Scientech Meter Back Amplifier

        The Back Amplifier is constructed on the processor Board. It was designed to match the resistance of the analog meter it replaces. Since that meter needed only 80 mv, emphasis was on low input offset voltage, as well as input bias current much less than 100 uA. This resulted in selecting a J-FET op-amp.

The gain needed to be stable, but any inaccuracy is correctable in software. It is 47.