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ADSL line filter – Circuit Schematic
ADSL line filter
The above diagram is a standard low-pass telephone line filter (L1,C1,L3,C2). L2 and L4 are needed since we're dealing with the 'Tip' and 'Ring' of a phone line...
Telephone Hold Line – Circuit Schematic
Telephone Hold Line
The UNIVERSAL HOLD circuit detects the dual tone, multi frequency (DTMF) tone that is generated when the # key is pressed and then activates a circuit that par...
DTMF decoder with voice! – Circuit Schematic
DTMF decoder with voice!
The Talking Phone Dial Monitor detects the tones generated when numbers are dialed on your touch tone telephone and speaks the numbers that were dialed. This...
Telephone Line Controller – Circuit Schematic
Telephone Line Controller
A very simple circuit, that will find application in the case where you have a lot of telephones installed on a telephone line and would want to know if somebo...
Telephone Line optical and sound Ring – Circuit Schematic
Telephone Line optical and sound Ring
It is a relatively simple circuit, with which we can have optical and sound clue, when we have telephone ring in the line of telephone. The calls in the line, a...
Phone Line In use LED – Circuit Schematic
Phone Line In use LED
If we have a lot of parallel telephones on a telephone line, we needed a unit that will have the possibility of showing if somebody of the telephone has raised ...
Dual phone line auto recorder – Circuit Schematic
Dual phone line auto recorder
Many times exists the need recording some conversations from a telephone line and this it's relatively easy. If we want however to have the possibility recordin...
Scope Probe – Circuit Schematic
Scope Probe
Working on live telephone circuits can be a problem. You just can't connect a normal scope probe to the circuit while it is tied to the phone line. Neather sid...
Phone Line Simulator with PIC16F819 – Circuit Schematic
Phone Line Simulator with PIC16F819
Creating projects that connect to the phone line can be a real chore without some device like this. It generates the 48 volts DC for the on-hook condition, the ...
Phone digital answering machine – Circuit Schematic
Phone digital answering machine
This unit is an upgrade of the previous phone call interceptor. Instead of using an answering machine to provide the outgoing message and recording functions, i...
Phone in Hold with Music – Circuit Schematic
Phone in Hold with Music
This circuit will allow you to place a phone call on hold and if you wish to have them listen to music while they are on hold. The circuit operates as follows: ...
Phone Line In use LED with 2N2222 – Circuit Schematic
Phone Line In use LED with 2N2222
With this circuit mounted in or near every phone in the house, it will allow users to know if the phone is being used and not to pick up the phone. When a phone...
Auto Telephone line Recorder – Circuit Schematic
Auto Telephone line Recorder
his 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 wh...
Phone Bill Calculator – Circuit Schematic
Phone Bill Calculator
This circuit is used to give "1" signal when the phone is ringing. As you can see the ct. is directly connected to the phone line. The 4.7 uF blocks the DC loa...
Radio Glen Transmit Selector system – Circuit Schematic
Radio Glen Transmit Selector system
The main box of the Transmit Selector system is designed to be located in the technical rack of a small radio broadcast station. There are four stereo balanced ...
Radio Glen TBU – Circuit Schematic
Radio Glen TBU
The heart(s) of the unit are the ETAL P3400 line modules available from Farnell. These modules mop-up all of the line interface functions like ring detection, p...
Cellular Phone Jammer with 555 – Circuit Schematic
Cellular Phone Jammer with 555
And my recent study about chaos is really making me have FUN! The subject is awesome! And my Geeky Bro informed me something about a cell phone jammer, a simpl...
Phone Call answering machine (PIC16F870) – Circuit Schematic
Phone Call answering machine (PIC16F870)
The PIC16F870 chosen for this project has seval analog channels. One of these is used to capture the DTMF tones and decode the digits. The actual phone conne...
Line Powered Phone Messager (PIC16C819) – Circuit Schematic
Line Powered Phone Messager (PIC16C819)
The phone company provides 3 levels of power. With no devices 'off hook' the line rests at 48 volts DC. If you draw any more than a fraction of a milliamp or s...
ADSL Splitter Adapter – Circuit Schematic
ADSL Splitter Adapter
This really isn't much an electronics project as it is a telephone wiring project. Take note that this proejct involves connections to telephone lines. This may...