Abstract: Measured values are converted into electrical impulses for gauge devices and the like in a mechanism including a plurality of photocells arranged on a generally circular arc with a rotatable disc having angularly spaced radially extending slots arranged for movement relative to the photocells to energize and deenergize them in accordance with the angular spacing of the slots in the disc. Electrical circuitry operates to emit electrical impulses responsive to the energization and deenergization of the photocells and the photocells are mounted to enable their positioning relative to the rotational axis of the disc to be adjusted, thereby to enable adjustability relative to the emitting of the electrical pulses.