So, this semester project was this: a device has an input. The device"listens" to the input. When there is sound on the input it waits, and when the sound leaves, it closes and opens a relais module.
Where this device could be used for? Do you have any idea?
Thank you...
Both seem possible. You may wonder how many weird looking projects serve some serious purpose in real life.
A good engineer should always check the specs given by a customer of unknown skills. You are one a good way with your question 
alex5678:
Where this device could be used for? Do you have any idea?
Maybe thats the point of the exersize, you have to work it out ?
srnet:
Maybe thats the point of the exersize, you have to work it out ?
I am on the point of completing it, but I cannot figure out, where is its usefullness...so I thougt of asking here, in order to get opinions of more experienced/professionals..
Thank you...
The most obvious use of the system should be that it can help giving you a passing grade.
As soon as the telephone rings, you will see the answer in the form of SMOKE!
Paul
a device has an input, that connects to telephone line
Isn't this illegal?
Isn't this illegal?
YES
Mark
holmes4:
florinc:
Isn't this illegal?YES
Mark
So my modem is illegal?
It very well may be. Check your local laws and regulations.
Why is it illegal?
alex5678:
Why is it illegal?
Do you want to be the one to find out why attaching home-brew equipment to the public phone lines is a bad idea?
I can't take the explanation for what the project does literally as it's just too loose to do that.
It's likely something cooked up to include certain elements, a full app at both ends would be a lot more work.
alex5678:
Why is it illegal?
To protect the equipment that the phone companies have and maintain.
To prevent injury (or death) to the engineers working on the telephone network or other users.
To prevent interferance with other users of the telephone network.
There is, in most places in the world, a requirement to have equipement connected to landline networks tested and approved.
All very obvious I would have thought ..................................
Connecting to telephone line is my hypothesis, I am not sure connecting in telephone line. But it will be activated with sound...from mic for example..
For example, this use of the word "connect" and the use of the words "I am on the point of completing it" don't make sense to me in the context they've been used.
However this project does remind me of descriptions of what phone hackers do, get a signal then wait and send one. Long ago there was a whistle in boxes of Capn Crunch Cereal that used at the right time set up a maintenance mode that allowed free long distance calls at least from pay phones or maybe smart hackers wouldn't do that from home.
got a link to what sound 'over 0,5Vpp' makes ?