Abstract: Disclosed is a voltage comparator circuit in which an input voltage and a predetermined reference voltage are compared by a differential amplifier to produce a signal corresponding to the difference between both the voltages. The width of a dead zone of the comparator circuit is established by an emitter-grounded transistor connected to the output of the differential amplifier, a polarity inverting IC gate connected to the collector of the emitter-grounded transistor, and a resistor which positive-feeds back the output of the IC gate to the base of the emitter-grounded transistor.

Abstract: In an electronic switching circuit using a junction type field-effect transistor, a capacitor is connected between the gate electrode of the transistor and a control pulse source. The capacitor is cooperative with a rectifying action of the gate electrode of the transistor to supply to the gate of the transistor a switching voltage which is different from the potential level of the control pulse from the control pulse source and is DC-restored following an input signal applied to the transistor.

Abstract: A sweep control circuit for an oscilloscope comprises a gate control circuit such as flip-flop which is applied with a hold-off signal from a hold-off circuit and latched by a trigger input signal, a free running control circuit such as NAND gate which mask-controls the hold-off signal to control a free running at an automatic sweep mode and a ground free running at a normal sweep mode, and a single reset circuit which couples a differentiated pulse signal to the hold-off circuit at a single sweep mode. To the hold-off circuit may be coupled a sweep stop made establishing circuit and a circuit for reducing the rise time of the hold-off signal.