There seems to be a number of ways of achieving this solution.
Up until now I have used a zener in series with the meter and calibration resistor, with a second resistor in parallel beforehand to control the zener firing voltage and a third high wattage resistor in either suply leg to limit the power.
I now wonder if this is far too complex, because it takes ages to balance the circuit. It also ends up with poor linearity.
Maybe a straight forward zener would do, with the calibration resistor. Use a 1mA movement and back the bottom bridge off so it operated from 0.7 to 1.7mA. That should make sure the zener fires okay.
Has anyone got any comments or suggestions on a better solution?
many thanks
Up until now I have used a zener in series with the meter and calibration resistor, with a second resistor in parallel beforehand to control the zener firing voltage and a third high wattage resistor in either suply leg to limit the power.
I now wonder if this is far too complex, because it takes ages to balance the circuit. It also ends up with poor linearity.
Maybe a straight forward zener would do, with the calibration resistor. Use a 1mA movement and back the bottom bridge off so it operated from 0.7 to 1.7mA. That should make sure the zener fires okay.
Has anyone got any comments or suggestions on a better solution?
many thanks