FREE CIRCUIT DIAGRAMS 4U: Telephone line monitoring circuit

Free Electronic Circuits,Schematic Diagram,Circuit Diagrams

free, electronic circuit, circuit diagram, circuit schematic, schematic diagram, electronic diagram, audio, amplifier, power supply, guitar effect, current loop, current limiter, video, receiver, transmitter, transceiver, transistor, radio frequency, rf, active filters, digital, analog circuit, pwm, micro controller Free download

Free Electronic Circuits,Schematic Diagram,Circuit Diagrams

electronics circuit,circuits,schematic diagram,circuit design,circuit diagram, circuit

Electronic Circuit,Schematic Diagram,Circuit Diagrams

electronic circuit, circuit diagram, circuit schematic, schematic diagram, electronic diagram, audio, amplifier, power supply, guitar effect, current loop, current limiter, video, receiver, transmitter, transceiver, transistor, radio frequency, rf, active filters, digital, analog circuit, pwm, micro controller Free download

Best Song Lyrics Collection

Find The Music Lyrics To Any Song! It's Free DAILY UPDATED! One of the largest,most accurate, browsable and searchable song lyrics source on the net. lyric, lyrics, song, music, song lyrics, music lyrics

Monday, October 19, 2009

Telephone line monitoring circuit

This is very useful circuit for all because you can record telephone conversations automatically.What you have to do is connecting this unit to the phone line,Recorders remote control jack and to your tape recorder's microphone input.when the voltage of the line drops 5v or less it automatically starts to record.

Parts

R2 1.5K 1/4 W Resistor

R4 33K 1/4 W Resistor
C1 0.22uF 150 Volt Capacitor
R1 270K 1/4 W Resistor
Q1, Q2 2N4954 NPN Transistor
D1 1N645 Diode
R3 68K 1/4 W Resistor
MISC Wire, Plugs To Match Jacks On Recorder, Board, Phone Plug