Solar flashlight (CB20488E)

This circuit charges a battery to power a flashlight at night. The circuit is from an English publication from 1991.

1 kHz Notch Filter with the 741 (CB12287E)
In this circuit, from a 1977 publication, we have the traditional version of a filter that rejects 1...
Voltage Controlled Current Source 3900 (CB19706E)
The integrated circuit used in this application is uncommon today. However, the basic...
Servo Control (CB5941E)
This physical line servo control uses components that are not currently common. The circuit is from...