Obtained from an English publication in the 1980s, when a weather station operated in that country at 60 kHz, this circuit employed only two general-purpose transistors.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...