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Telephone Circuits,
Page 2
Telephone
Circuits: #-A
B-C D-F
G-N
O-S T-Z
Last Updated on:
Wednesday, June 02, 2021 05:07 AM |
| Circuits Designed by Dave
Johnson, P.E. : |
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Cut Phone Line Alarm
Burglars, rapists and other criminals will
often cut a phone line before they break into a home. The cut phone line will
prevent many alarm systems from alerting the police. The battery powered
circuit below will sound an alarm when the unit no longer detects the voltage
present on an active phone line....
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Links to electronic circuits, electronic schematics and designs for engineers, hobbyists, students & inventors:
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Basic FlashLamp Illumination Circuitry for Cellular Telephones/Cameras -
DN345 Design Notes (Linear Technology) (app note added 1/06)
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Build A HamComm Data Slicer - Until recently many of the ham radio
operating modes required specialist equipment that most often had to by
build and was exclusive to the task. Enter the Personal Computer. The PC
made life a little easier for the ham as it was now able to take over some
of the jobs that bespoke hardware did. But it still wasn't quite there yet.
The task of the PC was mainly to be a 'front end'(circuit / schematic added
6/07) |
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Build your own 89C51 PABX - This 89C51 PABX project is basically
an eight line intercom from which you can call one to eight numbers. The
89C51 PABX system also supports dialling and receiving telephone
calls….(circuit / schematic added 09/08) |
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Caller ID Circuits - information and circuits for different
systems used USA and Finland (added 5/02) |
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Caller ID Display Service - Caller ID decoder based on 68HC11, text in
French / (added 8/03) |
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Chip recorder customizes phone ringer - 25-Jul-02 Issue of EDN
Companies usually purchase one type of telephone for all employees, which is
understandable, especially if they obtain a discount for buying in quantity. One
ringer sound for everyone can pose a problem, though, if the sound of a ringing phone
makes a dozen people pause and look at their telephones. Equally annoying is the
absence of a visual message indicator.... [Design Idea by Don Schelle and Ted Salazar,
Maxim Integrated Products, Sunnyvale, CA] |
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Circuit translates A law to m law - 05/07/98 EDN-Design Ideas....Two common
methods exist to compand voice for transmission through a PCM channel. In Europe, A
law involves converting a 12-bit input signal to an 8-bit encoded output. In the US, m
law involves encoding 13 bits to 8 bits. You can use a translator to convert from A
law to m law....NOTE Page includes several designs, scroll to find this one....
[Design Idea by Rolando Herrero, Instituto Tecnol�gico de Buenos Aires,
ArgentinaRolando Herrero, Instituto Tecnol�gico de Buenos Aires, Argentina] |
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Circuit Vocalizes Telephone Number - 02/03/94 EDN-Design Ideas....The
circuit in Fig 1 is a simple method of vocalizing the digit number of a telephone
keypad, which, for someone visually impaired, provides helpful voice confirmation. A
75T202 dual-tone multifrequency (DTMF]receiver decodes the DTMF signal when you
depress the phone's keypad. The TC8801N voice synthesizer.... [Design Idea by Shwang-Shi
Bai, Chun-Shan Institute of Science and Technology, Lung-Tan, Taiwan] |
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Circuitry for Cellular Telephone/Camera Flash Illumination - AN95 Linear
TechnologyThis publication concerns implementation of high quality "Flash"
illumination in cellular telephones/cameras. Performance vs LED based illumination is
discussed and flashlamp operation reviewed. Considerations for support circuitry are
given, and a practical circuit, accompanied by performance data,....(appnote added
1/06) |
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Clip extracts signal from phone line - 24-Jul-03 Issue of EDN Using a
capacitive-coupled clip, you can pick up the signal from a twisted-pair or -wire
telephone line or from other unshielded analog lines without piercing the insulation.
No line test can detect the clip's presence, and it leaves no evidence of having been
attached. It needs no ground return. You can fasten the small, insulated pickup plates
to the opposing jaws of an alligator clip for qui.... [Design Idea by Maxwell Strange,
Fulton, MD] |
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Connecting a Picmicro® MicroController to a Standard Analog Telephone Line -
Microchip Application Note Published 21-Aug-02....[App Note] |
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Conversation Recorder - .... |
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Cordless Phone Backup #2 - .... |
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Creating your Own Telephone Ne2 Rk - you can easily create your own intercom
system using two telephones, a 9-volt battery (or some other simple power supply) and
a300-ohm resistor (added 5/02) |
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Cut Phone Line Alarm - Burglars, rapists and other criminals will often cut
a phone line before they break into a home. The cut phone line will prevent many
alarm systems from alerting the police. The battery powered circuit below will
sound an alarm when the unit no longer.... [Designed by David A. Johnson] |
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Cut Phone Line Detector - A while ago I got an email asking for the
schematic of a circuit to detect cut phone lines. It didn't take me long to find this
circuit in Electronics Now. When the circuit detects that a phone line has been cut,
it activates a MOSFET which can be used to drive a relay, motor, etc. It can also be
connected to a security system.... [Arron Cake] |
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Telephone Circuits, Page 2
Telephone
Circuits: #-A
B-C D-F
G-N
O-S T-Z |
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