[Boatanchors] general OT question on panel meters
J. Forster
jfor at quikus.com
Tue Jul 9 13:20:04 EDT 2013
You run into terminal resistance issues.
If you want to make a shunt, try this:
O===o===========o===O
| |
---- M ----
The main current flows through O=========O
The o represent joints, where tge meter leads are soldered to the uncut
main conductor.
You can get the spacing right by soldering one and using a clip lead for
thge other. When you find the right point, solder it.
-John
=======================
> Ohm's law again.
>
> The resistance of the shunt should be 0.05V / 30A = 0.0016666666666667
> ohms (hard to measure)
>
> 50mV is the usual standard voltage drop across a shunt at it's rated
> current. So a 100 amp shunt won't do it.
>
> From the "COPPER WIRE TABLE" <http://www.w4zt.com/wire/> ,#10 is .9989
> ohms per 1000 feet. So cut a piece of #10 copper to 0.001666/.9989 *
> 1000 = 1.668 feet and use it as the shunt.
>
> Somebody check my math,
> Al
>
> On 7/9/2013 11:58 AM, W2HX wrote:
>> Hello all,
>>
>> I purchased a round, analog panel meter 0-30 ADC for a project. Printed
>> on the face of the meter says "FS=50MVDC" which I take to mean full
>> scale deflection will occur at 50 mV DC. Question is, can I get any
>> 50mV shunt (minimum 30A, of course) and will it work? Or does the shunt
>> need to somehow be 30A = 50mVDC? If I got a 100A 50mVDC shunt, will this
>> indicate incorrectly on the meter?
>>
>> Thanks in advance for the OT question
>>
>>
>> 73 Eugene W2HX
>>
>>
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>
> --
> Al Klase - N3FRQ
> Jersey City, NJ
> http://www.skywaves.ar88.net/
>
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