Arcane question, and sort of long, but here goes....

Last night, young son was in the process of adding foglights to his car
and asked me for some wire to extend the harness. I wasn't sure what the
current draw would be so I grabbed one of the foglight assemblies and
connected it to the Eico 1050 battery charger/DC power supply which has
been part of my garage tool clutter for nearly 50 years:

http://home.comcast.net/~jwisnia18/temp/eico1050.jpg

When I cranked the voltage up to 13, the bulb lit brightly and the
ammeter on the Eico read around 9 amps. That seemed sort of high to me
so I asked the kid, "How big a fuse is in the harness which came with
those lights?" he looked at it and told me it was a 15 amp fuse. 15 amps
for TWO 9 amp bulbs? Obviously something was't right, so I got my
Simpson 260 and saw that the current drawn by that bulb was really a bit
less than 5 amps.

Since SWMBO was out getting some "retail therapy" I had some free time,
and taking the Eico into my workshop, I opened it up, disconnected the
leads to the ammeter and fed it with my bench supply. That verified
again that it was reading almost twice the DC current passing through it.

By a couple of "cut and trys" I found that about 4 inches of 18 gage
solid copper wire shunting the meter made it read correctly enough for
"gummint work", so I soldered that wire in and closed the Eico back up.

I believe the ammmeter is what I used to know as a "moving iron" type,
and IIRC the restoring force was supplied by some kind of permanant
magnet field, not by a mechanical spring. Am I right about that?

I doubt that Eico installed a defective meter when they built the unit
around 1965 (The date marked on the meter.) and I'm guessing that the
meter's restoring magnet weakened over 50 years, increasing its
sensitivity to nearly double.

Anyone have any similar experience with those kind of meters, I'd enjoy
learning more, just for the ****s and grins of it.

Thanks guys,

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
"Rudeness is the weak man's imitation of strength."

Jeff Wisnia wrote:

Arcane question, and sort of long, but here goes....

Last night, young son was in the process of adding foglights to his car
and asked me for some wire to extend the harness. I wasn't sure what the
current draw would be so I grabbed one of the foglight assemblies and
connected it to the Eico 1050 battery charger/DC power supply which has
been part of my garage tool clutter for nearly 50 years:

http://home.comcast.net/~jwisnia18/temp/eico1050.jpg

When I cranked the voltage up to 13, the bulb lit brightly and the
ammeter on the Eico read around 9 amps. That seemed sort of high to me
so I asked the kid, "How big a fuse is in the harness which came with
those lights?" he looked at it and told me it was a 15 amp fuse. 15 amps
for TWO 9 amp bulbs? Obviously something was't right, so I got my
Simpson 260 and saw that the current drawn by that bulb was really a bit
less than 5 amps.

Since SWMBO was out getting some "retail therapy" I had some free time,
and taking the Eico into my workshop, I opened it up, disconnected the
leads to the ammeter and fed it with my bench supply. That verified
again that it was reading almost twice the DC current passing through it.

By a couple of "cut and trys" I found that about 4 inches of 18 gage
solid copper wire shunting the meter made it read correctly enough for
"gummint work", so I soldered that wire in and closed the Eico back up.

I believe the ammmeter is what I used to know as a "moving iron" type,
and IIRC the restoring force was supplied by some kind of permanant
magnet field, not by a mechanical spring. Am I right about that?

I doubt that Eico installed a defective meter when they built the unit
around 1965 (The date marked on the meter.) and I'm guessing that the
meter's restoring magnet weakened over 50 years, increasing its
sensitivity to nearly double.

Anyone have any similar experience with those kind of meters, I'd enjoy
learning more, just for the ****s and grins of it.

Thanks guys,

Jeff


Isn't there normally a shunt across the meter movement? If so, is it
accurate? If it had changed in value that could account for the
increased reading.

Ken wrote:
Jeff Wisnia wrote:


Arcane question, and sort of long, but here goes....

