1536510 I C engine ignition systems MOTOROLA Inc 14 Dec 1976 [12 Jan 1976] 52131/76 Heading F1B In an ignition system in which a sensor means 22 produces an A.C. electrical signal about a D.C. electrical reference level established by means 23, 26, the A.C. signal being created in response to and having a frequency related to the engine rotation and being applied to a switching circuit 11, 12 having a D.C. threshold level equal to the D.C. reference level so as to produce a corresponding spark timing signal, selection means 31, 32, 33 are provided for rendering the threshold and reference levels unequal during running of the engine so as to increase the immunity to electrical noise while allowing the levels to be equal during engine starting to improve the accuracy of the timing signal.
展开▼
