How to scale a micro ammeter? Answered

I need to measure the current of a Tesla coils secondary output and have found that it is under 1mA and above 50uA so how can I scale a 50uA DC micro ammeter or a DC milliammeter (can't remember its range) to the appropriate range?

Tags:milliammeter micro ammeter Tesla coil

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rickharris

8 years ago

This should answer your question - you will need to shunt some of the current round the ammeter mechanism.

Dr.Bill

Answer 8 years ago

Ya know, "This" , is very good to have around as a refrence so I copied it.

http://www.allaboutcircuits.com/worksheets/meters2.html

iceng

8 years ago

You can always use a resistor and Steve's favorite tool a scope
even a mili-voltmetre.... and math.

Alos, a pick axe and rope can help you scale the difficult domains :-)

A

steveastrouk

8 years ago

The meter SHOULD specify its resistance. With that, you can work out the shunting resistance you need.

I = I_meter x G_meter + I_shuntx G_shunt

I is the total current flowing.
I_meteris the current in the meter.
G_meter = 1/R_meter
I_shunt= current to flow in shunt = I-I_meter
G_shunt= 1/R_shunt.
Rearrange for G_shunt.

Steve

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How to scale a micro ammeter? Answered

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