Last night, young son was in the process of adding foglights to his
car and asked me for some wire to extend the harness. I wasn't sure
what the current draw would be so I grabbed one of the foglight
assemblies and connected it to the Eico 1050 battery charger/DC power
supply which has been part of my garage tool clutter for nearly 50 years:

http://home.comcast.net/~jwisnia18/temp/eico1050.jpg

When I cranked the voltage up to 13, the bulb lit brightly and the
ammeter on the Eico read around 9 amps. That seemed sort of high to me
so I asked the kid, "How big a fuse is in the harness which came with
those lights?" he looked at it and told me it was a 15 amp fuse. 15
amps for TWO 9 amp bulbs? Obviously something was't right, so I got my
Simpson 260 and saw that the current drawn by that bulb was really a
bit less than 5 amps.

Since SWMBO was out getting some "retail therapy" I had some free
time, and taking the Eico into my workshop, I opened it up,
disconnected the leads to the ammeter and fed it with my bench supply.
That verified again that it was reading almost twice the DC current
passing through it.

By a couple of "cut and trys" I found that about 4 inches of 18 gage
solid copper wire shunting the meter made it read correctly enough for
"gummint work", so I soldered that wire in and closed the Eico back up.

I believe the ammmeter is what I used to know as a "moving iron" type,
and IIRC the restoring force was supplied by some kind of permanant
magnet field, not by a mechanical spring. Am I right about that?

I doubt that Eico installed a defective meter when they built the unit
around 1965 (The date marked on the meter.) and I'm guessing that the
meter's restoring magnet weakened over 50 years, increasing its
sensitivity to nearly double.

Anyone have any similar experience with those kind of meters, I'd
enjoy learning more, just for the ****s and grins of it.

Thanks guys,

Jeff


Isn't there normally a shunt across the meter movement? If so, is
it accurate? If it had changed in value that could account for the
increased reading.


There was none across the outside, and the meter was crimped shut, so I
didn't bother looking inside.

But IIRC that kind of meter just used a few turns of heavy wire
connected across it's terminals to create a magnetic field which altered
the total dc magnetic field inside and made a piece of iron on the
pointer shaft change its position.

Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
"Rudeness is the weak man's imitation of strength."

Jeff Wisnia wrote:
Ken wrote:
Jeff Wisnia wrote:

Arcane question, and sort of long, but here goes....

Last night, young son was in the process of adding foglights to his
car and asked me for some wire to extend the harness. I wasn't sure
what the current draw would be so I grabbed one of the foglight
assemblies and connected it to the Eico 1050 battery charger/DC power
supply which has been part of my garage tool clutter for nearly 50 years:

http://home.comcast.net/~jwisnia18/temp/eico1050.jpg

When I cranked the voltage up to 13, the bulb lit brightly and the
ammeter on the Eico read around 9 amps. That seemed sort of high to me
so I asked the kid, "How big a fuse is in the harness which came with
those lights?" he looked at it and told me it was a 15 amp fuse. 15
amps for TWO 9 amp bulbs? Obviously something was't right, so I got my
Simpson 260 and saw that the current drawn by that bulb was really a
bit less than 5 amps.

Since SWMBO was out getting some "retail therapy" I had some free
time, and taking the Eico into my workshop, I opened it up,
disconnected the leads to the ammeter and fed it with my bench supply.
That verified again that it was reading almost twice the DC current
passing through it.

By a couple of "cut and trys" I found that about 4 inches of 18 gage
solid copper wire shunting the meter made it read correctly enough for
"gummint work", so I soldered that wire in and closed the Eico back up.

I believe the ammmeter is what I used to know as a "moving iron" type,
and IIRC the restoring force was supplied by some kind of permanant
magnet field, not by a mechanical spring. Am I right about that?

I doubt that Eico installed a defective meter when they built the unit
around 1965 (The date marked on the meter.) and I'm guessing that the
meter's restoring magnet weakened over 50 years, increasing its
sensitivity to nearly double.

Anyone have any similar experience with those kind of meters, I'd
enjoy learning more, just for the ****s and grins of it.

Thanks guys,

Jeff

Isn't there normally a shunt across the meter movement? If so, is
it accurate? If it had changed in value that could account for the
increased reading.

There was none across the outside, and the meter was crimped shut, so I
didn't bother looking inside.

But IIRC that kind of meter just used a few turns of heavy wire
connected across it's terminals to create a magnetic field which altered
the total dc magnetic field inside and made a piece of iron on the
pointer shaft change its position.

