This circuit was found in a RE Experimenter Handbook from the 90's. The components are of the time, rare nowadays, except the 555 and 4017.
This sensitive photo-diode circuit with output compatible with TTL logic was found in a 1972 RCA...
The circuit shown uses an operational amplifier that is uncommon nowadays. The circuit was...
The 2N3055 transistors in this powerful power supply must be mounted in excellent heat radiators. The...