[Boatanchors] general OT question on panel meters

[Al Klase]

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/