Jeff

Those moving iron ones didnt usually use shunts, as you say. They were
cheap, nonlinear, undamped and inaccurate, and I expect the meter's
always been that way. It was probably a bit of marketing spin.


NT

wrote:
Jeff Wisnia wrote:


Since SWMBO was out getting some "retail therapy" I had some free
time, and taking the Eico into my workshop, I opened it up,
disconnected the leads to the ammeter and fed it with my bench supply.
That verified again that it was reading almost twice the DC current
passing through it.

if you want it to read right, remove a turn or 2 on the coil. Not sure
if I'd bother though.

NT

Jeff Wisnia wrote:

Ken wrote:

Jeff Wisnia wrote:


Arcane question, and sort of long, but here goes....

Last night, young son was in the process of adding foglights to his
car and asked me for some wire to extend the harness. I wasn't sure
what the current draw would be so I grabbed one of the foglight
assemblies and connected it to the Eico 1050 battery charger/DC power
supply which has been part of my garage tool clutter for nearly 50
years:

http://home.comcast.net/~jwisnia18/temp/eico1050.jpg

When I cranked the voltage up to 13, the bulb lit brightly and the
ammeter on the Eico read around 9 amps. That seemed sort of high to
me so I asked the kid, "How big a fuse is in the harness which came
with those lights?" he looked at it and told me it was a 15 amp fuse.
15 amps for TWO 9 amp bulbs? Obviously something was't right, so I
got my Simpson 260 and saw that the current drawn by that bulb was
really a bit less than 5 amps.

Since SWMBO was out getting some "retail therapy" I had some free
time, and taking the Eico into my workshop, I opened it up,
disconnected the leads to the ammeter and fed it with my bench
supply. That verified again that it was reading almost twice the DC
current passing through it.

By a couple of "cut and trys" I found that about 4 inches of 18 gage
solid copper wire shunting the meter made it read correctly enough
for "gummint work", so I soldered that wire in and closed the Eico
back up.

I believe the ammmeter is what I used to know as a "moving iron"
type, and IIRC the restoring force was supplied by some kind of
permanant magnet field, not by a mechanical spring. Am I right about
that?

I doubt that Eico installed a defective meter when they built the
unit around 1965 (The date marked on the meter.) and I'm guessing
that the meter's restoring magnet weakened over 50 years, increasing
its sensitivity to nearly double.

Anyone have any similar experience with those kind of meters, I'd
enjoy learning more, just for the ****s and grins of it.

Thanks guys,

Jeff


Isn't there normally a shunt across the meter movement? If so, is
it accurate? If it had changed in value that could account for the
increased reading.



There was none across the outside, and the meter was crimped shut, so I
didn't bother looking inside.

But IIRC that kind of meter just used a few turns of heavy wire
connected across it's terminals to create a magnetic field which altered
the total dc magnetic field inside and made a piece of iron on the
pointer shaft change its position.

Jeff
Yep, that is the standard construction; i think a spring was used for
setting / resetting zero position.

Ken wrote:

Jeff Wisnia wrote:


Arcane question, and sort of long, but here goes....

Last night, young son was in the process of adding foglights to his
car and asked me for some wire to extend the harness. I wasn't sure
what the current draw would be so I grabbed one of the foglight
assemblies and connected it to the Eico 1050 battery charger/DC power
supply which has been part of my garage tool clutter for nearly 50 years:

http://home.comcast.net/~jwisnia18/temp/eico1050.jpg

When I cranked the voltage up to 13, the bulb lit brightly and the
ammeter on the Eico read around 9 amps. That seemed sort of high to me
so I asked the kid, "How big a fuse is in the harness which came with
those lights?" he looked at it and told me it was a 15 amp fuse. 15
amps for TWO 9 amp bulbs? Obviously something was't right, so I got my
Simpson 260 and saw that the current drawn by that bulb was really a
bit less than 5 amps.

Since SWMBO was out getting some "retail therapy" I had some free
time, and taking the Eico into my workshop, I opened it up,
disconnected the leads to the ammeter and fed it with my bench supply.
That verified again that it was reading almost twice the DC current
passing through it.

By a couple of "cut and trys" I found that about 4 inches of 18 gage
solid copper wire shunting the meter made it read correctly enough for
"gummint work", so I soldered that wire in and closed the Eico back up.

