Need help for my project

[Jemencrisse]

Hi
I'm new here and I tru to receive some help to achieve a project.
I work in a companies where everyone use phone constantly and I want to build a kind of busy light.
My goal is to install this between the phone and the headset.
So here what is my idea.
A little circuit with 2 female rj11 connections and a power 110v in and out.
A soon as we detect a tension on the line, this trun on and let 110v passe. (This will open the light)
In fact I wish to have a circuit that will be a switch that turn on if its detect tention.
I think the best way to do this is mosfet but any idea will be really helpful
Did some one can help me with this?
Thanks for you help.

 

[audioguru]

Do you want to detect DC between the phone and the headset? There is no DC, instead it is AC audio at a fairly low level.
The AC audio varies in level so if you make a circuit that turns on an LED when it detects audio then the LED will sometimes be turned on and between spoken words it will be turned off.

 

[Jemencrisse]

Thanks for the reply,
My goal is to create little circuit that can be place between phone and headset and who will light a light when someone is at the phone. The reason I want to place it between the phone and the headset is because we use ip phone.
Do you have an idea to do this?
Thanks by advance.