Kind of old single piece of glass plate capacitor

[304er]

Hi all,

Just would like to share an old school capacitor that my father, brother and me made in the early 1980's that was used on our SGTC also originally built then, which has recently been resurrected as a new/old coil as seen on my thread on Mains Staccato SGTC.

This old capacitor is retired now. Not good any more. I mentioned in the other thread it was quite lossy then. It had corona in constant fingers the whole perimeter on outside edges of metal plates on both sides. Ozone smell from this was quite great. This corona was typically about 3/4" to 1" long... basically a constant purplish growing frame all around plate edges. While this looked cool... hurt coil performance of course. It did work for quite awhile this way. But over time these fingers were actually etching the glass...this was then becoming more conductive...then it reached a breaking point...it started to jump all the way around the glass edges to other metal plate. This itself left arc etching... so it eventually started just popping all the time shorting the capacitor in loud bright white light arc pops...and really killing coil performance. You can see these etches burned in the glass in these pictures.

A few pictures of this fella:

https://photos.app.goo.gl/aUR9tnnWqnnEsKYT7

Just thought I'd share this for those possibly interested in seeing one...from someone who used one in the past...


Chris Reeland
Ladd Illinois USA

[paulj]

I have already come across on youtube a tesla coil made with a glass capacitor which could produce up to 2m of lightning.
here is the link:

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Leyden capacitors with glass bottles containing a brine solution, or else with a thick glass plate separating the conductors have poor reliability. glass has a lot of losses at high frequency, and in addition it requires a lot of space, not to mention its fragility to corona discharges which can lead to a breakdown of the dielectric

Nikola Tesla was aware of the poor electrical insulation of the glass, he replaced the glass with oil as the dielectric, he used this technology on his very large Colorado Springs Coil that everyone knows, he will drop a even a patent:


https://teslauniverse.com/nikola-tesla/patents/us-patent-464667-electrical-condenser

[MRMILSTAR]

I made a very similar glass plate capacitor in the mid-1960s when I attempted to build the "Big TC" Tesla coil from Popular Electronics. I also recall the very cool purple corona around the edges. I didn't know enough at the time that this was a bad thing.

[304er]

"I didn't know enough at the time that this was a bad thing...."


Neither did we...   

And my understanding of Tesla Coil's in general was greatly lacking then...the coil truthfully ran not great...but we were still amazed then...

Thanks for the video link paulj.

Chris

[304er]

Hi paulj,

I was studying the video closer to revive some old memories...

Are we sure this is glass? From what I can see, I do not think it is... looks to be some warping of whatever flat sheet it is...like plastic sheeting does.

No big deal if not really.
Just something I noticed.

Chris

[304er]

Hi paulj,

I fired up my laptop to have a bigger screen vs. my tablet screen.

I got it mistaken...looks to be the RSG shield.

Then I got wondering where is it?  Especially at 56 nF, would need to be large and multiple layers. 

Found it...underneath...quite hidden from view...looks to be glass possibly I think after all.

Nothing in video shows glass or on the text description...but i will take your word for it.

Chris


Update...found in comments section on youtube...builder mentions it as glass...says hard to trust...has me smillin' some.

Update again...found much lower in comments...he says about 50 lbs. the cap! Yikes! But it does make sense when I think about it.

[paulj]

Hi, he has since replaced the glass capacitor with a 100kv maxwell these plates seem very thick, and very fragile.

Many of his videos have disappeared, you could see a lot more details.