I believe the ammmeter is what I used to know as a "moving iron" type,
and IIRC the restoring force was supplied by some kind of permanant
magnet field, not by a mechanical spring. Am I right about that?

I doubt that Eico installed a defective meter when they built the unit
around 1965 (The date marked on the meter.) and I'm guessing that the
meter's restoring magnet weakened over 50 years, increasing its
sensitivity to nearly double.

Anyone have any similar experience with those kind of meters, I'd
enjoy learning more, just for the ****s and grins of it.

Thanks guys,

Jeff


Isn't there normally a shunt across the meter movement? If so, is
it accurate? If it had changed in value that could account for the
increased reading.
Cheap high DC current meters were almost always iron vane and never
had a shunt.

"Jeff Wisnia" wrote in message
et...

I believe the ammmeter is what I used to know as a "moving iron" type, and
IIRC the restoring force was supplied by some kind of permanant magnet
field, not by a mechanical spring. Am I right about that?

Nope. Still a spring.

http://www.tpub.com/content/doe/h101...h1011v4_76.htm

Moving iron vane - The moving iron vane meter operates on the
principle of magnetic repulsion between like poles. The measured current
flows through a field coil which induces a like magnetic field into
a fixed and moving vane causing the moving vane to deflect a
pointer in proportion to the current or voltage applied to the coil.

Homer J Simpson wrote:

"Jeff Wisnia" wrote in message
et...


I believe the ammmeter is what I used to know as a "moving iron" type, and
IIRC the restoring force was supplied by some kind of permanant magnet
field, not by a mechanical spring. Am I right about that?


Nope. Still a spring.

http://www.tpub.com/content/doe/h101...h1011v4_76.htm

Moving iron vane - The moving iron vane meter operates on the
principle of magnetic repulsion between like poles. The measured current
flows through a field coil which induces a like magnetic field into
a fixed and moving vane causing the moving vane to deflect a
pointer in proportion to the current or voltage applied to the coil.



I hear what you say about a spring, and it makes sense that there may be
one there. But it's interesting that the reference link you gave
mentioned "springs" when describing the first two meter types, but not
the moving iron one. Wonder why? Probably just an oversight.

Jeff (Who is NOT going to tear that old meter on the Eico 1050 apart to
find out.)

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
"Rudeness is the weak man's imitation of strength."

"Jeff Wisnia" wrote in message
et...

I hear what you say about a spring, and it makes sense that there may be
one there. But it's interesting that the reference link you gave mentioned
"springs" when describing the first two meter types, but not the moving
iron one. Wonder why? Probably just an oversight.

Perhaps they felt it was redundant. It's like holding two magnets N to N and
S to S - you are the spring holding them together.

Jeff Wisnia wrote in
et:

Homer J Simpson wrote:

"Jeff Wisnia" wrote in message
et...


I believe the ammmeter is what I used to know as a "moving iron"
type, and IIRC the restoring force was supplied by some kind of
permanant magnet field, not by a mechanical spring. Am I right about
that?


Nope. Still a spring.

http://www.tpub.com/content/doe/h101...h1011v4_76.htm

Moving iron vane - The moving iron vane meter operates on
the principle of magnetic repulsion between like poles. The
measured current flows through a field coil which induces a like
magnetic field into a fixed and moving vane causing the
moving vane to deflect a pointer in proportion to the
current or voltage applied to the coil.



I hear what you say about a spring, and it makes sense that there may
be one there. But it's interesting that the reference link you gave
mentioned "springs" when describing the first two meter types, but not
the moving iron one. Wonder why? Probably just an oversight.

Jeff (Who is NOT going to tear that old meter on the Eico 1050 apart
to find out.)


You can test for a spring without dissection. First, does the meter jump to
a position and oscillate a bit before settling? If so, put your ear (or a
stethoscope) to the meter panel and tap it sharply. If there's a spring in
there it should ring like a bell. If you see that resonace in the meter
movement, yet hear no spring, then you and Homer are probably right, the
spring would be entirely magnetic.

The pointer itself might ring with the test I described, but dull sound,
not the sustained ring you'd likely hear from a spring designed to maintain
a pointer position.

