Advanced Spark Gap Technology
I have been experementing with spark gaps. I made several paper funnels to
reduce the area of a box fan and increase the air velocity. I reduced a 4"
box fan down to 3", 2", 1.75", 1.5" and I checked the air velocity with the
air flow meter that I borrowed from work.
I built a spark gap using 10 flat copper plates 2" x 2" each. The copper
plates are made from roofing flashing from the lumber yard. I cut the
plates with tin snips and filed the edges smooth. I clamped all the plates
together in a stack and drilled a .150 diameter hole threw the entire stack
of plates in each corner. 4 places.
I flattened each copper plate by placing it between 2 blocks of steel 1"
thick 2" square and hitting it with a 2 pound hammer.
I used 2 paper punches to punch out some .006 mil polyethylene flat washers
with a .150 diameter hole in the center. 4 washers in a stack gives me a
.024 space between each plate. I put spacers on all 4 corners. Its all held
together with 4 plastic screws with plastic hex nuts on each corner.
The finished spark gap is about 1/2" thick 2" square with a wire soldered on
each outside plate. The spark gap is taped to the end of a paper funnel and
the funnel is taped to the end of a box fan.
I ran this for about 20 minutes on a 750 watt coil and it works better than
my RQ gap with the same box fan. The flat copper plates act like a radiator
and keep the spark gap cool. The air tends to blow most of the sparks to
the back half of copper plates.
Its small, compact and easy to build. I think it would be easier to build
if the plates were made out of thicker metal so they won't need to be
flattened. Some 1/16" aluminum plates will probably work fine. Wires can
be attached to stake on terminals and put under the head of the plactic
screw on one plate and another terminal under the hex nut on the other plate.
I got the platic screws and nuts at Home Depot lumber yard.