Placed near a common receiver, this oscillator is intended to generate a beating signal to receive RTTY or SSB communications. The circuit is from old telecommunications documentation.
In the figure below we have two triggers made with the LM3900 transconductance operational...
We found this circuit in an English publication from 1980. It provides a logical output signal when...
This circuit was designed to work with the previous one in triggering a relay by the sounds picked up...