Presettable integrating timing circuit

Claim 1

A presettable integrating timer, capable of comparing the time-volt product of an input with a preset signal, comprising: means, comprising an input and an output, for integrating an electrical signal at the input into an integrated signal at the output, the means for integrating being an operational amplifier (op amp) integrator; means, having two inputs, one input being connected to the output of the integrating means, the other input being connectable to a reference voltage, the means being capable of comparing the magnitude of a signal appearing at the first named input with the reference voltage, the means for comparing comprising an operational amplifier (op amp) comparator; means, connected to the integrating means, for clamping the input of the integrating means at a desired value; and a feedback circuit, connected between the output and the input of the integrating means to prevent the integrating means from saturating, the feedback circuit comprising a series combination, connected between the output and the input of the operational amplifier integrator, comprising a resistor, a diode, an emitter follower, another diode, and another resistor.