I have just bought a vintage (1943?) DC 25-kilovolt meter (for a
Steam-Punk style 10kv Jacob's Ladder project).

It is built into a box (photograph attached). On the underside of the
box someone has written:
Meter res = 50 ohm
LV res = 4950
Hi res = 99950

Inside the box are two resistors (one loose, one soldered one end to
an external terminal but not connected to the meter), values:
1 x 4950 ohms
1 x 95k ohm

The meter has three terminals, two main, one smaller in the centre.
The box has two connection terminals and a push-switch, which I
presume was intended to select the appropriate multiplier resistor.

I found an informative piece on rating by Curt Reed at
http://www.antiqueradios.com/forums/...ad4ccd433b5184
(posted: Jul Wed 21, 2010 10:16 pm)

If anyone knows what the central terminal is for, and can offer any
advice on how the meter could be wired for 25kv operation, that would
be better than my guesswork.

Thank you

glutinous wrote:
I have just bought a vintage (1943?) DC 25-kilovolt meter (for a
Steam-Punk style 10kv Jacob's Ladder project).

It is built into a box (photograph attached). On the underside of the
box someone has written:
Meter res = 50 ohm
LV res = 4950
Hi res = 99950

Inside the box are two resistors (one loose, one soldered one end to
an external terminal but not connected to the meter), values:
1 x 4950 ohms
1 x 95k ohm

The meter has three terminals, two main, one smaller in the centre.
The box has two connection terminals and a push-switch, which I
presume was intended to select the appropriate multiplier resistor.

I found an informative piece on rating by Curt Reed at
http://www.antiqueradios.com/forums/...ad4ccd433b5184
(posted: Jul Wed 21, 2010 10:16 pm)

If anyone knows what the central terminal is for, and can offer any
advice on how the meter could be wired for 25kv operation, that would
be better than my guesswork.

Thank you


That meter says "Calibrated at 50 ~", which says to me that it's an AC
microammeter with a display in volts.

Use with care.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net

Post it to www.instructables.com when you are done (and if you don't fry
yourself first). There are lots of 'Steam-Punk' projects there.
The Jacobs ladder is typically made with an ignition transformer from an oil
burning heating system. The secondary on these transformers is center tapped
with the tap going to case/earth. The output current is limited by the
internal core gap (iirc).
Might be a lot safer since the meter will not measure KV directly, that you
use a suitable scaling resistor and simply measure the mains (primary) side
of the transformer. For added effect, put a filament lamp of 100W or so in
series with the primary. Brightness is proportional to the current drawn and
gives a further current limit control. This may not give enough power for
the arc to travel up the column though.

Be safe!

"glutinous" wrote in message
...
I have just bought a vintage (1943?) DC 25-kilovolt meter (for a
Steam-Punk style 10kv Jacob's Ladder project).

On Fri, 3 Sep 2010 10:34:19 -0400, "Oppie"
wrote:

Post it to www.instructables.com when you are done (and if you don't fry
yourself first). There are lots of 'Steam-Punk' projects there.
The Jacobs ladder is typically made with an ignition transformer from an oil
burning heating system. The secondary on these transformers is center tapped
with the tap going to case/earth. The output current is limited by the
internal core gap (iirc).
Might be a lot safer since the meter will not measure KV directly, that you
use a suitable scaling resistor and simply measure the mains (primary) side
of the transformer. For added effect, put a filament lamp of 100W or so in
series with the primary. Brightness is proportional to the current drawn and
gives a further current limit control. This may not give enough power for
the arc to travel up the column though.

Be safe!

"glutinous" wrote in message
.. .
I have just bought a vintage (1943?) DC 25-kilovolt meter (for a
Steam-Punk style 10kv Jacob's Ladder project).



Thank you for the observations, Oppie.

As I just replied to PeterD, the Jacob's Ladder I referred to is built
and functions well, using (and I always get a childish pleasure out of
saying this) a 10kv FART transformer from a neon rig. It makets a nice
spark between two 30-inch copper rods, approx 2.5 inches at the wide
end.

In fact I already have a (low wattage) vintage industrial filament
lamp fitted to the front of the box it's built into, but it's wired in
parallel to the primary, and lights up when the low-voltage switching
side operates a relay to supply current to the FART (he he he snurk).
Anyway, I'm guessing it'd limit the juice so less spark.

It's an idea to try the meter on the mains side: it doesn't _really_
have to show a genuine 10kv, it's more for the look of the thing (tho'
it would be cool if it did - obviously without the frying bit).

BTW, the low-voltage relay side is operated by a small, old-style,
bakelite base circuit-breaker type switch (as in "throw the...").

Cheers!

On Thu, 02 Sep 2010 19:54:47 -0400, Phil Hobbs
wrote:

glutinous wrote:
I have just bought a vintage (1943?) DC 25-kilovolt meter (for a
Steam-Punk style 10kv Jacob's Ladder project).

It is built into a box (photograph attached). On the underside of the
box someone has written:
Meter res = 50 ohm
LV res = 4950
Hi res = 99950

Inside the box are two resistors (one loose, one soldered one end to
an external terminal but not connected to the meter), values:
1 x 4950 ohms
1 x 95k ohm

The meter has three terminals, two main, one smaller in the centre.
The box has two connection terminals and a push-switch, which I
presume was intended to select the appropriate multiplier resistor.

I found an informative piece on rating by Curt Reed at
http://www.antiqueradios.com/forums/...ad4ccd433b5184
(posted: Jul Wed 21, 2010 10:16 pm)

If anyone knows what the central terminal is for, and can offer any
advice on how the meter could be wired for 25kv operation, that would
be better than my guesswork.

