This circuit was found in a 1980s documentation but can be easily assembled even today by the components it uses. The circuit reproduces what is said in a telephone conversation functioning as an extension.
Devices Feature Open Immobilizer Protocol for Interoperability and Low Frequency Vector Techniques for...
This circuit is from an American 80's documentation. The integrated circuit is from the time and...
The frequency of TTL square signal is divide by 5 with this circuit. Power supply is 5 V and the...