on a very tight budget and little time to tinker, took an old cordless phone apart and found a way to signal from base to a remote handset with a series of beeps on page/locate, tried this link Radio Control Switch From Junk but can't get any predictable results from amp or transistor? how could i safely connect the speaker output to the arduino and let it analyze for a signal? i've seen several vox and sound activated circuits elsewhere but most still have unpredictable outcomes
you might be better off trying pulse dialing. most phones have a little reed relay in the base, when you press the number on the handset the little relay will click that many times.
trying for more of a rf signal transeiver, got some more searching done tonight and found this link http://coldsolder.files.wordpress.com/2010/04/scan0001-1.jpg stole some old pcb parts and built a simple cordless phone speaker to mic to arduino posibilty with good results, jus need to figure on how to direct link it all, working on pics, how do i safely, for arduino, go from speaker out of the old handset to a0 on the arduino?
got some fuzzy pics, first one is uno in the old sattelite box with lcd keypad tv out and pot, second is the coldsolder transistor amp conected to uno with speaker next to mic, third is the disasembled cordless phone mounted to tv dinner table
Neat idea. Detecting a speaker signal shouldnt't be hard. Put a diode in series with a 10 or 20k resistor and measure the voltage across it. I would think you could hook that to an analog input. Make sure the positive reading is at the pin and the other side to ground.
I think you could have ALL the buttons decoded if the handset was the remote and the base was the receiver and you decoded touchtones with a typical decoder chip. There can be 16 codes but most phones only do 12..
With a modern 2.4GHz wireless phone you could get a long range. Mine works over .5Km in the clear.
the batteries are plum shot on these phones so the only thing i can get any responce from is when they are directly connected to the chargers, i tried aa batteries with no luck, the only function i can get to work is the pager from base to the remote phone on charge mode, got the remote handset speaker wires direct wired to the amp/filter circuit, that provides a pulse to a 555 timer to stay on for about 5 secs to give time for a good trigger and time to get pager shut off this trigers another 555 timer to provide a relay toggle effect, now i get to hook the pager function from the base to arduino for control, don't have any 5 volt relays, so i'm experimenting with a moc3041 optoisolater, but it wants to latch the relay on when control is turned off, more learning to do 