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 spinner (see CB18894E) uses only an operational amplifier that must be powered by a...
The incidence of light in the LDR causes this circuit to start operating, emitting a sound whose...
This circuit is from American documentation. The components used are still common. The power...