Electric cranking motor automatic disconnect and lockout circuit

摘要

The output signal produced by a two input electrical circuit element of the type which produces opposite polarity output signals upon the application of the same polarity input signal to respective ones of the input terminals is applied to the control electrode of a switching transistor which, when conductive, is effective to complete the energizing circuit of an internal combustion engine cranking motor. An electrical bias signal of a selected polarity is applied to the one of the input terminals of this circuit element which will result in an output signal of the polarity which will trigger the switching transistor conductive through the current carrying electrodes thereof. An engine speed electrical signal of the selected polarity and of a magnitude directly proportional to the speed of an associated cranked internal combustion engine is applied to the other input terminal of this circuit element whereby when the engine speed has reached and exceeds a predetermined magnitude, the output potential signal of the circuit element is of a polarity which will extinguish the switching transistor to interrupt the cranking motor energizing circuit.