central call circut?

Question

How can I bulid a circuit that include a center with 2 rooms. If rooms want to contact with each other or with the center & viceversa, they should connect to center.(equipment:microphones,iphones and microswitches)
thanks

Answer 1

I use the vtech cordless phone, model # I6772. With it I can direct dial any of the other sets, 3 sets total. Found it at Target, quite reasonable. If you are more interested in building it, it isn't too difficult. Consider 4 wires, 1 is common (ground), one is voltage (-48vdc), one is Rm #1, one is Rm #2 (each room has 2 options to call) To place a call, apply -48vdc to the room desired (button or switch). -48vdc completes circuit through bell or buzzer. Pick up receiver to switch from bell in circuit to talk set in circuit. You don't need -48vdc, but if you do use it you can use a regular phone set. You could just use generic microphone and speaker in series, but feedbak becomes an issue unless you use a switch to cut the speaker when you talk. This only allows 1 talker at a time. Good Luck!