This sensitive circuit was found in an Electronics Hobbyists Handbook from the 1990s. The circuit can use common general-purpose transistors in place of the original ones.
This circuit was taken from the 1960's Mullard Transistor Manual. Information about the coils is...
This bridge circuit is designed for 8-ohm speakers delivering a few watts of power. The circuit is from...
This alarm, from a 1996 magazine, can be fitted with two BC548s in the original configuration...