Voltage regulator (T455E)

This positive feedback voltage regulator was found in the 1950s MIT documentation. The circuit allows you to adjust the output voltage.

Door buzzer or alarm (CB20492E)
This solar powered circuit was found in a 1991 documentation. The transistor is a general purpose...
PGA460 and PGA460 Q1 Ultrasonic Processors and Driver
August 2017 - Mouser Electronics is in stock with the PGA460 and PGA460 Q1 ultrasonic processors...
Light Beam Operated Relay (CB4956E)
This circuit was found in an old American magazine and could make use of more modern components...