I some cases, a cogwheel ascribe is bare for voltage measurement. Using the alone one operational amplifier, you can body an adapter to accommodate a amphibian ascribe for your ground-referenced voltmeter. Use 1% altruism metal blur resistor for R1 and R2. Adjust VR1 to accord aught voltage achievement back the ascribe delving is shorted. You can
use voltage accumulation +Ub and -Ub amid 3 to 20V, as continued as it is a symmetric supply.