This commercial radio for the AM band was sold in Japan in the 1960s. The circuit has an IF of 455 kHz and is powered by batteries. The push-pull output gives a good audio power.
In the figure we show how to activate a relay from the output of a common operational amplifier when...
Found in a publication from the 50's, this circuit uses a germanium transistor of the time. The...
November 2016 - Mouser Electronics already has the Arduino Shield 101 for IoT applications with...