Re: Condenser Products capacitor performance
Subject: Re: Condenser Products capacitor performance
Date: Tue, 6 Feb 1996 17:09:20 -0500
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In a message dated 96-02-06 14:15:12 EST, you write:
>After reading the following excerpt from a recent post, I thought I would
>give a report on the
>first firing of my new .025 uF, 20 KV RMS commercial pulse discharge
>capacitors. The initial
>tests were outstanding.
>> ........I just finished blowing 2 caps in my TC primary last
>> night. I'd found some surplus 0.015uF 6.5KV DC film caps for $.99 each. I
>> bought 10, wired 9 in series/parallel to get 0.015uF at 19.5KV. I was
>> running about 6KV into the primary of my TC so I figured that a 3:1
>> margin was ok. WRONG! Both times that I approached resonance, beautifull
>> little sparks started showing thru the case of the caps......
>> .....I'm still argueing with myself over wether to build a oil and
>> film cap or to order one from Condenser Products.
>> I can tell you though, don't was your time with doorknob caps and 14 gage
>> primaries! 4" sparks vs. 12" with dc rated caps and 1/4 copper tubeing
>> primary. I can't wait to see what length sparks I'll get with a real pulse
>> rated cap.
>Secondary - 6" diameter on acrylic form with 943 turns of 22 gauge wire
> for a winding length of 26.5", sealed with epoxy
>Primary - 13 turns of .25" copper tube on a 20 degree inverted conical
>Final Toroid - 28" diameter homemade with a 5" cross section
>Spark gaps - 6 series copper pipes 3" long with vacuum motor quenching,
> gapped at .0045"
>Transformer power - Neons, 15,000 VAC with 90 mA total current (1.35 KVA)
>Setup - It consisted of using a balance primary with the capacitors on
>opposite sides of the
>secondary for a total capacitance of .0125 uF. The spark gaps were across
>the capacitors. I
>took care to keep off-axis inductance to a minimum. There is less than 2'
>from each side of the
>primary back to the spark gaps, including the length of the capacitor. A
>arrangement was used, .0009 uF and 2.2 mH was used per leg of the
>in the filter. A
>safety gap was in place. The RF grounding system consists of (5) 10' x 5.8"
>copper clad rods
>spaced 9' apart. They are connected to one another via 2.125" wide solid
>copper strap that has
>been soldered to the tops of each rod and buried along with the rods.
>Another identical copper
>strap is soldered to this and connects the base of the coil via a connecting
>plate on the
>secondary, per RQ's design.
>After making several runs with smaller toroids and trying different coupling
>heights, I have
>gotten as much as 4.5' discharges to a ground point. The free-air streamers
>are about 4'. I am
>tuned all the way out to the end of the 13 turns of the primary. I need to
>make a larger toroid
>to see if this can be improved without the addition of more power. Based on
>experiences and others observations, the efficiency seems very high. It
>calculates out to 300 VA
>per foot of spark. I suspect I am at or very near the maximum discharge
>length for this level of
>input power. I was pleasantly surprized by the results of this preliminary
>set-up. I would
>guess that I am approaching the level of diminishing returns on this size
>coil. I will add more
>power at a later date, as I have to move some items in my garage to allow
>longer free air sparks.
>After going to a larger toroid, I will need to either add more turns on the
>primary, or drop out
>one of the capacitors. I will initially drop out a capacitor, as this is
>easier thing to do.
> I will no doubt lose some efficiency by doing this. I will post the
>of both adding
>turns and increasing capacitance. I will not be able to get to this
>experimentation for about a
>week, as I have to leave on business.
Sounds like a good project. Nice sparks. Keep us posted. I know about
diminishing returns. I have a coil about the same size, using one .025
Condenser Products cap, I think I got about 4.0 foot discharges with 1.5 kva
in. Now with a pole pig and 6 to 8kva in, I only get 6.0 foot discharges. I
think I have reached the physical limitations of this system. Still fun