This circuit uses an MW radio tuned to around 540 kHz to detect atmospheric signals, for example, from an approaching storm. The circuit was taken from a Popular Electronics from the 90s.
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...