Jeff Wisnia wrote:
Homer J Simpson wrote:

"Jeff Wisnia" wrote in message
et...


I believe the ammmeter is what I used to know as a "moving iron"
type, and IIRC the restoring force was supplied by some kind of
permanant magnet field, not by a mechanical spring. Am I right about
that?


Nope. Still a spring.

http://www.tpub.com/content/doe/h101...h1011v4_76.htm

Moving iron vane - The moving iron vane meter operates on
the principle of magnetic repulsion between like poles. The
measured current flows through a field coil which induces a like
magnetic field into a fixed and moving vane causing the moving
vane to deflect a pointer in proportion to the current or
voltage applied to the coil.



I hear what you say about a spring, and it makes sense that there may be
one there. But it's interesting that the reference link you gave
mentioned "springs" when describing the first two meter types, but not
the moving iron one. Wonder why? Probably just an oversight.

Jeff (Who is NOT going to tear that old meter on the Eico 1050 apart to
find out.)

Hit the 'Back' link at the top of the page above and you'll see the
spring.


--
Graham W http://www.gcw.org.uk/ PGM-FI page updated, Graphics Tutorial
WIMBORNE http://www.wessex-astro.org.uk/ Wessex Astro Society's Website
Dorset UK Info, Meeting Dates, Sites & Maps
Change 'news' to 'sewn' in my Reply address to avoid my spam filter.

Graham W wrote:


Jeff Wisnia wrote:

Homer J Simpson wrote:


"Jeff Wisnia" wrote in message
news:zLydnZVzrJEpLYfYnZ2dnUVZ_tWdnZ2d@conversen t.net...



I believe the ammmeter is what I used to know as a "moving iron"
type, and IIRC the restoring force was supplied by some kind of
permanant magnet field, not by a mechanical spring. Am I right about
that?


Nope. Still a spring.

http://www.tpub.com/content/doe/h101...h1011v4_76.htm

Moving iron vane - The moving iron vane meter operates on
the principle of magnetic repulsion between like poles. The
measured current flows through a field coil which induces a like
magnetic field into a fixed and moving vane causing the moving
vane to deflect a pointer in proportion to the current or
voltage applied to the coil.




I hear what you say about a spring, and it makes sense that there may be
one there. But it's interesting that the reference link you gave
mentioned "springs" when describing the first two meter types, but not
the moving iron one. Wonder why? Probably just an oversight.

Jeff (Who is NOT going to tear that old meter on the Eico 1050 apart to
find out.)


Hit the 'Back' link at the top of the page above and you'll see the
spring.

Got it, thanks!

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
"Rudeness is the weak man's imitation of strength."

"Jeff Wisnia" wrote in message
et...

Arcane question, and sort of long, but here goes....

Anyone have any similar experience with those kind of meters, I'd enjoy
learning more, just for the ****s and grins of it.

Thanks guys,

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
"Rudeness is the weak man's imitation of strength."

It's called Google and you don't play facile and excuse yourself with a poor
tag line.

DNA
"Try not to speak"

"Genome" wrote in
:


"Jeff Wisnia" wrote in message
et...

Arcane question, and sort of long, but here goes....

Anyone have any similar experience with those kind of meters, I'd
enjoy learning more, just for the ****s and grins of it.

Thanks guys,

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
"Rudeness is the weak man's imitation of strength."

It's called Google and you don't play facile and excuse yourself with
a poor tag line.

DNA
"Try not to speak"




Oops! Looks like the missing molecules spilled over again out of the blue
like they did on me some time back. On the subject of practising what we
preach, DNA might do well to speak less. Move along people, nothing to see
here. And don't get any on you!

Jeff Wisnia wrote:
Arcane question, and sort of long, but here goes....

Last night, young son was in the process of adding foglights to his car
and asked me for some wire to extend the harness. I wasn't sure what the
current draw would be so I grabbed one of the foglight assemblies and
connected it to the Eico 1050 battery charger/DC power supply which has
been part of my garage tool clutter for nearly 50 years:

http://home.comcast.net/~jwisnia18/temp/eico1050.jpg

When I cranked the voltage up to 13, the bulb lit brightly and the
ammeter on the Eico read around 9 amps. That seemed sort of high to me
so I asked the kid, "How big a fuse is in the harness which came with
those lights?" he looked at it and told me it was a 15 amp fuse. 15 amps
for TWO 9 amp bulbs? Obviously something was't right, so I got my
Simpson 260 and saw that the current drawn by that bulb was really a bit
less than 5 amps.

