rev counter and dwell meter

A rev counter and dwell meter is a useful service aid when setting up the ignition timing of a car, especially in conjunction with a stroboscopic timing light. The instrument described here will indicate dwell angle as a percentage of the complete timing cycle and will measure engine r.p.m. in two ranges that are selected aatomatically depending on engine speed. The circuit can also be used as a voltmeter for general checking of the electrical system.