Re: Ceramic Standoffs

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <MShock8073-at-aol-dot-com>

In a message dated 9/8/01 12:13:39 AM Eastern Daylight Time, tesla-at-pupman-dot-com 
writes: 


>
> > >Hi, All; 
> > > 
> > >Does anyone know of a comparatively cheap source of small, ceramic 
> > >insulation cones? 
> > > 
> > >Thanks. 



Back when I was in this hobby "blind" so to speak (before I found the list), 
I needed one of these standoffs to complete a small coil design I got from 
Radio Electronics magazine. I was trying to stay close to their design. I was 
amazed at the difficulty of obtaining these things. And it seemed that almost 
every search turned up some reference to a manufacturer that would be glad to 
"build to my specs" that is if I needed 10,000 pieces or so! I had driven 
down to Atlanta one day to pick up some parts and got a new catalog from the 
industrial electronics supply company I was doing business with. After 
driving the hundred plus miles back home, I noticed in the catalog the exact 
piece I was needing. DOH! If I had only thumbed through the catalog while I 
was standing at the parts counter! 

The ceramic insulators that have a conductor all the way through are called 
"pass through bushings" and are designed to pass HV through cabinets and 
such. They are like the bushings on Neon Sign Transformers. There is 2 pieces 
that have a shoulder and mating recess that keeps the HV from jumping to the 
metal case. There is a cork or rubber washer for protecting the ceramic from 
over tightening "too a degree" and they look really nice. The small one I 
picked is smooth sided as opposed to stepped which of course gives me a 
little shorter leakage path but at only 5/8 inches tall, I thought it made 
little difference. Plus I was mounting on PVC anyway. The standoff is mostly 
cosmetic in my application. They are about 1inch long overall and just shy of 
3/4" in diameter. The distance from the case to the top of the cone is about 
5/8" and is a DABURN model number 10-58-C. I bought mine from Ack Electronics 
in Atlanta. They are on the web at www.acksupply-dot-com and the pass through 
insulators are listed in my catalog as 5/8", 1" and 4.5". The catalog number 
on these little ones is "#10-58" and I have not got a current price. The Ack 
people are real nice to do business with. They also have a toll free line 
which I believe can be found on the web site. They list all kinds of stuff in 
their catalog from transmitting tubes, plate transformers and variacs to 
doorknob caps and motor run caps to triacs rated at 40A and 800V and SCRs 
rated 500A at 1200V WOW!  A couple of those back to back would make the heart 
of a really serious dimmer circuit for a trigger gap! 

Hope that helps. 

Marc S.