Since SWMBO was out getting some "retail therapy" I had some free time,
and taking the Eico into my workshop, I opened it up, disconnected the
leads to the ammeter and fed it with my bench supply. That verified
again that it was reading almost twice the DC current passing through it.

By a couple of "cut and trys" I found that about 4 inches of 18 gage
solid copper wire shunting the meter made it read correctly enough for
"gummint work", so I soldered that wire in and closed the Eico back up.

I believe the ammmeter is what I used to know as a "moving iron" type,
and IIRC the restoring force was supplied by some kind of permanant
magnet field, not by a mechanical spring. Am I right about that?

I doubt that Eico installed a defective meter when they built the unit
around 1965 (The date marked on the meter.) and I'm guessing that the
meter's restoring magnet weakened over 50 years, increasing its
sensitivity to nearly double.

Anyone have any similar experience with those kind of meters, I'd enjoy
learning more, just for the ****s and grins of it.

Could it be that the meter was calibrated to compensate for the fact
that when it's hooked to a battery, it only supplies current when the
charger exceeds the battery's voltage, while on a lamp it would draw
current from zero on up?
--
John

On 27 Sep 2006 17:16:37 -0700, "John O'Flaherty"
wrote:


Could it be that the meter was calibrated to compensate for the fact
that when it's hooked to a battery, it only supplies current when the
charger exceeds the battery's voltage, while on a lamp it would draw
current from zero on up?


No.

John

Hello John,


Could it be that the meter was calibrated to compensate for the fact
that when it's hooked to a battery, it only supplies current when the
charger exceeds the battery's voltage, while on a lamp it would draw
current from zero on up?

No.


Then maybe the meter was calibrated so it would adjust the indicated
current according to the consumer price index. Now wait, with a build
date of 1965 that doesn't computer either...

--
SCNR, Joerg

http://www.analogconsultants.com

On Wed, 27 Sep 2006 17:27:46 -0700, John Larkin
wrote:

On 27 Sep 2006 17:16:37 -0700, "John O'Flaherty"
wrote:


Could it be that the meter was calibrated to compensate for the fact
that when it's hooked to a battery, it only supplies current when the
charger exceeds the battery's voltage, while on a lamp it would draw
current from zero on up?


No.

John

Also comes to mind that if there is a magnetic pointer restraint this
is unusual, and perhaps the meter would (as usual) have bal;ance
weights to restore to zero, so perhaps it is calibrated for when the
meter face is vertical (panel mount style)? A moving iron movement
responds to RMS so waveform should not be a problem.

Peter Dettmann

Peter Dettmann wrote:

On Wed, 27 Sep 2006 17:27:46 -0700, John Larkin
wrote:


On 27 Sep 2006 17:16:37 -0700, "John O'Flaherty"
wrote:



Could it be that the meter was calibrated to compensate for the fact
that when it's hooked to a battery, it only supplies current when the
charger exceeds the battery's voltage, while on a lamp it would draw
current from zero on up?


No.

John


Also comes to mind that if there is a magnetic pointer restraint this
is unusual, and perhaps the meter would (as usual) have bal;ance
weights to restore to zero, so perhaps it is calibrated for when the
meter face is vertical (panel mount style)? A moving iron movement
responds to RMS so waveform should not be a problem.

Peter Dettmann

FWIW I just went down and tried an orientation test with the meter
reading 5 amps and the pointer stayed in the same position whichever way
I tipped the unit.

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
"Rudeness is the weak man's imitation of strength."

"Jeff Wisnia" wrote in message
...
Peter Dettmann wrote:

[snip]


Also comes to mind that if there is a magnetic pointer restraint this
is unusual, and perhaps the meter would (as usual) have bal;ance
weights to restore to zero, so perhaps it is calibrated for when the
meter face is vertical (panel mount style)? A moving iron movement
responds to RMS so waveform should not be a problem.

Peter Dettmann

FWIW I just went down and tried an orientation test with the meter
reading 5 amps and the pointer stayed in the same position whichever way
I tipped the unit.


