Giant Rolled Capacitors
Note: These have been rendered obsolete and I now use EMMC's exclusively.
The tanks are made of 6" SDR35 PVC, 18" tall. I've glued
1"
spacers in the end caps to keep the capacitor roll off the bottom.
The top covers are 3/8" Lexan with 1/4-20 binding posts. I've
also included Schrader valves for evacuating the air and filling
the units with oil.
The configuration will be four caps in a series/parallel
arrangement to get the breakdown voltage I want. I'm planning on
a total capacitance of .042ufd.
I have an aluminum plate, then six pieces of 6 mil poly, another
aluminum
plate, then six more pieces of 6 mil poly. The buses are 1" aluminum strips attached
to the plates with #10 screws. These screws were then smoothed and covered with a
layer of silicone to help prevent punctures in the poly.
We took a piece of 1" PVC, slit it lengthwise, then used it to hold and roll the plates. You can see it at the bottom of the picture.
Here is how it looked after rolling and securing with large wire ties. NOTE: Rolling this beast was definitely a two or more person operation. Thanks to my wife all four capacitors rolled tightly and performed as expected.
I used my "Mighty Vac" hand pump to pull a vacuum. On the
first capacitor
I broke the bottom of the case when I pulled over 20" of vacuum. Next
time I'll strengthen the SDR end cap by adding a Lexan disk before gluing it onto the PVC
pipe. Remember:Test your containers integrity early on!
The filling process was quite simple. First pull a vacuum then let the oil (Shell Diala-AX) drip slowly back into the tank. Make sure you allowing plenty of time for it to wick up between the poly sheets and plates.
I've retired them after many hours of good service (they are
looking for a good home)...