[Prev][Next][Index][Thread]
Re: Capacitors
----- Begin Included Message -----
>From tesla-at-poodle.pupman-dot-com Sat Sep 21 20:18:51 1996
X-Authentication-Warning: poodle.pupman-dot-com: bin set sender to tesla using -f
Date: Sat, 21 Sep 1996 12:25:32 -0600
From: Tesla List <tesla-at-poodle.pupman-dot-com>
To: Tesla-list-subscribers-at-poodle.pupman-dot-com
Subject: Re: Capacitors
>Subject: Re: Capacitors
Reply-To: tesla-at-pupman-dot-com
Comment: Now running Red Hat 3.0.3 Picasso
Content-Length: 1423
>From jim.fosse-at-bdt-dot-comSat Sep 21 11:51:35 1996
Date: Fri, 20 Sep 1996 05:19:36 GMT
From: Jim Fosse <jim.fosse-at-bdt-dot-com>
To: tesla-at-pupman-dot-com
Subject: Re: Capacitors
>From: Julian Green <julian-at-kbss.bt.co.uk>
>To: tesla-at-pupman-dot-com
>Subject: Re: Capacitors
>
>Jim,
>
>My cap is made from 4 sheets of 10 mil each poly sheet and takes 10Kv directly
>from the neons. Voltage must be highter than this when used in a TC tank.
>Don't know how much higher. The poly in my cap does not glow. I would have
>noticed this when running my cap dry.
>
Oops, I'm sorry if I gave the impression that my poly glowed. I was
asking RH if a glow COULD be seen just before the cap broke down.
If that was the case, I would surely look for it with my next cap.
>Now that you have commented about your caps glowing, I am thinking that curtain
>types of poly glow in an electric field. The poly that I have looks, feels
>and smells top quality. It is exactly 10mil thick and blue. I am sorry I have
>no more info on it as my father aquired it following a road accident where a
>lorry shed its load. The driver was only too pleased for my father to clean
>up the mess as the police had not yet arrived.
Oh well, I would have loved to know the source.
>
I've not been able to roll 3 layers of 6mil poly, the stuff is just to
darned slippery. Is you cap of a flat plate design? If it is rolled,
what is your secret;)?
cheers,
jim
----- End Included Message -----
It sounds like I have aquired the skill of rolling caps with out knowing it.
Before I started with TCs I used to make fireworks. Lots of tube rolling is
necessary with wet pasted paper which is also slippery, not to mention sticky!
Getting the tube off the former was my bigest headache.
I have two methods. Method No 1 when you dot't have much space. Method No 2
if you have a 3m long table.
Method 1
--------
First roll the poly sheet up.
Roll it around something fairly heavy. I use paper tubes (I have plenty from
my previous occupation).
Sit down at a clean table. Dump a heavy object on the table about 1m away,
then taking the first roll of poly lay on the table and allow it to unroll
away from you. The heavy object will stop it unrolling too far. Repeat for
the other three rolls of poly. Do the foil in the same manner. More poly
x4 and the other sheet of foil. Align the edges, this is much easier now
as you have no more than 1m unrolled.
Take a length of plastic pipe and start rolling your cap around the pipe.
Have plenty of spare length of pipe to act as handles. Take your time.
Turn the pipe rather than rolling it (not to start with). After a couple of
turns the poly will tighten and grip the pipe. If the layers of poly become
mis-aligned the rolls in front of you will reflect this. You need to back
track until alignment is regained. Be very fussy with roll alignment, a small
error at the start is a big error at the end. Do not force the plasic sheet or
foil it will crease. Generally you can not correct a missaligned roll without
back tracking.
Having rolled your cap small adjustments can be made by back turning the roll
to loosen and sliding to get near perfect alignment.
The diameter of the tubes you roll the final cap around can also help. First
time you roll the cap roll around 3" tube. Leave the poly to settle for a
week then roll around a smaller tube.
Method 2
--------
I booked a meeting room here at work where there is a very long
table. Layed the poly and foil out flat on the table. Made sure that all
the poly sheets were free to slide. Layed the poly and foil to make the cap
then simply rolled it up. True the poly sheets do slide, but with the help of
a friend and carefull rolling I managed to keep them in line. After rolling,
the ends of the poly have formed a 'stepped' end. This does not matter as I
know I left plenty of border to prevent flash over.
Roll the cap around a tube. Turn the ends of the tube to roll the cap. This
will help prevent slipping.
The overlapping foil area is 0.3m by 2.5m with 4x10mil poly sheets between the
plates making a cap of value 0.03uF. The final cap will be vacuum impregnated
with transformer oil and used in parallel/series configuration.
Each cap not to exceed 10KV. Richard Hulls recomendation to prevent oil
ionization.
Hope this helps
Julian Green.