THE DEVELOPMENT OF AN IMPROVED AUTOMATIC TELEPHONE MESSAGE ACQUISITION SYSTEM

Abstract

The automatic telephone message acquisition system is a device that works automatically with the position of the telephone handset. Whenever a telephone hand set is lifted (OFF HOOK.) the acquisition system is activated and it gives out a 6V as output voltage. Also when the telephone hand set is replaced, (ON HOOK.)The acquisition system is deactivated and it gives out a zero volt. as output voltage. The system is made of thee different modules; they are the switching circuit the alternating and filter circuit and the recorder circuit. When the telephone hand set is OFF- HOOK, the voltage that appears across the input terminals of the switching circuit is about 8 Volts, the voltage is far below the breakdown voltage of the ZDl (zener diode) that has a Vz of20V, therefore the transistor Qlis kept out of the circuit and the 9v battery takes over and produces a voltage output of about 6V or 3V depending on the selector switch position. Likewise, if the telephone handset is ON- HOOK, the voltage to the input of the switching circuit is about SOY, this input saturates transistor Ql and this keeps the switching circuit at off situation. With the switching circuit activated the audio circuit allows the recorder to record both sides of the telephone conversation. The filter circuit is made of a band pass filter that extracts out the needed information for recording by the tape recorder that makes up the recorder circuit.