Telephony Circuits, DTMF Circuits

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Telephone circuits

related topic: Telephony

2 line phone status indicator pdf file

9-line telephone sharer This circuit is able to handle nine independent telephones (using a single telephone line pair) located at nine different locations, pdf file

Build your own inductive telephone tap an inductive telephone tap that will allow us to listen to telephone conversations nearly undetectably

Cordless phone frequencies cordless phones are still analogue and use the frequency from 30-50MHz. The signal is FM-modulated and can easy be picked up with any FM-receiver

Cut Phone Line Detector schematic of a circuit to detect cut phone lines

DTMF Coding and Decoding Module Two chips are adopted for DTMF coding and decoding respectively

DTMF decoder circuit

DTMF Phone Dialer

DTMF Generation with a 3.58 MHz Crystal DTMF generation consists of selecting and combining two audio tone frequencies associated with the rows (low band frequency) and columns (high band frequency) of a pushbutton touch tone telephone keypad, pdf file

DTMF generator/decoder Dual-tone-multi-frequency (DTMF, also known as touch-tone) are the audible sounds you hear when you press keys on your phone

DTMF tone decoder with LCD display this project displays telephone numbers decoded from tones. A microphone picks up the tones, a preamplifier boosts the signals, an SSI-202 DTMF chip decodes the tones, a Basic Stamp acts as an interface to an LCD display and also provides "RS-232" serial output

DTMF - Decoding with a 1-bit A/D converter The purpose of DTMF decoding is to detect sinusoidal signals in the presence of noise

Caller ID display service en Français

Démodulateur DTMF CD22202, en Français

Device control using Telephone using home phone as a local phone and another phone - either landline or mobile phone as a remote phone

FM Telephone Bug a simple transmitter that when connected to a phone line, will transmit anything on that line (execpt the dial tone) to any FM radio. The frequency can be tuned from 88 to about 94Mhz and the range is about 200 feet

Generating DTMF tones using computer soundcard

Phone amplifier telephone amplifier circuit

Phone in use indicator

PLL tone decoder IC The BA1604 and BA1604F are tone decoder ICs that enable the frequency to be selected in precise detail, using a PLL
system. These ICs are configured of a PLL circuit, a detection circuit, a voltage comparator circuit and an output logic drive circuit, pdf file

Remote control using telephone a teleremote circuit which enables switching ‘on’ and ‘off’ of appliances through telephone lines

Remote Telephone Ringer This remote telephone bell ringer allows you to use a large (and loud) external bell in place or in addition to the built in (and rather wussy) ringer in most modern telephones

Smart ringing phone light to switch on a lamp when the tele- phone rings

Telephone conversation recorder enables automatic switching-on of the tape recorder when the handset is lifted

Telephone in use indicator

Telephone line audio interface circuits How telephone works, Network Interface in telephone, Telecom hybrid circuits for other equipments than telephones, Audio interfaces to telephone lines, Telephone audio interfaces from Usenet news, Audio interfaces without transformer isolation, Simple telecom hybrid circuits, More details implementing telephone line interface, Problems in linking telephone hybrid to audio system, Helpful tips for telephone hybrid circuit designers, Connecting hybrids and telephone equipments, Components for telephone line interfacing, Telephone line technical details, Telephone line details in different countries, Interference in the telephone line signal

Telephone line simulator construction project telephone line simulator with dialtone, busy tone & ring signal

Telephone line status indicator pdf file

Telephone Number Display The given circuit, when connected in parallel to a telephone, displays the number dialled from the telephone set using the DTMF mode. This circuit can also show the number dialled from the phone of the called party, pdf file

Telephone record control this circuit will allow you to connect any tape recorder that has a mic and remote input to a phone line and automatically record both sides of a conversation when ever the phone is in use

Telephone recorder this circuit automatically records all incoming and outgoing phone conversations with an ordinary cassette or tape recorder

Telephone Ring Generator Using Switching Supply

Telephone ringer using 556 dual timers using modulated rectangular waves of different time periods, The circuit presented here produces ringing tones similar to those produced by a telephone

Two line intercom plus a telephone changeover switch The circuit presented here can be used for connecting two telephones in parallel and also as a 2-line intercom

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