Shunts

[PsychoMaster]

Hi Folk
I have bought some ammeters off Ebay that require 75mv shunts.Well the ones supplied are useless
to the meters and I am asking what resistance is a 75mv shunt? How did they come up with that,where is 75mv relevent? How do I turn this into ohms?
                            Thanks

[AlfBaz]

It'll be 75mV at x Amps. You then use ohms law. To find out how many amps it is put 75mV of the meter and see how many amps it reads

[DanielS]

An analog gauge has a full-scale current/voltage and the shunt is whatever resistance you need to have the meter's full-scale voltage at the desired full-scale current.

Use a low-current/voltage power source, step it up slowly until you get full deflection, subtract that current from your max range, divide the full-scale current by the remainder of the current, that gives you your shunt resistance.