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Re: MMC caps



Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 03:44 AM 3/16/2006, you wrote:
Original poster: "R. Amaya" <dimon20042004@xxxxxxxxx>

Hi all,
I am wanting to build an MMC with a rated capacitance of 80-90nf and around 50kv and I will be feeding it 16,000 vac at around 500ma. Can anyone tell me what would be a good MMC cap for this job?
Thanks in advance,

How brave are you? You could string together 25 capacitors, each 2kV and 0.15 uF, which would make a 6 nF string. Then put 15 strings in parallel. That's 300+ caps. You're getting up into the price range where a suitable pulse discharge capacitor from Maxwell might be a better deal (a bit more cash, many fewer hours soldering).

Or, you could be brave and run those 2kV caps at, say, 4kV, so you'd string up 12 in a row for 48kV, and then you'd only need 7 strings in parallel.

Something else you need to know is the RF current. What's the inductance of the primary? You can then ball park the peak RF current by 1/2LI^2 = 1/2CV^2

 Robert