The MMC (Multi-Mini Capacitor) board is designed for use with CDE940C series polypropylene pulse capacitors and works with all thicknesses of the 940Cs available. This is the most well known and used capacitor type for Tesla coil designs. It can be used with SGTCs, DRSSTCs, other high power resonant LC designs, or anything else that requires an MMC. The board itself has a hole pattern that matches up to a standard 80mm computer fan and ventilation holes allowing the MMC to be air cooled while operating. Multiple PCBs with MMCs can be attached in series or parallel, allowing them to be stacked and expanded to any size MMC desired. The board was initially designed to be mounted to a fan that blows directly on a heatsink with the inverter, making a highly compact and well cooled DRSSTC system.

My DRSSTC 1.2 uses a 4X4 MMC using two 4P2S boards and has successfully fun up to 1000Apk with this configuration and routinely runs >600Apk at long pulse durations and high BPS and stays very cool. Check out the WaskaLabs Instagram to see the board in use.

To use the board, solder the capacitors as seen in the diagram. Balancing resistors can be used if desired by soldering them in series with each capacitor. Attach the board to the fan using a plastic M4 screw and plastic standoffs. The board can be quite close to the fan, but ~5-10mm or so is advisable. For stacking multiple MMCs, you can use longer M4 screws and standoffs and stack to desired size. If the MMC uses an odd number of caps that don't fit on the MMC PCB evenly, partial boards or jumpers can be used to make the MMC the proper size. The connection side of the board has multiple connection holes, all sized to be able to fit a 1/4" or M6 brass screw through as a high current connection. These holes are designed for use with large aluminum lug terminals (Available at Home Depot or other local hardware stores) for a simple connection to the primary circuit.

The PCBs come in 4P2S and 2P4S (P = parallel, S = series). To spec the MMC for your design, check out the CDE940C datasheet for an overview of capacitor options and ratings. An easy way to calculate the capacitor for a DRSSTC application is to use the the web based Kaizer MMC calculator.