Saturday, July 26, 2008

Ring Detector for Caller ID Unit

Hi Friends,
this is an addition to the caller ID circuit of my previous post. For deciding whether call is received call or missed call, u need to monitor the ringing signal along with the off-hook detector signal, which is discussed in the last post. If the off-hook detector signal goes low (i.e. receiver lifted) before the ringing signal stops, then the call is labeled as received call, otherwise it is a missed call.
This small circuit converts the ringing signal (sine wave 90vrms) into 5v dc pulses which can be directly fed to microcontroller pin. The circuit outputs a pulse for each ring. The delay between two pulses is to be monitered and if it exceeds 4 sec, then ring is dead, hence, the call is missed call.!
Try it out..


gul said...


Nir said...


Could you send me the source code ? where i could download the source code.


CC Dharmani said...

Hi Nir,

I've sent you the code to read incoming DTMF signals from dialled number, in 8051 assembly language. the same routine can be used for received numbers, too.


Nir said...

It can recognise DTMF but not caller ID.
any idia?

CC Dharmani said...

hey Nir, what does that mean? is it able to recognise the dialled number but not the received number??

yu said...


Nice work

Could your send me the source code?



yu said...

Nice work
Could you send me the source code?



xray said...

hi sir,
i need to detect dialled numbers ring using controller.
plz send me the source code



please send me a source code.


please send me source code and schematics with at mega32.

Anonymous said...

hi sir could you please send me the microcontroller interfacing diagram of ringing detector circuit along with its source code.


its urgent sir.

Anonymous said...

sir, i must say... superb work
can u send me d code plzzz....


DJMIT said...

hi sirs
i am tring to interfacing sim 300 a gsm module to atmega16
sim 300 uses uart communication
so cam you plz help me out
can plz send me uart communication header file.
and if possible some help on how to go about it

panch dev parihar said...

sir i wanna interface the ring detector circuit with microcontroller .... plz send me the code for it...krishnaeec55@gmail.com

Anonymous said...

Hi sir,

I am getting the voice signal on the line after lifting the call. I am unable to detect the on-hook condition. Could u plz send the source code to detect on-hook in 8051.



Ruchi Bhargava said...

Plz send me the source code to read incoming dtmf signals from dialed number,in 8051 c language.

Willson said...

Hi Sir,

Can you send me a source code. Thank you so much.

asha said...

can u send me the source code.thank u my mail id r.ashargowda17@gmail.com

asha said...

how to detect the hook switch (ie on hook and off hook detector) i am doing project in epbax using avr controller in assembly language please help me any one .thank u

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It is an informative post.

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