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Transcript principle

2017-08-15 11:49  
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This article introduces the principle of recording conversations. In order to better grasp the principle of combining text, please understand this schematic. Figure: Point X and Y for circuit connection to the telephone line. As a voltage divider resistors R1 and R2. Voltage appears at R2 is the Fed's "microphone jack socket tape recorder. R1 and R2 values ??may change depending on the input impedance of the tape recorder's microphone jack terminals. Capacitor  C1 is used to block the flow of direct current Part II circuit control relays RL1, used to turn on / off the recorder. 48 volts appears in the on-hook state of the telephone line and this voltage drops to about 9 volts when the mobile phone. diodes D1 through D4 constitute a bridge rectifier / polarity guard. this will ensure correct polarity of the voltage transistor T1, regardless of the polarity of the telephone lines in the on-hook state, the output from the bridge (48 v DC) after 12 v regulator D5 and applied to the base of transistor T1 through a voltage divider including resistors R3 and R4. the switching of the transistors T1 and its collector is pulled low. turn, this causes the transistor T2 is not cut off and the relay RL1 energized when the phone is thrown off, the voltage point X and Y is less than 12 volts, so zenor diode D5 does not apply, therefore, the base potential of transistor T1 is pulled to ground through a resistor R4 and thus is cut off, so the base of transistor T2 to get forward biased through a resistor R5, the results energisation RL1 relay recorder is switched "and records begins. Recorder should remain fully loaded box and recorder should remain pressed the record button to record it once a mobile phone conversation. Capacitor C2 ensures the relay does not switch skelter times when a number is dialed in pulse dialing mode. The principle is very practical, you can Duokanjibian better grasp this principle again.

Conversation Recorder

Conversation Recorder

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