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.
With this circuit it is possible to obtain an input resistance of 100Gohms for a multimeter, with...
This amplifier, to detect biological signals in implanted transmitters, uses transistors such as...
This application is not modern since few computers have parallel ports. But you can use this...