[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [TCML] Gaps
Bart,
I sure hope that you are correct about the browning
being from overheating and not from UV exposure.
It was in one of my previous stationary gap designs
from several years ago that I noticed this "browning"
of the PVC. I can't seem to remember a lot about the
details of the construction but I do remember the PVC
browning and even starting to flash over. I had assumed
that it was due to UV exposure but it could have been
just due to overheating of the electrodes that were in
contact with the PVC. I'm just guessing on the CFM of
my cooling fan on my current design. It's a Comair Rotron
"Tarzan" 59 watt, 120 volt, 6", electric fan, but I can't lo-
cate a CFM rating on it. It seems to move a good deal of
airflow, though.
David
----- Original Message -----
From: "bartb" <bartb@xxxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Saturday, February 23, 2008 10:06 PM
Subject: Re: [TCML] Gaps
Hi David,
I've never had an electrode fail due to the epoxy getting hot, but that
is likely due to ensuring the electrodes themselves stay as cool as
possible under the conditions. I'm not sure what would happen if I were
to turn off the airflow (and I'm not about to try it). If the electrodes
get hot enough, there's probably a good chance epoxy will become
flexible. Don't allow that by ensuring the electrodes stay cool under
normal operating conditions. Sounds like you have a good deal of cfm, so
chances are your gap will do well. If you get any "browning" of the pvc,
the electrodes are running too hot. More airflow is absolutely required
(much more).
Take care,
Bart
David Rieben wrote:
Hi Bart, all,
I've often wondered how well that glue
could hold up under the heat and UV radia-
tion over time without significant degridation.
As fas as that goes, I've seen the PVC itself
gradually "brown over" and actually start be-
coming a bit conductive due to the bombard-
ment of UVs from the SG plasma. On my
latest SG driven coil project, I have have
just cut 2 slits in the 6" diameter mounting
PVC pipe and mounted the 1" diameter x
5" long copper tube electrodes (8 of 'em)
to the PVC pipe via the slits with 1/4" x 20
TPI machine screws (and nuts). I think I
saw this idea on someone else's website
but I can't recall where. This does away
with the problem of not being able to pre-
cisely locate the mounting holes for those
of us who do not have access to fine machine
shop facilites and makes for a pretty well infi-
nitely adjustable RQ gap. I simply tighten one
copper tube, trying to insure it's parallel with the
PVC mounting pipe and then slide the next tube
up next to it, using the thickness of a credit card
to space the individual gap. Seven seriesed gaps
of this caliber allow my 14.4 kV PT to just break
down the gap at about the rated 14.4 kV applied
to the gap assembly. I have yet to fire it through
the tank circuit capacitor as I am still waiting to get
one of those bulk buy 6 x 24 spun aluminum toroids
that DC is supposed to be working up next month.
Besides that and driving in a good grounding rod
for RF grounding it, everything else is ready to go!
O yes, I fogot to mention that I am using a ~300
to 400 CFM fan for the forced air cooling of the
SG tubes.
David Rieben
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla