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Re: Plastic Cap Capacitors

Subject:  Re: Plastic Cap Capacitors
  Date:   Mon, 21 Apr 1997 11:25:29 +0200
  From:   tesla <tesla-at-ixx.se>
    To:   Tesla List <tesla-at-pupman-dot-com>


At 16:19 1997-04-20 -0500, you wrote: 
>Subject: Plastic Cap Capacitors 
> Date: Sun, 20 Apr 1997 10:24:04 -0700 
> From: Bert Hickman <bert.hickman-at-aquila-dot-com> 
>Organization: Stoneridge Engineering 
> To: tesla-at-poodle.pupman-dot-com 
> 
> 
>All, 
> 

>David Flinn came over last night to show me his smaller coil powered 
>from a pair of open frame Actown neons. The tank cap he used was a small 
>rectangular plastic-cased capacitor from Plastic Capacitors, rated at 
>7500 VAC, and the coil was powered by some really sharp-looking band new 
>Actown open-frame 7.5 KV 30 MA transformers, each with a single 
>epoxy-encapsulated secondary winding. Both ends of the secondary winding 
>were isolated from the transformer core. The unit used a set of six 1 
>1/4" x 6" water-filled copper pipes as spark gaps, with a total gap 
>setting of about 0.100". The secondary was a short (20"?) 6.5" diameter 
>coil, and the primary was short (2" high, 12" diameter) helical coil 
>wound from 6 or 8 gauge THHN house wire. The entire assembly was mounted 
>on an oak base - all in all a very nice looking small coil!! 
> 
>David also brought over a larger .01 uF 15 KV Cap from Plastic 
>Capacitors in order that we could do a "stress test" in my larger 
>system. Plastic Capacitors rates their units similarly to Condensor 
>Products (CP) - Input RMS for Tesla Coil use - and this particular unit 
>costs about $180. Plastic Capacitors uses a number of internal and 
>external construction techniques that differ from CP in order to get a 
>pulse cap which, they claim, is more robust. The case appears to be 
>fabricated from a phenolic material and is rectangular in shape, roughly 
>1.5" x 4" x 12". The unit is filled with silicone capacitor oil, and its 
>construction apparently permits thermal expansion without excessive 
>internal pressure build-up. Polypropylene film is used as the 
>dielectric. 
> 
>The last commercial capacitor we tried on this system was a CP 0.025 uF 
>20 KV CP cap that Don Froula brought over last October. This particular 
>unit failed, fairly explosively, blowing off one end and physically 
>ejecting oil and one of the internal capaitor rolls. A subsequent 
>failure-mode analysis by CP indicated that this unit was part of a batch 
>which had a manufacturing defect, prompting a recall of the batch of 25 
>that were purchased by many in this group last year. This particular 
>unit failed only at about 80% power input to a pair of 15 KV 60 MA, 
>using 13 gaps (7 static, 6 vacuum), at about 400 mils of total gap 
>spacing. 
> 
>In last night's runs, we disconnected one of the two 0.01 uF home-made 
>flat-plate caps and connected the little .01 uf 15 KV Plastic Capacitors 
>unit in parallel with the remaining flat-plate cap. The system tune was 
>left untouched. We then started running at successively higher gap 
>settings and power levels, finally going to full power (18 total gaps - 
>0.54") and 140 VAC input. Coil output and performance was the same, or 
>perhaps somewhat better, with white-hot streamers and solid, loud, 60+" 
>ground hits. Maximum runtimes were kept to about 30 seconds. 
> 
>Results: 
>The little cap took a lickin' and kept on tickin'(!) with absolutely no 
>evidence of internal heating or any other abnormal behavior. The next 
>trial will use two of these units in in parallel. I've got to admit that 
>I was favorably impressed! We'll keep the group posted on any future 
>runs with these units. Chuck Curran sounds like he is getting very close 
>to firing up his new coil using a much larger 0.05 uF 30 KV Plastic 
>Capacitor unit in larger 15" system... hope it works as well as this 
>little unit seemed to on mine! 

Hi Bert. 

Sounds very interesting. Do you have any information regarding PC doing
overseas shipments? CP doesn't do that so it would
be excellent for us not living in the u.s to get our hands on some good
caps. 
Do you or anyone have more detaild info on the pricec, shipment costs
etc. 

//Matt 
---------------------------------------------------- 
Matthias "Tesla" Andersson 
tesla-at-engelholm.se 
http://www.ixx.se/usr/tesla/default.htm 
-"Why am i glowing in the dark?" 
-