ok let me show you a few things, this way I can run through the idea in full
ok so the row of buttons to the right of 1-6 are the WIP's. I want to pick up the receiver one end and call the receiver on the other. that receiver will ring until picked up then talking is established. when the button is pressed again I want the connection to be cut.
however if they pick the phone up on the other end the little light will flash on this board and the phone will ring IF we aren't already on another call until we press the button and establish a line or they hang up.
as this is for training I was going to have maybe 5metres between the "EWIS" and the "WIP" thus using 1 power supply of 12volts.
I am currently in the process of making a system but am thinking it might be easier with old chorded phones, but then I need a 90vac supply at 20hz.
I got to thinking about what a phone was and thought how about making my own cheaper. so have gotten a few awesome things of ebay to take control of the system. first I will use
http://www.ebay.com.au/itm/14126485...e=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649this will be my naughty red phone. I designed a double ended circuit for the ringers and pick up thingy using 2 amplifiers for communication
http://www.ebay.com.au/itm/141110093047?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
the ringers I will make myself. so at this point I will use about 6 wires.2 for speaker to mic, mic to speaker and the ringer circuit.
I am then going to use another amp and speaker for the PA system, and then using 2 arduinos organise the actual alarm noises. so all up bout 500billion wires... or 10 if I am lucky.
if you want drawings let me know and kris if you got me on chat still I can PM you further details. just let me know if you can think of an easier way.