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General Category => Your projects => Topic started by: cheerio on July 13, 2011, 14:13:16 PM

Title: Calling doorbell
Post by: cheerio on July 13, 2011, 14:13:16 PM
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" :D)
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

Title: Re: Calling doorbell
Post by: _pike on July 13, 2011, 17:28:21 PM
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.)
Title: Re: Calling doorbell
Post by: cheerio on July 13, 2011, 17:58:55 PM
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.
Title: Re: Calling doorbell
Post by: kam on July 13, 2011, 18:35:39 PM
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.
Title: Re: Calling doorbell
Post by: cheerio on September 02, 2011, 15:52:11 PM
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
Title: Re: Calling doorbell
Post by: cheerio on October 14, 2011, 03:28:25 AM
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 ;)
Title: Re: Calling doorbell
Post by: cheerio on March 23, 2012, 11:50:10 AM
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
Title: Re: Calling doorbell
Post by: cheerio on April 04, 2012, 22:12:50 PM
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?
Title: Re: Calling doorbell
Post by: kam on April 05, 2012, 15:24:58 PM
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)
Title: Re: Calling doorbell
Post by: cheerio on April 05, 2012, 16:19:44 PM
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.
Title: Re: Calling doorbell
Post by: kam on April 05, 2012, 17:02:55 PM
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.
Title: Re: Calling doorbell
Post by: cheerio on April 05, 2012, 18:23:28 PM
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...
Title: Re: Calling doorbell
Post by: kam on April 05, 2012, 20:25:08 PM
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?
Title: Re: Calling doorbell
Post by: cheerio on April 05, 2012, 20:36:49 PM
Theoretical the current peak is 2A. But in reality it is ~0.5A
Title: Re: Calling doorbell
Post by: kam on April 05, 2012, 21:52:41 PM
and what sort of power supply you use? and the input how is coupled (for the ringing signal)
Title: Re: Calling doorbell
Post by: cheerio on April 05, 2012, 22:26:03 PM
i am using a switch mode psu. 230vAC -> 5vDC
The ringing signal is 12vAC and completely decoupled by a relay. If the relay is activated it connects the 5vDC of my circuit to a pin on the MCU.

i will buy another switch mode PSU which might solve the problem. 5€ is worth a shot
Title: Re: Calling doorbell
Post by: George on April 06, 2012, 01:42:08 AM
Another method is to put a transorb diode on the DC input to filter out the spikes
Title: Re: Calling doorbell
Post by: kam on April 06, 2012, 07:46:30 AM
i will buy another switch mode PSU which might solve the problem. 5€ is worth a shot

or you might try a linear supply with transformer?
Title: Re: Calling doorbell
Post by: cheerio on April 06, 2012, 14:04:14 PM
this would be too big. the casing is pretty flat
Title: Re: Calling doorbell
Post by: kam on April 06, 2012, 15:54:33 PM
this would be too big. the casing is pretty flat

so you use a flyback SMPS from 220 directly to supply right?
Title: Re: Calling doorbell
Post by: cheerio on April 06, 2012, 16:52:46 PM
i use a 9V smps, a 5v fixed voltage reg. and some caps to ensure a stable voltage. The new smps would deliver 5V DC / 2A out of the box.
Title: Re: Calling doorbell
Post by: kam on April 06, 2012, 17:16:48 PM
i use a 9V smps, a 5v fixed voltage reg. and some caps to ensure a stable voltage. The new smps would deliver 5V DC / 2A out of the box.

but the smps gets power directly from 220V?
Title: Re: Calling doorbell
Post by: cheerio on April 06, 2012, 20:08:13 PM
yes
Title: Re: Calling doorbell
Post by: kam on April 07, 2012, 14:13:33 PM
so it is probably a flyback SMPS. is it possible that you do a test with a PC supply?
Title: Re: Calling doorbell
Post by: cheerio on April 07, 2012, 18:30:12 PM
All the PC PSU i own have Voltage spike filters, so it would solve the issue. But they are too big ^^
If the new PSU does not fix the problem i will salvage a filter from an old PC PSU.
Title: Re: Calling doorbell
Post by: kam on April 08, 2012, 13:26:20 PM
That is what i wanted to confirm. most probably a voltage suppressor and some sort f filtering at the input will work pretty well for you.