This circuit is tuned to reject stations of different wave bands that may be interfering with the reception of short waves.
Featuring low output impedance and high input impedance, this configuration was found in a 1980s...
In the figure we have a TTL logic interfacing circuit as CMOS logic using a 6N139 optocoupler...
We found this circuit in an English documentation from 1989. The integrated circuit used is not...