This radio for the AM band has the traditional superheterodyne configuration with several transistors and integrated audio amplifier circuit. The circuit is from the 70s.
Found in a Popular Electronics from the 90's, this circuit detects the approach of objects by the...
This old 4-channel circuit was found in the December 1994 Electronics Now magazine. The circuit uses...
The figure shows how to implement an alarm buzzer in an LM3914 to warn about crossing the scale...