This circuit is from a 1968 documentation using one of the first integrated circuits available at the time, the TAA370. The circuit is powered by 1.3 V using a 200 ohm handset.
The BFO or Beat Frequency Oscillator is used to receive telegraphic signals or even modulated in...
Taking advantage of the comparator setting, we can use the Norton amplifier as an over temperature...
This circuit was found in an American documentation from 1975. The components of the time can no...