Telephone and intercom related schematics

Posted by Author makecircuits

1-line telephone status indicator (PDF)
300 baud modem circuit schematic
4-line telephone status indicator (PDF)
8-line intercom system using 89C51 microcontroller
Assorted telephone circuits
Caller ID decoder
Caller ID decoder part 1
Caller ID decoder part 2
Cellular Phone calling Detector
Cut Phone Line Detector
Cut phone line detector
Cut telephone line detector
Detecting a telephone RING
Digisound ring modulator
Digital/Standard Phone Line Tester
DTMF decoder / logger
FM Telephone Bug
FM telephone line bug transmitter
Greek telecard reader
Hold function for Telephone
Home made PBX / PABX
Incoming call indicator
Infinity Transmitter Schematic and Plans
Line in use indicator (PDF)
NCDS Interface Schematic for Nokia 3110, 8110, 8110i
Phone Busy Indicator
Phone in-use
Phone In-Use Light
Phone line in use indicator
Phone Line to Audio
Phone Off-Hook Indicator
`phone rang` indicator light
Phone ring circuit schematic
Phone to audio interface
Phone-In-Use indicator
Ringing Phone Light Flasher
Simple circuit to connect telephone equipment to audio mixer
Simple Phone Tap
Simple telephone line tap for intercepting telephone calls
Soft musical telephone ringer
Talking phone dial monitor
Taxi phone automatic dialler
Telephone amplifier
Telephone Audio Interface
Telephone autodialler
Telephone Hold Button
Telephone in use light
Telephone interfacing / caller ID using a PIC microcontroller
Telephone In-Use LED Indicator
Telephone In-Use Relay Circuit
Telephone Line Monitor
Telephone line monitor
Telephone line simulator
Telephone music on hold box
Telephone music on hold interface
Telephone privacy adapter
Telephone Recorder
Telephone recording circuit
Telephone ring controlled relay
Telephone Ring Generator Using 60Hz Power Transformer
Telephone Ring Generator Using Switching Power Supply
Telephone ringing circuits
The Link 4+0 - Internal Intercom
The Link A2B+1 (the Link Telephone Intercom - DTMF version)
The Original 2 Phone Intercom Link Design
Universal telephone hold
Use old phones as an intercom