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Registered Member #160
Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938
For your NST, resonant charge cap value is 10.6nf. based on 60Hz supply. Using LTR of 1.4 or 1.5 gives 14.8nf or 15.9nf respectively. If you're going to spend a bit of money on MMCs then you want to overvoltage the rating. This is why I say 24Kv.
Registered Member #79
Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673
It's a great meter for the price and is suprisingly accurate.
As far as capacitors, you might try making some stack ones with something like glass or transparancies. This sould be cheaper than an MMC, but alot of people have trouble with stack caps.
For a 15/60 NST and a static spark gap, you want 15.9nF or "close". 10 of the CD 0.15 caps would do fine. There is a chart here to determine such things:
That NST will be a little big for your present coil, so keep the spark gap rather close at first.
Registered Member #50
Joined: Thu Feb 09 2006, 04:07AM
Location: Vernon, B.C, Canada
Posts: 324
Thanks Terry! Now i just have to bite my tounge and press the purchase button. I think digikey has the best deal with the shiiping and all. Now I have to find some 10 M Ohm Resistors. Digikey dosen't sell any rated for 15,000V+...
Registered Member #50
Joined: Thu Feb 09 2006, 04:07AM
Location: Vernon, B.C, Canada
Posts: 324
Got my caps today. I decided to buy from digikey as they "seemed" to have the best deal and for only $8, recieved overnight shipping from the states. Although in my haste I think I may have inadvertently ordered 1/4 watt insteat of 1/2 watt 4M Ohm resistors. Is this going to pose a serious problem? Thanks for all your help terry.
inadvertently ordered 1/4 watt insteat of 1/2 watt 4M Ohm resistors. Is this going to pose a serious problem?
I would use four of them per cap. I run 1M 1/4W at 300V all the time. But I have never tested 4M or 10M 1/4W resistors for real high voltage use. The 1/2 watts are super well proven now.
At 4200VDC it arced over on the outside. Seemed fairly happy at 3000V... So at 2000V peak you should be fine. Seemed the heating at around 3000+V was the biggest problem.
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First MMC
Got my caps today. I decided to buy from digikey as they "seemed" to have the best deal and for only $8, recieved overnight shipping from the states. Although in my haste I think I may have inadvertently ordered 1/4 watt insteat of 1/2 watt 4M Ohm resistors. Is this going to pose a serious problem? Thanks for all your help terry.