Input positive or negative voltage, up to 15 volts, to positive side of op amp for upscale meter movement on 0-50 uA meter.
Use op amp with high slew rate and be aware high frequency may oscillate op amp and give erratic meter indications. The 10 uf capacitor is to by-pass AC voltages.
Variable 1k resistor is to use known DC voltage to set meter for accurate indications.