When I worked as a meter tech for EIL many years ago we calibrated iron
vane meters of various types. Most of them had a moveable metal piece that
could be adjusted to affect the calibration. Most of these meters were made
to be opened easily for repair and adjustment and scale changing, but some
(GE I think) had an aluminum band that was swaged on with a special tool to
seal the meter. All iron vane meters I worked on were for AC use, but they
might work on DC. I never tried. However, I think they relied on magnetic
induction which is an AC phenomenon, similar to a motor.

The really cheap meters were Shurite, and they used (I think) a permanent
magnet moving vane in a fixed coil. These were often DC meters used in
automotive and battery charger applications. The permanent magnet might
weaken with age, but I think that would make the meter read lower, rather
than high. If there were no magnetism, it would read zero. All meters I
worked on had springs (taut band types use the band as a spring). A weak
spring could cause a high reading.

The only meters I know to be true RMS are dynamometer types, which use a
moving coil as well as a fixed coil. When the coils are wired in series or
parallel, they read voltage or current. When the coils are separate, the
meter can be used as a wattmeter.

Of course, most such measurement is now done digitally, but it is
interesting and educational to understand the older technology. Also, many
of the lab grade meters were beautiful works of art, with varnished oak or
bakelite cases, and carefully drawn mirror scales to reduce parallax, and
to obtain accuracy to 1/4% or better.

Paul

I'm interested in this thread, having built a 1050 back in the late '50s.
It too has been part of the garage clutter for fifty years or so.

However, I am NOT willing to wade through two or three pages of quote,
quotequote, quotequotequote to get to one or two lines of answer.

PLEASE, PEOPLE, LEARN HOW TO SNIP.

Jim

RST Engineering (jw) wrote:
I'm interested in this thread, having built a 1050 back in the late '50s.
It too has been part of the garage clutter for fifty years or so.

Would you be willing to give the ammeter on your 1050 a quick check
against something you trust, either another ammeter or maybe a low
ohmage power resistor and a voltmeter and see if your unit's ammeter
reads high like mine did?


However, I am NOT willing to wade through two or three pages of quote,
quotequote, quotequotequote to get to one or two lines of answer.

PLEASE, PEOPLE, LEARN HOW TO SNIP.

Jim



I keep hearing opposing points of view about that, same as I do with
cross posting vs. duplicated separate posts.

I can see some merit to both sides of those two debates.

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
"Rudeness is the weak man's imitation of strength."

In article ,
Jeff Wisnia wrote:
....
current draw would be so I grabbed one of the foglight assemblies and
connected it to the Eico 1050 battery charger/DC power supply which has
been part of my garage tool clutter for nearly 50 years:

Er, are you feeding a peak reading meter the unfiltered output of
a full wave rectifier?

Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)

Mark Zenier wrote:
In article ,
Jeff Wisnia wrote:
...

current draw would be so I grabbed one of the foglight assemblies and
connected it to the Eico 1050 battery charger/DC power supply which has
been part of my garage tool clutter for nearly 50 years:


Er, are you feeding a peak reading meter the unfiltered output of
a full wave rectifier?



Just dropped back in, and in response to your question, the EICO does
have a pretty large filter cap in it, though I can't testify to how many
of its microfarads may have grown legs and run away over the years.

However, the check I performed against my bench supply, which is
definitely well filtered, confirmed the ammeter's calibration error.


I got a few giggles reading some of the interchanges on this thread I
started, between "Homer J Simpson" and others.

I'm thinking that some of the participants' alimentary canals may have
somehow gotten completely reversed. Medical miricals, to be sure.

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.

Jeff Wisnia wrote in news:x9udnZ-VU-
:

I'm thinking that some of the participants' alimentary canals may have
somehow gotten completely reversed.

That's been said to be even worse than it sounds. (House...)

On Thu, 09 Nov 2006 16:03:46 -0500, Jeff Wisnia wrote:

I'm thinking that some of the participants' alimentary canals may have
somehow gotten completely reversed. Medical miricals, to be sure.


Sounds like a case of optical rectusis - when the optic nerve gets
scrambled with the nerve to the bowels.

It gives you a ****ty outlook on life. ;-)

Cheers!
Rich