Bike speedometer (CB20497E)

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

Bicolor Sonic Sequential (CB17019E)
This circuit was found in a 1995 documentation. It drives a set of sequential LEDs from the sound...
Darlington Stage with Feedback (CB975E)
This circuit was found in a 1968’s publication and uses germanium transistors. Equivalents can be...
Linear Ramp Generator MC1455 (CB14585E)
The integrated circuit used is equivalent to the 555 and the transistor can be the BC558. R1 and...