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Re: Help needed with old coil circuit

Original poster: robert heidlebaugh <rheidlebaugh@xxxxxxxxxxxxxx>

ROSIN CONTAMINATION can cause sevear current path problems. Dry alcohol
works well, but soap and water with good drieng may be required. Old medical
items I have restored usualy worh well. Shelac not rosin is most likely the
insulation used at the time your device was madel.
   Robert H

> From: "Tesla list" <tesla@xxxxxxxxxx>
> Date: Sat, 08 Jan 2005 09:18:44 -0700
> To: tesla@xxxxxxxxxx
> Subject: Help needed with old coil circuit
> Resent-From: tesla@xxxxxxxxxx
> Resent-Date: Sat, 8 Jan 2005 09:26:43 -0700 (MST)
> Original poster: peterB <zardoz@xxxxxxxxxx>
> Hello,
> I am in the process of restoring an old twin coil portable x ray
> apparatus made by Wappler.
> It has a strange circuit which doesn't make sense to me (keep in mind I
> have limited knowledge of circuits to begin with), but I have seen a
> number of old circuits (and new) that are close to this, but this one is
> odd.
> First, I have been in contact with one person who recognized the circuit
> but thought perhaps it was wired wrong at the factory (unless it was
> tampered with later, though it looks original) (supposed to have worked
> as wired though, I was told)
> The schematic and wiring diagram I drew from the machine is at:
> http://www.albany.net/~zardoz/wapplerschematic.html
> NOTE: the schematic and diagram of how it is currently wired appears
> just below the first two diagrams. The top two diagrams are based on
> what this person thought I should change in the circuit.
> The actual device (I am documenting its restoration) can be seen at:
> http://www.albany.net/~zardoz/wapplerapparatus.html
> (4 pages, although, the general idea of the actual machine can be seen
> in the black and white photo on the above page.)
> My questions: (refer to the two drawings below the revised drawings)
> The primary of the transformer is connected to the secondary. This I was
> told was a relatively common practice.
> I quote Frank:
> -----------------------------
> "2) The secondary connected to the primary is also a common wiring
> trick,
> this way the components do not need so much insulation. Also, the
> transformer is a high current, low voltage type. Probably a max of 2KV
> out,
> it is easy to tell this by the standard house wire on the secondary.
> Not to fear tho, the current is what makes the coils sing!"
> ---------------------------
> He suggested I switch the wires going to the primary, (see photo towards
> the bottom of the schematic page) These are the two wires that terminate
> at 'a' (spark gap) and 'b' (ac in). This change would result in the
> schematic at the top of the schematic page (and the new wiring diagram
> just below it.)
> Some other info Frank passed along:
> ---------------------------
> "3) As you probably guessed, with the secondary circuits connected to
> one
> side of the 110, the shock hazard is very great if you are grounded,
> even
> with the set off!
> 4) The cautery circuit is a true RF type, with the jumper removed, the
> circuit is a cap in series with the HV and you get a nice fat arc.
> 6) The Tesla circuit is with the cap(s) in series with the transformer
> and
> the spark gap is in parallel across the transformer output so it is very
> important NOT to ever close the gap completely as it will short out the
> transformer and pop the fuse.
> Now, the way you drew the circuit, the secondary is in series with the
> primary and this will not work. I think you will find the RH side of the
> gap connects to the common pri/sec side of the transformer and the
> rotary
> switch does not go to the gap. The set cannot work as drawn without
> frying
> the transformer."
> --------------------------
> The resulting arrangement shown by the schematic at the top looks like
> it would lead to HF leaking into the AC lines, as there is no choke.
> My question, if the re-arrangement of wires as Frank suggests is
> correct, will there be a danger of HF leaking into the AC lines?
> NOTE Diagrams: when the multi position switch is set to 1, 2, 3, or 4, I
> could see the voltage regulation coil acting as a choke, but at position
> 5, which by-passes this coil, there is no choke. Could the strange
> wiring as shown in the original schematic and diagram be wired that way
> so the transformer would act as a choke? Is it even possible to operate
> this apparatus without making the change Frank suggests, or should I
> switch the wires and add a choke (if a choke is necessary)?
> Thanks,
> -Pete