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.
The presented circuit makes use of a operational transconductance amplifier (OTA). We found this...
This circuit uses a not easy to find IC these days. The circuit sources 15 W to a 4 ohm load and...
Found in American documentation from 1968 this circuit is based on discrete components in addition...