Note - much better picture on the way!!!
Tesla Coil Capacitors
Multi-Mini-Capacitor "MMC"
(abbreviation MMC was conceived by Reinhard
Buchner of TCML fame)
I just finished my 1st MMC. I managed to test it out right before Christmas 99. It kicks ass! The little fellow performed just as well as the old rolled LDPE units. I will never go back to big, oily capacitors.
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This pic shows 4 modules that are 10nF (.010uF) each. Each module is rated at about 16.5KVDC. Although the manufacturer says that we should derate the max AC voltage to about half of the DC max, other coilers have demonstrated excellent reliability running these guys at NST and PT voltages. |
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This photo shows the 1/2 watt, 10 meg ohm bleeder resistors across every capacitor. |
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Pic showing most of my new tank
circuit. Shown is a TCBOR gap, enhanced NST, PFC cap for the NST,
and MMC cap.
Note - much better picture on the way!!! |
Here are other great sources of MMC informantion:
Terry Fritz's MMC Power Handling Calculations
This a great letter that Terry Fritz posted to the TCML on 5/14/00:
Hi All,
I have been looking over my MMC cap testing and it looks like the WIMA FKP1 series and the Phillips 376 series are the best. One could probably go to 0.1uF or higher values of these caps in the 1600 to 2000 volt range. The GE 42L series looks good too but I think there is an issue with their lead connections not being able to take very high current pulses??
WIMA FKP1 1600V 0.01uF 3 amps 375kHz 6.8 Deg. C
Panasonic 1600V 0.056uF 3 amps 373kHz 3.4 Deg. C
PHILLIPS 367 KP/MMKP 0.0047uF 2000V 1 amp 375kHz 9.4 Deg. C
GE 42L32222 0.22uF 2000V 3 amps 370 kHz 1.47 Deg. C
FCI 0.015uF 6.5kVDC 1 amp 370kHz 5.15 Deg. C
Sprage 430P 0.22uF 4000VDC 3 amps 370kHz 5.3 Deg. C
Arcotronics "RS" 47nF 1500V 2.5 amps 350kHz 2.2 Deg. C
Phillips 56nF 1600V 3.5 amps 350kHz 1.5 Deg. C
If I calculate the heating for all as a standard
10nF 3amps 370kHz case:
WIMA FKP1 6.8 Deg. C (medium size polypropylene)
Panasonic 19.04 Deg. C (medium size polypropylene) (old test)
Panasonic 19.74 Deg. C (new test)
PHILLIPS 367 KP/MMKP 39.76 Deg. C (4.7nF version small poly cap)*
GE 42L32222 3.23 Deg. C (big cap but must be polypropylene)
FCI 0.015uF 69.52 Deg. C (big cap so probably polyester)
Sprage 430P 116.6 Deg. C (big cap so probably polyester)
Arcotronics 14.9 Deg. C (Smaller tubular poly caps)
Phillips 6.17 Deg. C (56nF version)
Cheers, Terry
Polyethylene Pulse Discharge Capacitor
These things were a lot of work. By the time you purchase all the materials you will spend around $50-60 dollars per capacitor. You can build a much smaller, lighter, repairable, and cost efficient capacitor by taking the MMC route.
I used the basic procedure laid out in the Tc-plans.zip to build these rolled LDPE capacitors. Again, all pics are "clickable".
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Ooops, there is an error on this photo. It should read (2) at .018uf instead of .027! |
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Picture of the vacuum pump, capacitor, and 5 gal bucket of Shell Diala-AX
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Here you can see the raw materials for (2) .019uF caps. Note the LDPE, it's about the same color as the floor. |