This circuit is from a 1990s publication by William Sheets. The circuit consists of a stage whose gain is adjusted according to the signal intensity.
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...