulse to fire the SCR for
the oppsite polarity. I don't know what the upper frequency limit for tis
type of circut is, but I'm thinking that it may be a way of generating
power at high enough frequency to make it cost effictive for us coilers on
a budget. If any of you have run across this application, any information
would be helpful.....Thanx               Al Syme   KG0QJ

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Quarkster
Sent: Friday, November 06, 2009 10:50 AM
To: Tesla Coil Mailing List
Subject: Re: [TCML] mini Tesla coil specs

Hi Paul -

Since you had also mentioned driving a coil with a SISG switch, I wasn't 
sure if "SRC" might be a new type of power switching circuit that you might 
have discovered somewhere. I suspected that you might have meant SCR, but I 
thought it would be better to ask for clarification.

In some industrial power-control systems, strings of series-connected SCRs 
are used to obtain the high standoff voltage ratings required. Large arrays 
of series-connected high-voltage, high-current SCRs have shown up on eBay 
that have power ratings of hundreds of KW. However, I think these are 
primarily used in pulse-width-modulation power control of resistive loads. 
SCRs typically have rather slow turn-on and turn-off characteristics, 
compared to IGBTs or MOSFETs, so they are not optimum for any application 
that requires high-frequency switching.

Over the years, there has been a fair amount of discussion on the TCML 
concerning the use of SCRs as switches in Tesla coil primary circuits 
(search the TCML archives at www.pupman.com). However, I don't recall anyone

ever actually building a SCR-commutated Tesla coil. (If anyone is aware of a

Tesla coil that successfully used SCRs as a primary switch, please speak 
up!)

SCRs are used very successfully to drive high-voltage generators based on 
iron-core automotive ignition coils, but this is quite different than a 
resonant Tesla coil.

Regards,
Herr Zapp


----- Original Message ----- 
From: "Paul Brodie" <pbbrodie@xxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Thursday, November 05, 2009 9:40 PM
Subject: Re: [TCML] mini Tesla coil specs


> Sorry, Herr Zap.
> Simply a typographical error. I am legally blind and I normally write with

> 18 type size. It is very difficult for me to see what is on the screen 
> when I write with small type like this. I have set it to do it 
> automatically when I write with HTML. Please excuse the error. By the way,

> even though I am using plain text, is there any reason I can't use a 
> larger type size when writing to the TCML? I suppose I should be asking 
> Chip but in a way, I am. ;-)
> Thanks for pointing out the error. That made my question rather confusing,

> I suppose.
> Paul
> Think Positive
 


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