This circuit, found in a 1958 magazine, is for reference only, since the components are not easy to find today. The transistors are germanium types and power supply is made by common cells.
Often, unauthorized people use the phone to make improper calls. A control for this is achieved with...
This circuit was obtained in an Electronque Loisirs magazine from France, in a July 1991 edition. It...
This circuit sensor is an NTC with a resistance of the order of 2k. The SCR can be from the TIC...