Caps

Homemade capacitor page.

MMC's are the way to go.
It dosen't hurt to spray the board with silicon conformal coating.

MMC Caps - The only way to go if you don't have commercial caps.

Panasonic caps 1600 VDC
Each cap = .056uf
Each row of 12 = .0046uf
4 rows = .018uf
Leave space between caps.

Obvious dammage to several caps, with no apparent degradation in performance.
The advantage of self healing properties can't be overestimated.

Back side of the PC board.
Always put the bleed resistors on the back side of the board.
These are normal 10 MEG 1/2 watt resistors.

Plate Caps

Old tab style plate cap I don't recommend tab style plates, way to much hassle to make. Check below.
Update:All the failures were due to flashing around the dielectric sheets. I have had good success with 6 mil Poly sheet. Cut in strips and wrapped around the plates. The cap in photo below has 96 mils of poly between plates.
I just wrapped each plate with a 10' strip of poly. Use a bit of masking tape to hold it together. Since the poly is continuos, there is little danger of flash over at the ends of the plate. The top and bottom had 1.5" extra to guard against flash over. The best part about wrapping the plates is that it all stays together, and aligns easily. Mine ended up with 7 layers on one side and 8 on the other. When the plates are stacked there was 15 layers of 6 mil poly between each plate. With this method it is important that the cap be squeezed down the minimize the space between layers. This will increase the capacitance greatly. Since the boxes I made fit the caps tightly, it was sort of self squeezing.

Wrapped plates are much easier to make.

New Plate Caps

These plate caps use an extended foil design similar to rolled caps. All the plates are compressed between the buss bars for an excellent connection. And much easier to make than tab style plates.
To make the foil plates, cut a template out of heavy card stock (manilla folder). Then fold the aluminum foil around the template, keeping wrinkles to a minimum. It's easy to get no wrinkles at all. Fold under all edges so no cut edges protrude except at the tab end. Then slide the template out. With a little practice one can quickly make some very smooth 2 layer foil plates with folded under edges.
There is .096" of poly between layers. The plates allow 1.5" edge space at the top and bottom and 2" space at the end where the foils extend.

Here are a couple of plate caps and their intended home. Total capacitance is .011uf.
I wanted compact strong cap containers, so I made some. This one is 12" long X 6" wide X 12" high. The wood box is generously coated with polyurethane resin and reinforced with fiberglass. It is made to fit in a plastic milk crate There is a spacer of 1/2" polyethylene cutting board in the bottom as well as generous extra poly along the sides.
This cap only took 32 ounces of mineral oil to fill.
The new boxes are made of 3/16" masonite. Glued together with " Elmers Pro Bond " polyurethane glue. With no other reinforcement they are very strong. The masonite doesn't absorb as much polyurethane coating.

Rolled Caps These offer more capacitance in a smaller package. However they are much to much hassle to make.
I had better luck rolling shorter(5') rolls that fit in 2" pipe. They have 30 mils of poly between plates.2 foil plates. The 3 of these in series(photo above) are .088uf @ 21000v.
Rolling one giant cap was too much hassle. Besides it safer to run more caps in series than one big one. If a cap does blow, a replacement is easy.
Rolled caps with glued on ends are not repairable. Not that you would be able to repair it anyway.