We found this circuit in a 1967’s Electronics World. The circuit can be made with modern equivalent transistors. The selection is made by the tuned coil.
The presented circuit monitors a line indicating if it is busy if there is an extension. The...
July 2017 - The Texas Instruments step-down converter module of the same name IC can now be...
This circuit uses the LT6106 from Linear Technology, from where we took it from a 2005 manual....