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 components of this circuit are exchanged for modern equivalent such as 470 K for the pot and...
This watt meter was found in an old telecommunications documentation. The circuit is interspersed...
This sensitive receiver with earphone was found in an English documentation from 1963. The...