Discussion in "Electronics" started by    har    Nov 9, 2007.
Fri Nov 09 2007, 12:30 PM
#1
thanks for the reply

actually sir i wanted to do an project on security system with auto dial up circuit which plays the recorded message via telephone. hence i wanted the circuit details and telephone circuitory working fundamentals
regards
Fri Nov 09 2007, 02:20 PM
#2
there is a project using telephone interface in the download section.. take the circuit as reference.. and please do not create duplicate topics
Voice Ineractive System For College Automation project
Sat Nov 10 2007, 11:55 PM
#3
JUST TO REFER HOW TELEPHONE WORKS REFER THIS LINK
http://communication.howstuffworks.com/telephone.htm/printable
and this may also help as add on
This recorder can be connected to the telephone lines just about any place, and no external power source is needed. The tape recorder's switch terminals are applied to a pair of transistors, connected as Darlingtons, that are used to turn the recorder on and off. When the telephone is off-hook there's usually about 50 Vdc across the phone thats divided over R1, R2, and R4, so that Q1's base is negative enough to keep the recorder off. Pick up the receiver, and the voltage drops to 5 V. That leaves not quite-enough voltage on Q1's base to keep that transistor at cutoff, so the recorder begins. Remember to keep your recorder's switch in the on position, and depending on how many people use the telephone, remember to rewind or change tapes occasionally!
Sun Nov 11 2007, 02:15 PM
#4
a ring detector circuit.. might help you
 har like this.

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ExperimenterUK
Mon Apr 27 2015, 08:14 PM
@Janvier This project is in assembly. It is unlikely anyone has a 'c' code
Mon Apr 27 2015, 04:47 PM
Janvier
hello! can u help me to find c code for a project called " automatic light controller with visitor counter". Best regards.
ExperimenterUK
Mon Apr 27 2015, 05:27 AM
@mostfa.. it's a browser thing. Check your settings/try another browser.
Sat Apr 25 2015, 06:16 AM
rohan_verma
sir this circuit is tested?can i use it directly on developing PCB
Sat Apr 25 2015, 06:13 AM
rohan_verma
MSCOMM32.ocx cannot be copied in the systems folder even with administration rights.
Fri Apr 24 2015, 01:58 AM
mostfa
please fix the LCD Interfacing Tutorial as all pictures is gone
Fri Apr 24 2015, 01:57 AM
mostfa
LCD Interfacing Tutorial
Qasim359
Tue Apr 21 2015, 07:31 AM
hello every one i have made pic industrial and domestic timer and i can,t understand c code written in Hi-Tech please send me Mikroc code for this project anyone...................
ExperimenterUK
Wed Apr 15 2015, 05:07 PM
@Bibek.. and everyone. Create threads if you need help. The chat box is just for chat
ExperimenterUK
Wed Apr 15 2015, 05:06 PM
@mohd atif ..login..create a post/thread,then I can post a copy of the missing file

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i can,t understand C Code written in Hi-Tech pleas...
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