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Re: Carrying a Full Load (fwd)



---------- Forwarded message ----------
Date: Sat, 1 Aug 1998 14:31:50 -0600
From: terryf-at-verinet-dot-com
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Carrying a Full Load (fwd)

Hi Dave,
        I have a old bug zapper transformer similar to what you describe.  I
have never used it for a TC but I would like to some day.  Further comments
follow:

At 08:24 PM 7/31/98 -0600, you wrote:
>
>
>---------- Forwarded message ----------
>Date: Fri, 31 Jul 98 16:35:08 PDT
>From: Dave Lochhaas <lochhaas-at-computerland-dot-net>
>To: Tesla List <tesla-at-pupman-dot-com>
>Subject: Carrying a Full Load
>
>Hi to the List from Mid-Missouri,
>
>I'm brand new and carrying a full load of questions.  To be fair, though, I
thought I would provide a few answers to frequently asked questions first.
The answers are: " Yes," "Yes," "Maybe," "Let me get back to you on that
one," and my favorite "You just don't get it do you."
>
>These are my questions:
>
>1.  I have a beefy old bug zapper that's spent the last fifteen years in
the garage in storage so it didn't suffer much when I took it apart.  It has
a transformer that will draw about a quarter inch arc across a gap.  Can I
build a small Tesla coil with this?  I've search all the websites but can't
find any reference this.


I have one here.  It measured 4300 VAC at 7.0 mA (30 VA) Probably enough to
make a small little coil.  Mine is an open frame transformer that has very
obvious primary and secondaries.  You can see the shunt between to two cores
that limits the current.  The secondary is vacuum encased in clear plastic
potting with silicon wires comming out.  Very straight forward.


>2.  The secondary of the above transformer has a red stubby cylindrical
component that is marked with:  MDC     10000M     Z5R     18KV.       What
is this thing?

It is a transorb.  Mine says  MDC 1000M Z5R  18Kv.  This transorb will
conduct currents above 18kV.  It protects the transformer from high voltage
spikes much as a spark gap would.  Leave it in the circuit.  It adds some
capacitance but gives good overvoltage protection.  It goes across the
output leads.


>
>3.  I've read that spark gap arcs, like arc welding arcs, emit harmful UV.
Does a Jacobs ladder also do this?  What is the physics by which UV is
produced in arcs such as these?

When an arc is made the air moelecules transition to a higher electron state
and fall back.  UV and all kinds of radiation is emmited.  Typically the
time this happens is so low that the effect is not a great concern.  Good
sunglasses or certainly welding glasses easily filter this raditation if you
are concerned.  The rule is if you look at the arc briefly and then close
your eyes and can see the image still "burned into your retnas" then you
should seek filters.

>
>4.  I got to examine the fluorescent tube circuitry in this bug zapper and
realized I really don't know how this works.  What I've got is an iron core
inductor in one leg of the AC feed that then goes to one pin at one end of
the bulb.  The other pin at the same end goes to the starter (a neon bulb
and cap in parallel) and then goes to one pin at the other end of the bulb.
And the other pin at this end goes to the other leg of the AC.  What's with
this thing?
>

It is the ballest.  Just a big inductive current limiter.  The starter
provides a kick that creates a voltage spike to get the tube started.  Then
the ballast limits the current to the tube.  These bulbs can run off 120 VAC
unlike neons that need big step up transformers.  They just need current
limiting and a voltage kick to start them.  There are also filiments in
these to help them emit electrons and allow low voltage operation.

>Okay, some pretty basic questions, I think.  Please don't use any of my
"answers" from above, especially, "You just don't get it do you," as I
already know that.
>
>Thanks for any help.  And hey, its Friday night.  I've got to get that bug
zapper back together, cause I've got a cold six pack, and its this evening's
entertainment.


I originally pulled my zapper apart and made a new "killing" grid for a
special wasp application :-) 

>
>Dave "the June bugs are the best" Lochhaas
>
>

        Terry Fritz