We found this circuit in a 1957 Raytheon transistor publication. The circuit can be assembled with more modern transistors with minor changes. The handset must be high impedance magnetic.
Using the LM3909 this circuit was found in the January 1992 issue of Radio Electronics magazine....
This circuit was obtained in an old European documentation. The integrated circuit used is...
The circuit shown in the figure differs from the previous one (CIR8909) in that it can be...