This simple circuit diagram lets you record your phone conversations automatically. The device connects to the phone line, your tape recorder’s microphone input, and the recorder’s remote control jack. It senses the voltage in the phone line and begins recording when the line drops to 5 volts or less.

parts :

R1—————————270K 1/4 W Resistor

R2—————————1.5K 1/4 W Resistor

R3—————————68K 1/4 W Resistor

R4—————————-33K 1/4 W Resistor

C1—————————-0.22uF 150 Volt Capacitor

Q1—————————-Q222N4954 NPN Transistor

D1—————————-1N645 Diode

MISC1———————–Wire, Plugs To Match Jacks On Recorder, Board, Phone Plug

source : www.aaroncake.net
phone-recorder