Bike speedometer (CB20497E)

This circuit can be powered by a solar cell. The circuit is from a 1991 documentation having a phototransistor as sensor.

Digital Code Switch (CB18221E)
This circuit activates an output, which can be a lock, only when a card containing the programmed code...
Inductive Signal Follower (CB12176E)
This circuit was found in Popular Electronics from 1993. The 1458 consists of a double 555. The...
Shift Register Using the 4013 (CB156E)
This is a Serial In - Parallel Out or Serial Out [SIPO or SISO] shift register using the...