Using 4 tubes, this 1924 receiver combines new technologies as an intermediate frequency stage that was already beginning to appear. Listening is via phone and battery power.
This triac circuit was taken from an article in the July 1970 Radio Electronics magazine. Note the...
Signals ranging from a few millivolts to a few volts can be used to excite a relay with this...
This circuit was found in American documentation from the 90's. The transformer determines the...