This circuit was obtained from the Encyclopedia of Electronic Circuits volume 5 of 1995. The circuit uses the 4001 CMOS to obtain hysteresis in the sensor feedback.
This variable oscillator with power step for alarms was found in an American documentation from...
This circuit was found in a 90s Radio Electronics. It produces an ultrasonic signal in a special...
This circuit is only used for resistive loads such as incandescent lamps. The bridge diodes can be...