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Re: [TCML] Caps

This advice mirrors my (pretty limited) experience. With a Terry filter and properly set safety gaps I never blew an NST. I did blow some caps, but it was because I hadn't sufficiently de-rated them. With properly rated caps I never had a problem. And I did get better performance than a LTR cap bank. Never tried STR. 

Just my 0.02. YMMV.

Jonathan
----- Original Message ----- From: "Futuret" <futuret@xxxxxxx> 
To: <tesla@xxxxxxxxxx>
Sent: Wednesday, August 29, 2012 12:52 PM
Subject: Re: [TCML] Caps
If you're using a static gap with an NST, it should be OK to use any capacitor whether 
STR, resonant, or LTR.  Just don't make the gap too wide.  The gap
if not too wide should clamp the voltage at a safe level.  To get the
most spark length safely from an NST and static gap, it's probably necessary
to use an LTR cap.  STR will work but will give shorter sparks, even when
running at a higher break rate.
If you're using a non-sync (asynch) rotary with NST, then it's best to use an 
STR cap, or be sure to keep the break rate high enough so you don't
start getting large voltage peaks.  Avoid using a resonant cap with an
asynch rotary with NST.

If you use a 120 bps synch rotary with NST, then be sure to use an LTR cap.
The voltage will go too high using a resonant cap.  Even if the cap itself
can withstand the voltage, the NST will likely be destroyed.  They really
don't like excessive voltages. Using the 120 bps synch rotary, a larger LTR cap 
can be tolerated (and benefited from) than when using a static gap.
There's a list of "best" LTR values for static and synch rotary gaps "somewhere" 
on the internet.

The Terry filter and safety gap does a lot to protect an NST, but the
other guidelines above should be followed also to protect the NST.

Cheers,
John
----- Reply message -----From: "Christian Hill" <monolegal@xxxxxxxxx>To: <tesla@xxxxxxxxxx>Subject: [TCML] CapsDate: Wed, Aug 29, 2012 2:22 amHello. I am building my first coil and have a few questions. I read thatyou should stay away from using a resonate sized capacitor as it can causea "condition called resonate rise." Multiple sources say to use a "largerthat resonate" capacitor to keep this from happening. I've read that youcan also use a multiple of the LTR capacitance value as well. Let's saythat the optimum LTR capacitance is 10nF. Since I can double it and use20nF would I also be able to half it and use 5nF? (Assuming that my voltageneeds were met, of course).I would assume that the closer I get to the resonate capacitance value, thebetter chances of resonate rise I have. So I should stay as close aspossible to a multiple of the LTR capacitance, correct? Or should I justmeet my voltage needs, tune the coil accordingly, and make use of safetygaps?I am asking all of these capacitor questions because I want to get the mostout of my money. Those Cornell-Dubillier 942C20P15K-F's can really add upwhen you're on a budget. I tried searching through the archives and havepoured over dozens of tesla coil guides but found nothing that reallyanswered my questions. Thank you very much for your help._______________________________________________Tesla mailing listTesla@xxxxxxxxxxxxxx://www.pupman.com/mailman/listinfo/tesla 






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