Re: bargain or dead bird? (fwd)
---------- Forwarded message ----------
Date: Mon, 19 Jan 1998 16:45:04 EST
From: Esondrmn <Esondrmn-at-aol-dot-com>
Subject: Re: bargain or dead bird? (fwd)
In a message dated 98-01-18 11:45:21 EST, you write:
<< Before starting to build my own rolled caps, i thought of using plastic
picnicplates as isolation between the aluminiumsheets used in the
kitchen (is this what they call 'flashing alu' ???). For higher voltage
or after a breakdown only adding or replacing plates is needed. The caps
are easily made and stackable to higher values.
1) HAS ANYBODY EXPERIENCE WITH THESE CAPFORMS??
I have not used these materials. Aluminum flashing is flat, rolled aluminum
sheet usually sold in 14" width rolls 10 feet long. Available at building
I was offered tens of NST 8000 V varying from 30-50 mA for 13 U$ each
only. What about cascading them for higher voltage and switching them in
parallel for higher current? Also somenone offered me a transformer with
variac (!) with 7000V/ 700mA output including a vacuumpomp for 400 U$.
Sounded very attractive but what is more important for getting long
2)HIGH VOLTAGE OR HIGH CURRENT?
You really can't connect neon sign transformer secondaries in series. They do
not have enough insulation to the case (or to the core) to stand this. If you
unpot them and submerge them in oil, it may work. I have heard of folks doing
this with microwave oven transformers successfully. The best bet with NSTs is
to find a few of the highest voltage you can get (the voltage rating must be
the same for each) and use them in parallel to boost the current capacity.
The primaries can be used either in series or parallel.
This big transformer needs a cap(prim) of about 0.32 uF.
3)DO THESE BIG VALUES FOR CAPS REQUIERE SPECIAL ACTIONS OR GIVE CERTAIN
The biggest problem I see would be the cost. This would be a very expensive
cap. You could certainly use the 700 ma transformer with a smaller cap. This
sounds like a potential transformer, or heavy plate transformer. Too bad it
isn't 10 kv or 12 kv. The price is not bad including a variac but 7000v is a
little low for a spark gap excited Tesla coil primary.
Isn't it so that when firing a coil in different place with different
max. poweroutput of the partcular walloutlet and thus different settings
of the variac->
4)THE CAPS and GAPS ALWAYS SHOULD BE READJUSTED WITH DIFF.
Once the primary and secondary are adjusted to be in tune, you should be able
to move the coil from site to site and use the same primary tap position.
Changing the variac setting will not change the tune, except with a high power
coil with a large toroid, the frequency will drop a little going from lower
power to high power due to accumulated charge around the toroid causing it to
appear larger than it really is.
the static gaps described as build up with pvc tubes: are they just a
PVC tube with several pieces of copper tubing stack up in a row through
the pvc tube and
5)ONLY USE THE FIRST AND THE LAST PIECE OF COPPER TO CONNECT THE GAP?
As you look down from the top, the copper pipe sections are arranged in a row
as you go around on the inside of the pvc pipe. When you make these, you want
to leave the brass or copper bolts long enough so you can make connections to
any individual section so you can adjust how many gaps you are using.
6) AND IS THE ALWAYS DESCRIBED FAN JUST BLOWING THROUGH THE PIPE TO
Yes. Because of the low speed and volume of air, I think it mostly provides
cooling for the copper pipe sections - which would help quenching.
7) CAN I SIMPLE ADJUST GAPLENGTH BY CONNECTING 1 SIDE OF THE GAP TO THE
FIRSTLAST OR SECONDLAST (ETC) COPPERPIECE?
Good luck Sparky, Ed Sonderman
Waiting for answers, chears Sparky