100 mA regulator (CB21168E)

This 2-terminal regulator was obtained from a 1990s National Semiconductor manual. The components admit modern equivalents.

Headphone amplifier (CB20653E)
The transistors used in this 1985 Radio Electronics circuit are for general use. The gain pot can...
Infrared detector (CB20976E)
This simple detector was found in Popular Electronics from the 1990s. Both the phototransistor and the PNP...
Regenerative circuit for two sensors (CB8266E)
Found in a 1967 American publication, this circuit with feedback for two transistors has a gain of...