RE: [TCML] Tuning idea

[mileswaldron@xxxxxxxxxxx]

Gary,

With a smaller coil you can make a connection onto the primary like a slide connection on a record player arm. While the coil is running and at low power you can move the arm around without killing yourself with sparks, by rotating the primary around and adjusting the arm. I call this "dyanmic tuning" and it is lots of fun to do. I tried one time to add a big high voltage air capacitor to vary the capacitance dynamically and that was pretty interesting too. Big fat arcs started jumping around between the variable capacitor plates until it was destroyed. It worked more like a variable spark gap than anything else, but it was very interesting to observe. There was not enough capacitance to do anything anyway. You can definitely tune a coil by changing the capacitor, and some low voltage coils require that you have to do this. Actually, I saw a guy who had made a glass in oil capacitor who could vary the capacitance by adding and removing pressure from the stack.

Miles

--
<a href=http://www.gravitymagnet.com>gravity magnet</a>

-------------- Original message -------------- 
From: "Lau, Gary" <Gary.Lau@xxxxxx> 

> And to expand on the topic, someone else once suggested a means of continuously 
> varying the primary inductance as a means of tuning. Construct the primary as a 
> flat two-layer coil with a variable separation, with the inner turns of both 
> coils connected with flexible cable and a plastic insulator between them. The 
> combined inductance will be dependant upon the separation between the two coils. 
> Bart has a calculator for this at 
> http://www.classictesla.com/java/2layer/duallayer.html 
> 
> I use a fixed two-layer primary myself for the sake of compactness 
> (http://www.laushaus.com/tesla/primary.htm), but I've not heard of anyone 
> actually extending the mechanics to vary the separation for tuning. But I 
> believe that would be a lot easier than building a huge variable cap. 
> 
> And I've told this story before, but for the benefit of newcomers... I also 
> tried to vary my primary tap, live, to determine the best tap point, by dragging 
> the tap clip across the primary turns. The sparks between the clip and primary 
> were terrifying and I quickly shut down and abandoned that idea. With power 
> off, when I picked up the tap wire to reattach it, I received a substantial jolt 
> from the capacitor. Without the primary connection in place, the normal 
> capacitor discharge path through the NST secondary was lost. I do NOT wish to 
> resurrect the bleeder resistor vs. hard discharge safety thread - just take it 
> for what its worth. 
> 
> Regards, Gary Lau 
> MA, USA 
> 
> > While the idea of live-tuning is attractive, I think that building a variable 
> cap as you 
> > suggest has two problems. First is that it would have to be rather large to 
> achieve 
> > enough capacitance to be useful. Second, a single cap would suffer heavily 
> from 
> > corona. 
> > 
> > Regards, Gary Lau 
> > MA, USA 
> > 
> > > -----Original Message----- 
> > > From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On 
> > > Behalf Of Ben Sneath 
> > > Sent: Tuesday, January 08, 2008 11:57 PM 
> > > To: tesla@xxxxxxxxxx 
> > > Subject: [TCML] Tuning idea 
> > > 
> > > Hi all 
> > > 
> > > ive had an idea about tuning: instead of using a variable 
> > > primary tap, and 
> > > having to cut power change tap position and reapply power 
> > > etc, etc, why not 
> > > use a variable tank capacitance... a high voltage trimmer 
> > > cap coulg be made 
> > > out of any flat sheet material (hard disk platters cut in 
> > > half?) and placed 
> > > in paralell with the tank cap. tuning could be done while 
> > > powered up and 
> > > would be as simple as turning a wheel... you could also keep 
> > > the coil in 
> > > tune as spark length/capacitance to earth increases as arcs 
> > > are drawn off. 
> > > is this a new idea or has some one allready thought of it in 
> > > the past and 
> > > put it in the "couldnt be bothered" corner? 
> > > 
> > > ben 
> 
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