Telephone projects are fun. Imagine you want to make a telephone transceiver which can be controlled using microcontroller. A transceiver is device that can receive and transmit. This telephone transceiver can be easily converted to the automatic telephone transceiver. When the telephone comes in it is detected by the microcontroller and depending upon the user wish the call can be accepted or denied. Any microcontroller can be used. A port is available to connect to the microcontroller. The circuit uses opto coupler so as not to load the telephone line. The circuit consist of speech network that handles speech and amplification, noise cancellation. The output also consist of speaker and microphone output port to connect to speaker and microphone. The two outputs can also be connected to microcontroller. This is required if for example the audio signals are to be sent over USB or bluetooth etc.
Following picture shows the design of telephone transceiver for microcontroller based application.
This telephone transceiver is useful for any telephone based application. It is also useful for electronics engineering degree final projects.