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MMC from Microwave Caps
Original poster: "Kelly & Phillipa Williams" <kellyw-at-ihug.co.nz>
Hi All,
I had an idea for a cheap 'MMC' using microwave capacitors.
The capacitors are 1 uF, (1 E -6 Farads)
If I put 20 caps in series, (one string)
the voltage rating would be a whopping 40 kV *RMS* or 56 kV DC!!
(Assuming the faceplate voltage of 2000 VAC)
The capacitance would be 50 nF (0.05 uF)
At first glance, this seems like a great MMC, but there are a couple of
problems I have
thought of.
1) I remember someone telling the list that these caps have small internal
leads and thin
plates, perhaps limiting their current discharging capability
2) Their dv/dt (Volts per microsecond) may not be high enough for TC use
3) Due to tolerances, the voltage stress on each cap may be unequal, leading
to early failure.
(although the voltage rating of the whole cap is very high)
4) One string of caps may not be able to handle the current stresses
I have 23 microwave capacitors.
I'd really like to be able to do this, (as it's free,) and I'm desperate for
a cap for first light
so I can spend some time thinking about what I want to buy for a more
traditional MMC,
as it will cost me quite a lot of money (for a student).
*Does anyone know of any problems with this idea, or can confirm my
thoughts?*
I don't care if the caps die in a few hours, I got them free.
Thank you very much,
Alan Williams