This telephone recording circuit was found in the June 1979 issue of Radio Electronics magazine. The components are common at the time and the power is supplied by the power grid.
We found this junction tester circuit in an old English documentation. The circuit serves to check...
This circuit can generate signals up to 100 kHz. Found in documentation from the 1980s, it makes...
Found in American documentation from the 70s, this circuit uses components of the time, uncommon...