Help us with fire and smoke alarm that will call a number

[pravardhan]

Guys, i and my friend are going to do a Fire and Smoke Alarm. I have the circuit for the alarms, but what we want to do is that when the alarm is triggered, we want to call a mobile phone so as to tell that there is a smoke or fire in the house.

So, could you people help us to make a circuit that can do this. using a microcontroller will be better. Or, do you people know any GSM based device that can send messages to mobile.

Thanks in Advance,
PRAVARDHAN

 

[elec-eng]

Need help urgently

you can do this using AT Commands

see the following linik




also search edaboard for AT commands
u will find a lot of topics

 

[pravardhan]

Re: Need help urgently

Thanks. But, I want a automatic telephone dialer when triggered circuit diagram. Using a microcontroller is best suited and should have a minimum of 2 trigger inputs.

I want the one just like this:
**broken link removed**
But, I don't want keypad & i want to store the number in the microcontroller.

Thanks in advance,
PRAVARDHAN

 

[cancel]

Need help urgently

try this **broken link removed**
look good for your apps

 

[boncker]

Re: Need help urgently

Did you try to make a wire between your alarm and your telephone? It is a few rustic, but can work good.
The output of the microcontroller you can drive until the telephone keyboard with diodes in series in each one wire. Then, connect each wire in each number contact. It will simulate a human finger in the keyboard. Also, don't forget to make a discrete output from your alarm to to take the phone off the hook. To do this I don't know but I think it won't be difficult.

Good luck.

 

[pravardhan]

Re: Need help urgently

Thanks boncker.

Well your idea is a great help for me. But, i still have a doubt that how to open/pick the receiver. So, should i go for a speaker phone or can i do it in an ordinary telephone.

 

[boncker]

Re: Need help urgently

I didn't understand very well when you say "receiver". Could you give me more details?

Sorry!

 

[pravardhan]

Re: Need help urgently

I mean its the place where the speaker and microphone is there. Its called the Receiver.

So, what do i mean is that do i have to put a relay to the receiver and the buttons?

 

[boncker]

Re: Need help urgently

Hi,

I would put some diodes in before the connection with the buttons to prevent some current return to the alarm box.
Also, you can put a relay in the ordinary telephone to the microcontroller take the phone of the hook and then dial the number to your mobile phone. You need to open the telephone and find the switch that "off hooks" your telephone. Like this:

- if the alarm sounds, the microcontroller sends a discrete signal to the relay to get the phone off hook.
- 1 or 2 seconds later the microcontroller dial the mobile phone by sending in discrete signals to your buttons. You can weld the diodes (1N4147 or similar) in the each button keyboard.
- the sound from alarm can goes directly to the microphone. Be careful with the signal amplitude and correct impedance.

See the file attached for more detais.

Note that I'm not sure how the off hook switch works, but may be easy.

 

[pravardhan]

Re: Need help urgently

Thanks. I will try to program and also to connect it to the telephone.

Currently, i don't have time to do & test it.