Volt / Ammeter

Yeah, I'll give you that I missed the "powered from the measured voltage"
part. It becomes a bit less trivial. Practically impossible.

As for sticking pins through the wire a foot apart, you are going to get
more contact resistance (and corrosion as time goes on) than the shunt
itself. If you are using the primary wire as the shunt, I'd break the wire,
use a terminal strip with a shorter piece of thinner wire a few inches long,
then back to the larger wire.

Jim


"GeorgeB" wrote in message
...
On Thu, 16 Feb 2006 21:35:15 -0800, "RST Engineering"
wrote:

Yes, rather trivially.

Stick 2 pins through the
insulation about a foot apart and hook them to the meter.

RST Engineering wrote:
Yeah, I'll give you that I missed the "powered from the measured voltage"
part. It becomes a bit less trivial. Practically impossible.

As for sticking pins through the wire a foot apart, you are going to get
more contact resistance (and corrosion as time goes on) than the shunt
itself. If you are using the primary wire as the shunt, I'd break the wire,
use a terminal strip with a shorter piece of thinner wire a few inches long,
then back to the larger wire.

Jim


"GeorgeB" wrote in message
...
On Thu, 16 Feb 2006 21:35:15 -0800, "RST Engineering"
wrote:

Yes, rather trivially.

Stick 2 pins through the
insulation about a foot apart and hook them to the meter.


Would AC amps and DC amps read the same given a single meter switched
between the two?

Dan, U.S. Air Force, retired

Would AC amps and DC amps read the same given a single meter switched
between the two?

Dan, U.S. Air Force, retired

G'day Dan,
they will normally read pretty close, but the meter (and you get what you
pay for...) will read an average of the applied AC or voltage.

This difference in reading will apply more to non-sinusoidal waveforms.

Some of the fancy meters will read "True RMS", but for most typical
applications a cheap meter will be close enough. To check the alternator
output in an aircraft....... Well, you could always log the data and apply a
calibration correction if you needed to be super-accurate.......

Hope this helps,
Peter

On Fri, 17 Feb 2006 10:07:50 -0800, "RST Engineering"
wrote:

Yeah, I'll give you that I missed the "powered from the measured voltage"
part. It becomes a bit less trivial. Practically impossible.

As for sticking pins through the wire a foot apart, you are going to get
more contact resistance (and corrosion as time goes on) than the shunt
itself. If you are using the primary wire as the shunt, I'd break the wire,
use a terminal strip with a shorter piece of thinner wire a few inches long,
then back to the larger wire.

I'm wondering if the OP may have mis worded, or mis understood.

As you say the measurement is trivial, however I'm wondering if he
didn't think of powering the meter from the same source as was
*providing* the current rather than the current being measured. That
would make sense. Then it'd be easy and as you said, practically
impossible if powered from the *measured* current.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Jim


"GeorgeB" wrote in message
.. .
On Thu, 16 Feb 2006 21:35:15 -0800, "RST Engineering"
wrote:

Yes, rather trivially.

Stick 2 pins through the
insulation about a foot apart and hook them to the meter.

"Roger" wrote in message
...
On Fri, 17 Feb 2006 10:07:50 -0800, "RST Engineering"
wrote:

Yeah, I'll give you that I missed the "powered from the measured voltage"
part. It becomes a bit less trivial. Practically impossible.

As for sticking pins through the wire a foot apart, you are going to get
more contact resistance (and corrosion as time goes on) than the shunt
itself. If you are using the primary wire as the shunt, I'd break the
wire,
use a terminal strip with a shorter piece of thinner wire a few inches
long,
then back to the larger wire.

I'm wondering if the OP may have mis worded, or mis understood.

As you say the measurement is trivial, however I'm wondering if he
didn't think of powering the meter from the same source as was
*providing* the current rather than the current being measured. That
would make sense. Then it'd be easy and as you said, practically
impossible if powered from the *measured* current.

What am I missing here? A good old fashioned analog ammeter is powered from
the "measured current".
Or, you can use a Simpson panel meter with your shunt. No power required. Of
course, they cost a fair bit of change nowadays.

http://www.simpsonelectric.com/pdf/w...-Vue%20ADC.pdf

You only need "power" if you want some kind of fancy pants digital readout.

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
Spell checking is left as an excercise for the reader.

Go back to the original post and read it.

Jim





"Capt. Geoffrey Thorpe" The Sea Hawk at wow way d0t com wrote in message
What am I missing here? A good old fashioned analog ammeter is powered
from the "measured current".

"RST Engineering" wrote in message
...
Go back to the original post and read it.

Jim

"Capt. Geoffrey Thorpe" The Sea Hawk at wow way d0t com wrote in message

What am I missing here? A good old fashioned analog ammeter is powered
from the "measured current".

oops, missed the word "digital". Never mind.

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
Spell checking is left as an excercise for the reader.