18-11-2015, 05:06 PM
Those old instruments are lovely. It must be difficult to get those standard batteries these days.
In modern times they use a very special silicon device to get the voltage and a couple of OP amps in place of the potentiometer.
Later the manufacturers wrapped the galvo and power supply up in a single box and used the same principal in order to measure resistance.
This does not even need a regulated power supply as it is measuring the ratio of the resistors and not the absolute value.
I have got one that in built into a Megger.
In modern times they use a very special silicon device to get the voltage and a couple of OP amps in place of the potentiometer.
Later the manufacturers wrapped the galvo and power supply up in a single box and used the same principal in order to measure resistance.
This does not even need a regulated power supply as it is measuring the ratio of the resistors and not the absolute value.
I have got one that in built into a Megger.
