Review on Comimark Microvolt Millivolt Amplifier Adjustable by Reynaldo Tong

This module has advantages over the AD620 equivalent implementation layout but is unsuitable for the very weak signals produced by load cell to load cell without modification. The gain potentiometer is 100kΩ, but load cells need a gain on the order of 500-1000 to provide a signal suitable for the ADC, and this requires a gain resistor of less than 100Ω for the AD620 chip. You cannot set the 100K potentiometer to these values. With some effort I managed to remove the 100kΩ gain potentiometer and replace it with a 100Ω part. Another solution is to parallel a potentiometer of appropriate value to 100kΩ and either leave it connected or use it to determine the correct value of the fixed resistor in its place.