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 May 1959 Radio Electronics magazine. Its purpose is to provide bias...
In the figure we have a circuit that fires from a positive pulse of short duration applied to its...
We found this alarm in a 1992 documentation. The circuit has several timings and the relay can...