Re: [TCML] dc tesla coil

[jhowson4@xxxxxxxxxxx]

Charles, 
I have been working on a coil like that for a while, but work is at a standstill due to lack of funding for tank capacitors. 

You are correct on the advantage, that you don't need a huge charging inductor which can be substituted for smaller air core units of a few mH. 
But to make it work really well you then need to use a filter capacitor, that way when the charging electrodes align, the tank cap can be charged nearly instantly. As the presentation time for the charging to occur is low. 
The other advantage to this approach is that you can use any spark gap bps you want. even those lower than the mains frequency, but only if you use the filter cap. My filter cap is a large array of microwave caps, it knocks the ripple after the rectifier down to less than 10%. 
You don't need a filter cap, but it really helps if you do, and this drives up costs more than an inductor. unless you acquire loads of microwave caps like i did on the cheap. 

For diodes the 1N5408 works really well in series chains. it has a 300A single impulse capability, and that reduces down to 30A at 400 Hz 3A DC. or so i'm told. 



Cheers, 
John "Jay" Howson IV 


"Why thank you, I will be happy to take those electrons off your hands." 

----- Original Message -----
From: "charles rakes" <crakes29@xxxxxxxxx> 
To: tesla@xxxxxxxxxx 
Sent: Saturday, November 24, 2012 4:46:19 PM 
Subject: [TCML] dc tesla coil 

I've been playing with Tesla coils since 1954 and about 12 years ago had 
started building a medium size coil with abt 1.5kw. I would now like to 
complete the coil. I would like to try making/using a RSG with one set of 
points to charge the tank cap and another set to discharge the cap. If 
this will work I should be able to really simplify the circuit. And not 
need chokes or other protection components. Will this approach work? If 
so I would try using a variable speed bench grinder as the basic of my 
RSG. Any help would be a greatly appreciated. Charles 
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