How to use a GSM based mobile phone to control a circuit,say alarm circuit?Can it be done like this(block dia):
GSM phone->GSM receiver->Microcontroller->Alarm circuit.
If yes, which GSM receiver and uC can be used?

 

Ooh...posting in this forum has become really tough since the last time(a year ago) i logged in.Is there any limit to the no. of characters allowed?

 

There might be some limit but I've never hit it. What problem are you having?

Your question sounds a lot like a remote bomb trigger.

Why not just use an old cellphone to receive the signal and sound the alarm?

 

I was not able to post until i trimmed down the sentences
When i searched using google, i found a post in this site where they say a character limit has been implemented.
Back to my question.
The signal receiving section must be as small as possible so that it can be attached to a object. Old cellphone is too big for such an application.
The idea is too remotely activate an alarm circuit attached to a object using a gsm cellphone and hence track it.
A simple one. Don't laugh at me.

 

Old cellphone is too big ...

Well, it's not like they make those bulky on purpose. You need a battery for one thing. How big a device are you hoping for? With no need for a keyboard or screen, I suppose a stripped down cellphone could be made smaller. But you'll need a way to program your device, which will need to have a cellular service plan. Sounds like a very complicated project. But don't let my ignorance discourage you.

 

But you'll need a way to program your device, which will need to have a cellular service plan. Sounds like a very complicated project. But don't let my ignorance discourage you.

When i make a call to the SIM, a signal generated by the SIM should be able to control a siren. I feel that this can be done using a transistor as switch configuration or should i use a microcontroller.
This is a novice kind of a project. Not able to understand the complications.Confused

 

You don't make a call to a SIM, you make a call to a cell phone with a contract with a cellular carrier. And while you don't need for the "GSM receiver" to talk back to you, it has to transmit constantly to the cell network with its status so the network knows where it is in case it gats a call.

There are industrial cell devices without the case, keyboard, screens, etc. But you still need to power it, an antenna, a way to program it, and a cell plan to get to it. And they are expensive if you can even find one. I used one from Motorola 14 years ago, but they dropped the product line soon after.

Nothing will get you what you want in a small, cheap, portable package except a small, cheap cell phone.

ak