This circuit is from a 1977 Radio Shack manual. The photocell is an LDR and the operational one is a 741. Components with non-standard values can be approximated.
This circuit was found in a Japanese documentation of the 70's. It uses transistors of the era and is...
The IC used in this project is not common these days, but if you have one you can build a high...
The frequency of this circuit is determined by the 1 uF capacitors. These components can be...