This circuit emits a warning sound when night falls. The circuit is from a Hands On Electronics from the 90s. The Sensor is a common LDR and R6 adjusts the trigger point.
This circuit was found in Motorola documentation from the 1980s. PUTs are not common components...
This low distortion circuit was found in a 1964 Electronic Design. The transistor admits...
This circuit is based on an uncommon Texas component today, as found in an American 1980s...