The Liskov Substitution Principle

An indicating potentiometer with a potentiometer having an input rotor rotatable through ten revolutions between internal limit stops of the potentiometer for setting the potentiometer output voltage, a rotary counter geared to the potentiometer rotor for displaying a readout of the potentiometer setting through an available counter readout range corresponding to the potentiometer voltage range, a manually settable drive shaft for simultaneously setting the rotor and counter and a pair of auxiliary resistors connected in series with the potentiometer for establishing an available potentiometer voltage range in accordance with the applied voltage and/or the desired counter readout range.