Split phone signal

[sebbeb]

Hi,

I need help with a project. I need to build a simple low budget phone conference system. Most of it is done. The last thing I can't figure oout is how to split the audio signal because on the phone, everything travels through the same two wires. I would like to be able to monitor what people on the phone say (In an earphone) without hearing the meeting. Any ideas?

Thanks in advance for your help, Seb

 

[MikeMl]

Google for "hybrid transformer" or "balanced hybrid"

 

[sebbeb]

Thanks you for your quick answer, that's all I needed.

Seb