Thank you


That meter says "Calibrated at 50 ~", which says to me that it's an AC
microammeter with a display in volts.

Okeydokey Phil, thank you.

Use with care.

That's why I posted here before doing ANYTHING!


Cheers

Phil Hobbs

Cheers back at you. Thanks!

"glutinous" wrote in message
...
As I just replied to PeterD, the Jacob's Ladder I referred to is built
and functions well, using (and I always get a childish pleasure out of
saying this) a 10kv FART transformer from a neon rig. It makets a nice
spark between two 30-inch copper rods, approx 2.5 inches at the wide
end.

In fact I already have a (low wattage) vintage industrial filament
lamp fitted to the front of the box it's built into, but it's wired in
parallel to the primary, and lights up when the low-voltage switching
side operates a relay to supply current to the FART (he he he snurk).
Anyway, I'm guessing it'd limit the juice so less spark.

It's an idea to try the meter on the mains side: it doesn't _really_
have to show a genuine 10kv, it's more for the look of the thing (tho'
it would be cool if it did - obviously without the frying bit).

BTW, the low-voltage relay side is operated by a small, old-style,
bakelite base circuit-breaker type switch (as in "throw the...").

Cheers!

Figured that 'FART transformer' had to be a UK reference. Never heard of it
in the USA.
http://www.signtechnology.co.nz/f.a.r.t.php Doesn't give much information
about products.
http://www.bigclive.com/jacobs.htm is more informative.
In spite of the name, France Transformer is one of the more common sign
transformers used in the USA. Sorry, no 'snurk' factor on this manufacturer.
http://www.franceformer.com/index.html

On Sun, 5 Sep 2010 22:43:52 -0400, "Oppie" wrote:

"glutinous" wrote in message
.. .
As I just replied to PeterD, the Jacob's Ladder I referred to is built
and functions well, using (and I always get a childish pleasure out of
saying this) a 10kv FART transformer from a neon rig. It makets a nice
spark between two 30-inch copper rods, approx 2.5 inches at the wide
end.

In fact I already have a (low wattage) vintage industrial filament
lamp fitted to the front of the box it's built into, but it's wired in
parallel to the primary, and lights up when the low-voltage switching
side operates a relay to supply current to the FART (he he he snurk).
Anyway, I'm guessing it'd limit the juice so less spark.

It's an idea to try the meter on the mains side: it doesn't _really_
have to show a genuine 10kv, it's more for the look of the thing (tho'
it would be cool if it did - obviously without the frying bit).

BTW, the low-voltage relay side is operated by a small, old-style,
bakelite base circuit-breaker type switch (as in "throw the...").

Cheers!

Figured that 'FART transformer' had to be a UK reference. Never heard of it
in the USA.
http://www.signtechnology.co.nz/f.a.r.t.php Doesn't give much information
about products.
http://www.bigclive.com/jacobs.htm is more informative.
In spite of the name, France Transformer is one of the more common sign
transformers used in the USA. Sorry, no 'snurk' factor on this manufacturer.
http://www.franceformer.com/index.html



Thanks for the reply.

FART GmbH is a German company, as far as I know (tho' that's Fabbrica
Apparecchiature Radioelettriche Treviso). It's not all Benny Hill over
here you know... :-)

Website (under 'renovation'): http://www.fart-neon.de/

Some info on the transformer:
http://www.signbuyer.co.uk/neon-fart...mer-2286-p.asp

glutinous wrote:

On Sun, 5 Sep 2010 22:43:52 -0400, "Oppie" wrote:

"glutinous" wrote in message
.. .
As I just replied to PeterD, the Jacob's Ladder I referred to is built
and functions well, using (and I always get a childish pleasure out of
saying this) a 10kv FART transformer from a neon rig. It makets a nice
spark between two 30-inch copper rods, approx 2.5 inches at the wide
end.

In fact I already have a (low wattage) vintage industrial filament
lamp fitted to the front of the box it's built into, but it's wired in
parallel to the primary, and lights up when the low-voltage switching
side operates a relay to supply current to the FART (he he he snurk).
Anyway, I'm guessing it'd limit the juice so less spark.

It's an idea to try the meter on the mains side: it doesn't _really_
have to show a genuine 10kv, it's more for the look of the thing (tho'
it would be cool if it did - obviously without the frying bit).

BTW, the low-voltage relay side is operated by a small, old-style,
bakelite base circuit-breaker type switch (as in "throw the...").

Cheers!

Figured that 'FART transformer' had to be a UK reference. Never heard of it
in the USA.
http://www.signtechnology.co.nz/f.a.r.t.php Doesn't give much information
about products.
http://www.bigclive.com/jacobs.htm is more informative.
In spite of the name, France Transformer is one of the more common sign
transformers used in the USA. Sorry, no 'snurk' factor on this manufacturer.
http://www.franceformer.com/index.html



Thanks for the reply.

FART GmbH is a German company, as far as I know (tho' that's Fabbrica
Apparecchiature Radioelettriche Treviso). It's not all Benny Hill over
here you know... :-)


Glow in the dark FARTs? Dimbulb will be so jealous!


--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

On Sun, 12 Sep 2010 01:24:22 +0100, glutinous
wrote:

[snip]

FART GmbH is a German company, as far as I know (tho' that's Fabbrica
Apparecchiature Radioelettriche Treviso). It's not all Benny Hill over
here you know... :-)

[snip]

I don't know... I certainly saw a lot of ausfahrt- and einfahrt-ing
when I was in Germany... as well as some other fahrt-ing that I don't
know what it meant ;-)

...Jim Thompson
--
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| Voice480)460-2350 Fax: Available upon request | Brass Rat |
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