This circuit for controlling high power LEDs (up to 2A) is from a General Electric documentation from 1970. The circuit serves to modulate a transmitter in PWM. The circuit serves as a shield.
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...