GROUND PICK-UP TACHOMETER

摘要

A ground pick-up tachometer for detecting a rotational speed of an engine in a vehicle includes a probe (12) arranged for connection to a vehicular ground to detect signals emitted from an ignition system of the engine. A tachometer circuit is operatively connected to the probe (12) to identify the detected signals representing ignition sparks and provide output (30) representative of the rotational speed of the engine based on the identified signals. The tachometer circuit includes a circuit common reference, separate from the vehicular ground.