If you have a common analog multimeter, you can increase its input resistance in the measurement of voltages for many megohms. The operational amplifier may be the 741 or equivalent and the power supplied by two batteries. Consumption is very low. If you have a common analog multimeter, you can increase its input resistance in the measurement of voltages for many megohms. The operational amplifier may be the 741 or equivalent and the power supplied by two batteries. Consumption is very low.
