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Re: Advanced Spark Gap Technology
to: Gary
At higher power levels G-10 phenolic will work fine. I have a parallel
plate sparkgap using 1/8 inch (0.125) thick copper plates measuring 2.5 x
2.5 inches square. We use two long G-10 strips that are .010 inch thick
(machined very parallel) to space the copper plates. As you mentioned with
forced air, the sparks tend to discharge near the rear of the plates at the
air outlet area. We run the strips approx 85% of the total distance of the
length of the plates so the sparks occur in an area free of the strips.
With only 9 plates (eight sparkgaps) of .010 spacing we have ran at 2.5 kva
for over 15 minutes continuous without any problem from the G-10 phenolic
spacers.
I use some square G-10 1/4 inch thick flat plates that extend well over the
ends of the copper plates and serve as gentle "clamps" to hold the assembly
together. I also smear a mall amount of GE Silicone II on each G-10 spacer
as I put it on the copper plate, and this helps to retain the strips in
position in the event the clamps should loosen during any transport. I use
1/4-20 NC fibre rod (fiberglass material) with 1/4-20 nuts to form the
clamps. The rods go the entire length of the assembly and are on each of
the 4 corners. They also extend downward an additional 2 inches below the
last (lower) plate and go through the lower sub-base assembly of the
oscillator. This allows you to attach them with two locking fibre locking
nuts above and below the sub-base. This holds the sparkgap off the base by
1.5 inches for HV clearance.
I will be drawing up the complete design in late Feb or March for
publication in the TCBA Newsletter.
Regards,
Dr. Resonance
-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Saturday, February 05, 2000 10:08 PM
Subject: Re: Advanced Spark Gap Technology
>Original Poster: gweaver <gweaver-at-earthlink-dot-net>
>
>I ran the spark gap a few times about 1 minute each time then inspected the
>washers. I ran the spark gap 2 minutes then 3 minutes and inspected the
>washers each time. I could see the spark all around the poly washers but
>they never melted or carboned. I ran the spark gap several times over and
>over for about 20 minutes. I am running only 750 watts. If the power is
>increased its possible that heat could be a problem. It would certanly be
>worth expementing to find out. My RQ gap gets hotter when running more
>power so it makes sence this will too. The plates could be made larger
when
>running more power. Larger plates would radiate more heat.
>
>Gary Weaver
>
>
>At 08:24 AM 2/5/00 -0700, you wrote:
>>Original Poster: "Dr. Resonance" <Dr.Resonance-at-next-wave-dot-net>
>>
>>
>>Gary:
>>
>>Doesn't the spark discharge produce enough heat (even with forced air
>>cooling) to start to melt the PE gasket/separators?
>>
>>I made some similar to this once. I used 3/4 inch dia. brass washers and
>>made the insulating spacers of G-10 phenolic which isn't easily effected
by
>>heat from the spark.
>>
>>Regards,
>>
>>Dr. Resonance
>>
>>
>>
>>-----Original Message-----
>>From: Tesla List <tesla-at-pupman-dot-com>
>>To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
>>Date: Friday, February 04, 2000 10:18 PM
>>Subject: Re: Advanced Spark Gap Technology
>>
>>
>>>Original Poster: Dan Kline <ntesla-at-ntesla.csd.sc.edu>
>>>
>>>At 10:32 PM 2/3/00 -0700, you wrote:
>>>>Original Poster: gweaver <gweaver-at-earthlink-dot-net>
>>>>
>>>>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.
>>>
>>>Which one worked the best?
>>>
>>>>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've thought about building gaps like this a lot, especially after
reading
>>>old articles about building quenched gaps and stuff like that, but I
never
>>>could think of a spacer that wouldn't end up either conducting, getting a
>>>carbon track, or breaking from heat-stress. The old designs used mica as
>>>the spacer. But shoot, even if it *did* track, it would be so easy to
>>fix...:)
>>>I think I'll give this a shot. Could you describe the fan/funnel/gap
setup
>>>a little more?
>>>Thanks,
>>>Dan
>>>
>>>>Gary Weaver
>>>
>>>
>>>
>>>
>>
>>
>>
>>
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