Found in a 1924 publication, this 2-valve receiver has a speaker output. Power comes from several batteries. Information about the coils is given.
This circuit was found in the July 1992 issue of Radio Electronics magazine. The circuit is based...
This timer activates a relay after a time interval of up to 15 minutes has elapsed, starting from...
The circuit presented is based on a mechanical tuning fork. The circuit is suggested by National...