Abstract: A timing circuit utilizing first and second hysteresis comparators. The first comparator senses the voltage across a capacitor in a first charging circuit. Whenever this voltage exceeds the high comparator reference level, the comparator output is at a first voltage level, permitting charging of the capacitor. When the capacitor voltage drops below the low comparator reference level, the comparator output switches to a second level, discharging the capacitor at a rate much faster than the charging rate. The second comparator interacts with a second capacitor in similar fashion; however, the second capacitor is permitted to charge only during the discharge periods of the first.

Abstract: A first transistor of a first conductivity type connected as a common-base amplifier in the collector-to-base feedback connection of a second transistor of a second conductivity type, complementary to the first conductivity type, exchanges base current with a third transistor of the second conductivity type. The collector current of the third transistor is proportional to that of the second transistor by a factor substantially equal to 1/h.sub.fe, where h.sub.fe is the common-emitter forward current gain of the first transistor.

Abstract: A micropower, latch-up free, relaxation oscillator includes a switch such as a programmable unijunction transistor or a silicon-controlled-switch. The switch is coupled at its gate electrode via an emitter-follower circuit of low output impedance, to a source of reference potential provided by a relatively high resistance resistive voltage divider. The condition of the switch, whether conducting or not, is controlled by a resistor-capacitor timing circuit. When the capacitor charges to a given level, it causes the switch to conduct and to act as a discharge circuit for the capacitor. When the capacitor discharges to a second level, the switch goes off and the cycle then repeats.

Abstract: Clock pulses for a counter and trigger pulses for a thyristor switch are derived from the axis crossings of an alternating current signal. Logic circuits responsive to the counter determine the total number of trigger pulses supplied to the thyristor subsequent to a control signal transition or, in the alternative, delay application of the trigger pulses until a given number of axis crossings have occurred.

Abstract: An input terminal is quiescently biased to a voltage closer to the initial threshold setting of a first comparator than to that of a second comparator. In response to the proximity of an object, an alternating voltage is induced on this terminal of an amplitude to actuate only the first comparator. Each time a comparator is actuated, a two state circuit changes the threshold settings of the comparators to bring the one formerly outside of the range of the alternating voltage to within its range and vice versa.

Abstract: a threshold current gate provides a diversion path for substantially all input current lower than a threshold value applied to the trigger electrode of a switch, such as a semiconductor controlled rectifier (SCR), thereby inhibiting switch triggering. When the input current exceeds the threshold value, that portion which exceeds the same flows into and triggers the switch.