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 1987 circuit uses a common ignition coil to generate high voltage to power a fluorescent lamp that...
This circuit is from the American magazine that no longer exists Science & Electronics,...
This circuit is from a 1975 technical documentation on filters. The FET can be a BF245 and the...