This test circuit was found in the PE Hobbyst Handbook in a 1990s edition. The circuit tests the battery under load. The load, as the battery is selected by the switch.
This Japanese radio is from the 60s, presenting excellent sensitivity and an output power of 100mW...
Found in a Popular Electronics from the 90s, this circuit uses components that are still current....
This circuit consists of a simple capacitance bridge. The handset can be high impedance from 500...