I am doing a project that involves using a landline phone to work as the speaker and microphone for Skype calls. A representation of the final design is given below.
I have a landline phone in which I will remove all the internal circuitry. In this phone I want to build and add my own circuit. Only the headset of the phone will be used.
The mic and speaker of the headset, connected to an RJ9 connector will be first converted to a 3.5 mm mono speaker and mic connection. This will be connected to the PC using a miniature USB sound card.
When the user wants to use skype, he will dial from the PC and use the headset to converse. This much I can do. I also want the output from Skype to be routed to an external speaker (built into the phone case) if the user presses the Push-to-Talk button, thus enabling him to listen on to the conversation without talking.
Here is where I am stuck.
When the user puts the telephone headset down while on a call, I want the mic to be muted and the audio from the PC routed to the internal speaker in the telephone. To achieve this, I will have to switch the audio source from the PC from the headset to the external speaker. I am not able to decide how to accomplish this given that the amplification levels of the headset and speaker will have to be very different. Can anyone help me with selection of a set of IC's that will allow me to do the same.
I want the mic to be turned off when the telephone headset is put down while on a call in skype.
I will be using a microcontroller board for managing the IO's (mostly an Arduino Nano).