Calling doorbell

[cheerio]

Hi,
a few years ago my doorbell died 3 times in about 5 months. The problem was that the button of the bell did not open sometimes and the coils of the bell did melt.
After a few weeks i kinda liked not having a doorbell so i did not repair it since then. And now my Girlfriend starts bugging me that i need a doorbell

So i think i make it a bit more complicated and funny

The plan:
If someone rings the doorbell it calls me on my cellphone.
If i answer the call i want to speak with the person at my door.
If i dismiss the call or it runs into a timeout it should tell the person that nobody is home ("the person you are ringing is currently not availaible" )
I can open the door by sending a code by sms to my doorbell.
As my girlfriend needs a ring too i need to call out on 2 lines simultaneously.

Status: nothing yet
MCU: Atmel Atmega8 (should do the job)
Phone: Siemens SL55 (got a lib to control the phone)

Problems:
Yet i got only 3 Problems.
First is that i do not know how to call on 2 Lines simultaneously.
Second is that i do not know exactly if i can connect the 2 doorbell signalcables directly to the microphone input of the phone (communication AND ringing signal uses the same 2 Cables).
Third and last until now is that i did never play back a soundfile with a MCU (i think i need to save the file on a SDCARD as tts would be such an overkill ^^)

Timeplan:
I try to start the project in August and finish it also in August. I got some other stuff going on but this project does not seem to be THAT heavy.



Please give me some feedback on how i can solve my problems and so on

[_pike]

i wish i could help you (about the programming section), but i use microchip.....
About your first problem i don't know if it is possible to be done by your network provider you can call them and ask them.if it is not possible then we should figure it out a tricky (smart way) of doing it.....
I can't understand you second problem,so please specify again your  concerns in more detail....
and for the last problem my cheap and not proffesional proposal is to buy a very very cheap mp3 player around  10-15$ and interface it with the mcu(after you have record your messages.)

[cheerio]

i wish i could help you (about the programming section), but i use microchip.....
About your first problem i don't know if it is possible to be done by your network provider you can call them and ask them.if it is not possible then we should figure it out a tricky (smart way) of doing it.....
I can't understand you second problem,so please specify again your  concerns in more detail....
and for the last problem my cheap and not proffesional proposal is to buy a very very cheap mp3 player around  10-15$ and interface it with the mcu(after you have record your messages.)

I like the idea with the mp3 player. i got an old one around somewhere.

About the 2cnd problem:
it has changed as i did mistake the telephonesystem cable as the signal cable. I can open the door and talk to the person outside over my home telephone. I think i can use this as an interface to my system. All i need to do is maybe levelshifting etc.

[kam]

a small message can be saved directly into the uC memory. This is something simple to do with a PIC 18, but i am not sure about AVR. The MP3 solution is also cool and simple.

[cheerio]

had no time for anything last month. and i received the Datacable for the cellphone just a few days ago.
maybe i finish it this month

[cheerio]

Laziness won in September again
I did some measurements and the system is working on avg. 12V AC.
I found some information @Siedle the manufacturer. I do not know the Systems Model but i found out that the Phone i try to hack/replace is the HT411-02

1. Milestone will be:
Call me on my mobile when the doorbell rings.

This should be an easy task

[cheerio]

After some month i picked up the project again.
status:
communication between mcu and the phone is working well. i am working @ some extra features now.

Phase:
prototyping

[cheerio]

I encountered a problem i could not solve yet:
When i use the Light switch of another room (the light is switched on by a AC relais) i get these spikes on my circuit.
The MCU thinks someone rings and calls me...
I think the best way to solve this is to filter the spike out but i did not succeed with capacitors etc.

Does anyone know how to handle it?

[kam]

oh well, i know one person who got a headache from this. I suppose that the light is either ccfl or similar correct? This indeed has enormous amount of noise. One solution is to make a filter with capacitors and an inductor.  This is typically how it goes: One capacitor is parallel to the supply, then the inductor goes in series with the positive supply, then a capacitor again parallel to the supply but from the other side of the inductor. You may find this as U filter or Π filter in greek letter. Try an 100uH inductor but if you have problems you may need to increase it.

If this do not work for you, then you can filter the AC line with some sort of EMI filter (for example http://www.murata.com/products/catalog/pdf/c09e.pdf)

[cheerio]

the lights are not the problem at all. The spikes are emitted by a relay
i think i try the emi filter as i do not have many inductors at home.

[kam]

You can make an inductor for test - it is very simple. Get an iron core or ferrite and wind some wire around, the wire with the paint cover used for motor windings. Some 100 turns are enough. Just for test.
Or you can use the secondary winding of a transformer, which has thick wire with few turns. Also ok for testing.

[cheerio]

I remebered that i salvaged some PC PSU! i am pretty sure i find some inductors on these.

edit:
Does not help much... ~0.5V less peak but this is marginal...

[kam]

i bought once some voltage suppressors for such situations, but i never used them.
How much current you need to provide though the filter really?

[cheerio]

Theoretical the current peak is 2A. But in reality it is ~0.5A

[kam]

and what sort of power supply you use? and the input how is coupled (for the ringing signal)