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.

Get Social

Information

Powered by e107 Forum System

Conversation

Sat Aug 01 2015, 05:57 AM
ghulamqadir
i want to communitcate wifi module with android phone using pic18f4550. Any Suggestion????????
Sat Aug 01 2015, 05:56 AM
ghulamqadir
Slam
ExperimenterUK
Thu Jul 30 2015, 11:41 PM
@Muhammad Aarshad build what ?
Wed Jul 29 2015, 06:42 PM
Muhammad Aarshad
Hello I want to build it, but I don't know how can I program the micro controller. Can You send me the code of the IC? Thanks in advance My e-mail: [email protected]
Sat Jul 25 2015, 10:37 PM
Arnali
What does the cross means? The ones from pin 7,8,9,10 of the LCD?
Fri Jul 24 2015, 09:53 AM
HARSHAL PATIL
....
shyam
Thu Jul 23 2015, 01:42 PM
hi Ajay
ajay_bhargav
Mon Jul 20 2015, 04:38 AM
@Rohit Biradar, I am glad my tutorial helped
Thu Jul 16 2015, 06:19 PM
Rohit Biradar
Thanks a lot publisher of this tutorial. Everybody tells about the nibble sending methods and the command set for 4-wire lcd interface. You are the first to tell me about the most important part that is resetting the lcd. This thing got me all day. Now I can sleep in peace. Thanks once again. Million thanks.
Thu Jul 16 2015, 12:24 PM
Baby
my project is related to control the door in dam. by keil program how can i control the same.

Downloads

Comments

albatain
Fri Jul 31 2015, 02:58 AM
KDN
Wed Jul 29 2015, 05:14 AM
Tanvir.
Fri Jul 24 2015, 07:59 AM
erummumtaz
Thu Jul 23 2015, 10:47 PM
balvant
Thu Jul 16 2015, 03:56 PM
seoulmak
Mon Jul 13 2015, 01:21 PM
SHIVKHUMAR
Sat Jul 11 2015, 04:10 AM
Nals99
Fri Jul 03 2015, 08:33 AM

Online

Guests: 32, Members: 0 ...

most ever online: 182184
(Members: , Guests: 182184) on 06 Aug 2010: 05:37 AM

Members: 37679
Newest member: albatain
Forum Activity
Mc_Comet32 Avatar
Posted By Mc_Comet32
Sun Jul 26 2015, 05:49 PM
ExperimenterUK Avatar
Posted By ExperimenterUK
Thu Jul 23 2015, 08:14 PM
Try this link.Basically find the tacho output pin...
seoulmak Avatar
Posted By seoulmak
Mon Jul 20 2015, 03:44 PM
ajay_bhargav Avatar
Posted By ajay_bhargav
Mon Jul 20 2015, 04:42 AM
Ok then, check if you did not mention "LCD_ClearSc...
ajay_bhargav Avatar
Posted By ajay_bhargav
Mon Jul 20 2015, 04:41 AM
I am assuming you're talking about the small CPU f...
ajay_bhargav Avatar
Posted By ajay_bhargav
Mon Jul 20 2015, 04:36 AM
Amit Kumar Das Avatar
Posted By Amit Kumar Das
Sun Jul 19 2015, 04:17 AM
Yes they are fine. I have included everything. Una...
seoulmak Avatar
Posted By seoulmak
Fri Jul 17 2015, 08:41 AM
yes, but i need more information to connect the f...
balvant Avatar
Posted By balvant
Thu Jul 16 2015, 04:07 PM
ExperimenterUK Avatar
Posted By ExperimenterUK
Wed Jul 15 2015, 05:42 PM
Is this a project listed on this site ?