Hi. I'm a totally noob, I've done some online "demo" projects but I want to try my own.
My grandma has an old wired phone at home. She often forgets to hang it properly so we can't contact her until she realizes.
I've thought about hacking it so when the phone is unhooked for too long (maybe 3h) it makes some sound.
The problem is that I can't think of a way to connect the phone to the Arduino. I know that when you pick it, there's a switch that activates everything. Also a led light turns on.
So how can I read the phone signal? There's any way to remove the led or connect the switch to the Arduino "in the middle" so instead of turning on the led, the Arduino gets a signal?
Add a switch that breaks the connection, effectively hanging up. This has to be done after the ringer so it will still ring.
Then add a vibration switch to the handset, so it knows when she's picked it up.
Your telco probably wouldn't appreciate you interfering with the phone signal.
Instead, why not either use an optical interrupter, or a reed switch and a magnet on the handset? Either of those could be wired to the Arduino to alert it to the phone being off the hook, and it's a simple bit of code to add a running timer that, upon timeout, rings a bell until silenced by the phone being hung up again.
C
There will be 50v or possibly 60v across the line when the phone is idle, either polarity. Ringing is AC on top of that. Probably 10v to 20v off hook. All that and balanced too, so you have to be careful not to unbalance it. A complete pain to work with. Do as others have suggested, build something separate.
Traditional analogue phones are being replaced by VoIP by 2025 in the UK, I think similar in other countries, so if you do hack the phone now you will have to do it again in a couple of years.
The phone company sends a wailing tone down the line after extended off hook time.
Buy her a simple, big button, cell and forward her landline to it so she doesn't have to change numbers.
So the first question here, is whether her phone is indeed, on the "traditional" Analog system.
If it is, does it not have the "howler" function? And how persistent is that?
If it is already digital or as we are in Australia, "NBN", then the phone is connected to a local VDSL modem, is not powered at 50 V but 24 V, and the telco does not actually care greatly what you connect to the FXS port on the modem.
The howler on mine is only brief, intended to remind you while you are still near.
Very practical, using the "Forward if busy" function on the POTS.
Hi guys! thank you for your answers. I don't know how to quote you so I'll do a general answer.
My original plan was to make an external circuit and just tape the components to the phone. I already have a reed switch so I did some testing and it won't work because my reed switch activates at like 1.5inches but my grandma sometimes misses for 1/8th.
I've also thought about just gluing a button but the slimest I've found would interfear too much.
I don't like the idea of modifying the phone circuit either and I've never used a hall effect sensor before. Are they sensitive enought? I have to buy it anyway so, sugestions?
HI,
Ring your telco, find out if they have such a device that can be connected the phone.
You will be surprised what the telecom world has to offer disabled and forgetful grannies.
AND/OR
Ring your countries disabled persons department/organisations to see what is available.
Find others with the search phrase: "detect telephone off hook circuit"
Use an opto coupler if you want to connect such circuits to an Arduino.
My POTS connection is derived from the broad band router. The router itself has a glass fibre connection to the provider's network.
