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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pravin_35 Avatar
Posted By pravin_35
Mon Jul 28 2014, 01:33 PM
I suggest you to try with another chip of same and...
pravin_35 Avatar
Posted By pravin_35
Mon Jul 28 2014, 05:29 AM
I suggest you to try with another chip of same and...
ajay_bhargav Avatar
Posted By ajay_bhargav
Mon Jul 28 2014, 03:23 AM
I suggest you to try with another chip of same and...
pravin_35 Avatar
Posted By pravin_35
Mon Jul 28 2014, 03:11 AM
just now tried with Mplabx screen shotpravin_35Are...
ajay_bhargav Avatar
Posted By ajay_bhargav
Mon Jul 28 2014, 02:45 AM
just now tried with Mplabx screen shotpravin_35Are...
pravin_35 Avatar
Posted By pravin_35
Mon Jul 28 2014, 01:06 AM
If you uncheck program memory and EEPROM it means ...
ajay_bhargav Avatar
Posted By ajay_bhargav
Mon Jul 28 2014, 12:34 AM
If you uncheck program memory and EEPROM it means ...
ajay_bhargav Avatar
Posted By ajay_bhargav
Mon Jul 28 2014, 12:32 AM
HC-06 module is nothing but a serial connection ov...
pravin_35 Avatar
Posted By pravin_35
Mon Jul 28 2014, 12:30 AM
Try to change the DS1307 chip. It might have gone ...
ajay_bhargav Avatar
Posted By ajay_bhargav
Mon Jul 28 2014, 12:28 AM
@PavanKh, Please post in a new thread.

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ajay_bhargav
Mon Jul 28 2014, 12:34 AM
@ Anshu Raj sorry we do not take such requests.
Sun Jul 27 2014, 12:23 AM
Anshu Raj
sir plz send the automatic collage alram bells in 2 hrs bells ring. For microcontroller programme plz sir
ajay_bhargav
Thu Jul 24 2014, 01:06 AM
@R.ABHISHEK where? I dont see it. is it in forum?
Wed Jul 23 2014, 05:49 AM
R.ABHISHEK
sir,pls message on microcontroller 8051 assambly language new program
Wed Jul 23 2014, 05:47 AM
R.ABHISHEK
sir,pls message on 8051 microcontroller assambly language program new quastions
ajay_bhargav
Tue Jul 22 2014, 09:18 AM
@Pragya Android application is taken from google play. Only Author has its source with him. Application is only used in this project.
Tue Jul 22 2014, 04:58 AM
Pragya
plz send me 8051 code and android code for android based device controller via Bluetooth .Here in this project I am using Hc-06 Bluetooth module
Thu Jul 10 2014, 09:57 AM
Caleb
plz someone mail me the source code for that project
Thu Jul 10 2014, 09:57 AM
Caleb
http://www.8051projects.net/download-d188-control-your-pc-tv-remote.html
ExperimenterUK
Tue Jul 08 2014, 03:25 PM
Post questions in the forum.. this area is for chat

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Mon Jul 28 2014, 03:15 AM
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