Simple current question.

[Richard9025]

Hi!

I'm building an ESR meter, a classic one with an analog microammeter for indication.

The problem is, the circuit is designed for a 50 uA microammeter. I only have a 200uA meter.

I get 1/4 full scale reading for 0ohms, shorted terminals (that's good because at 0 ohms means 50uA that is 1/4 of my meter's scale)

If I remove the "zero adjust" potentiometer and a series resistance, I can get a maximum of 110uA out of the circuit, but that is 1/2 of my meter's scale....

For full scale I need 200uA.

How can I increase the current to reach a full scale reading? By using some kind of DC current amplifier? Or maybe a voltage doubler?

I'll upload photos later, the question is simple: How can I adapt a higher amperage ammeter to work in a lower amperage circuit?

 

[Bluejets]

Might be an internal shunt you can change.

details on meter shunts here....... https://www.neatcircuits.com/meter-mult.htm

 

[(*steve*)]

Post the schematic. All that might be needed is a change in the value of another resistor.