How do I measure it? Is it enough to measure it with the multimeter? I worry because the multimeter may cause huge deflection as you measure the resistance and may burn the precious meter?If we assume your 100uA meter is 100 ohm R,
With an instrument or circuit that is guaranteed not to exceed 100 uA. Might be a multimeter with manual range select, or a combination of voltage source, series resistor and mV meter.How do I measure it?
With an instrument or circuit that is guaranteed not to exceed 100 uA. Might be a multimeter with manual range select, or a combination of voltage source, series resistor and mV meter.
Regarding shunt temperature coefficient, consider that the meter has also copper coil and respective copper T.C. A thick copper shunt that doesn't heat up and tracks the meter temperature will probably give best overall accuracy.
Which scale should I select in the manual meter?
And don't forget you can use a combination of shunt and series resistances. A shunt to bypass most of the current and a resistor in series with the meter to limit how much of the remainder you measure.
It really depends on how much voltage you can afford to lose in the shunt. If for example it is in the input of a voltage regulator, you can probably afford to use a much higher value because the regulator will keep the output voltage steady anyway. If it is after a regulator or in say a battery feed, you probably can't afford the voltage drop so the value has to be as low as possible.
Brian.
And don't forget you can use a combination of shunt and series resistances. A shunt to bypass most of the current and a resistor in series with the meter to limit how much of the remainder you measure.
It really depends on how much voltage you can afford to lose in the shunt. If for example it is in the input of a voltage regulator, you can probably afford to use a much higher value because the regulator will keep the output voltage steady anyway. If it is after a regulator or in say a battery feed, you probably can't afford the voltage drop so the value has to be as low as possible.
Brian.
Feed ---------> shunt resistor ---------> load
----> pot ---> 100ua Meter ----
If I calculate it right it needs a shunt of 0.136 ohm.
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