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Re: [TCML] Maxwell pulse capacitor


Your pulse cap should have a DC rating that's at least 3X the maximum RMS output voltage of your pole pig. Assuming you're using a transformer that outputs 14.4 kV. If you plan to overdrive your primary to 280 volts from your variac, shoot for 50 kV caps (or higher).

In order to efficiently use the power your pig can deliver, the bang size needs to be fairly large. For example, suppose you want to operate your coil in the range of 10 - 20 kW using a maximum break rate of 240 BPS. Under these conditions, the bang size can be estimated as:

Jmin = 10000/240 ~ 42 joules/bang
Jmax = 20000/240 ~ 84 joules/bang

Assuming your gap breakdown voltage is 18 kV, this means your tank cap size should be about the following:

Cmin = 42*2/(18000^2)  = 0.259 uF
Cmax = 84*2/(18,000^2) = 0.518 uF

As Steve mentioned, the Maxwell 37XXX series have PPS ratings of 500 - 1000 PPS and are the best choice for TC use. Some 31XXX series caps will also run at 100 - 400 BPS, such as 31393, 31507, 31662, 31677, 31687, 31892, and 31981(all 100 PPS), and 31583(400 PPS). I would NOT recommend using any caps rated for 1 PPS, since they can overheat and quickly self-destruct from internal heating before the outer case even has a chance to get warm.

You can play with the above calculations above to see what works best for your planned system.

Good luck and best wishes,


Tyler LaVite wrote:
I’m buying a maxwell pulse capacitor for my 25kva pole pig. Couple options here which is the best one to buy these are what’s available.

125uF @ 40kv
.25uF @ 50kv
.118uF @ 100kv
.101uF @ 40kv
5.4uF @ 20kv
.252uF @ 50kv
.251uF @ 50kv

What are your guys thoughts on the best one for just messing around no specific use maybe possibly use it in a larger Tesla coil then my current one this summer.

Sent from my iPhone
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