Discussion in "Electronics" started by    har    Nov 9, 2007.
Fri Nov 09 2007, 07:30 AM
#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, 09:20 AM
#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, 06:55 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, 09:15 AM
#4
a ring detector circuit.. might help you

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Please post questions in forum
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ExperimenterUK
Sat Aug 16 2014, 04:16 PM
@diligent . create a thread
Sat Aug 16 2014, 03:17 PM
diligent
in assembly langauage programming..
Sat Aug 16 2014, 03:14 PM
diligent
will anyone help me?

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siddique Avatar
Posted By siddique
Sat Aug 30 2014, 03:34 AM
Have you tried using the TX setup to receive and v...
ExperimenterUK Avatar
Posted By ExperimenterUK
Thu Aug 28 2014, 03:31 PM
So, I don't think there is any need to load any da...
ajay_bhargav Avatar
Posted By ajay_bhargav
Thu Aug 28 2014, 06:33 AM
Did your professor ask this question to you? I sug...
siddique Avatar
Posted By siddique
Thu Aug 28 2014, 01:09 AM
hi,In the Tx code, I have disabled auto acknowledg...
ExperimenterUK Avatar
Posted By ExperimenterUK
Wed Aug 27 2014, 04:59 PM
Your board has two serial ports, are you connectin...
ExperimenterUK Avatar
Posted By ExperimenterUK
Wed Aug 27 2014, 04:45 PM
In your TX code I see where you set payload width ...
enisi Avatar
Posted By enisi
Wed Aug 27 2014, 07:05 AM
It can be more than one ansawer correctly
enisi Avatar
Posted By enisi
Wed Aug 27 2014, 06:57 AM
Port 0 is connected indicator 7 segments, so that ...
siddique Avatar
Posted By siddique
Wed Aug 27 2014, 01:48 AM
Pls check the Tx and Rx functions have made some c...
ExperimenterUK Avatar
Posted By ExperimenterUK
Tue Aug 26 2014, 06:03 PM
I assume you have made the changes I suggested to ...