GB1388037A - Automatic telephone answering machine - Google Patents

Abstract

1388037 Substation equipment ; transistor amplifier oscillator and delay circuits W MULLER 24 April 1972 [3 Dec 1971] 18855/72 Headings H4K and H3T A telephone answering machine has a first recording unit for providing an answering announcement and a second recording unit for recording a caller's message where the second unit is switched on by circuitry which responds to a control signal (tone) replayed by the first unit after the answering announcement and a second control signal is replayed by the first unit after a closing announcement to cause the machine to reset itself. The schematic diagram shown provides an announcement arrangement 33 and a message recording arrangement 31 which can be connected to line La, Lb through changeover relay 37. The tone required to switch over relay 37 is provided by the amplifier/ oscillator circuit 20 which includes a bridged-T filter circuit 23. Whilst the announcement is being recorded, operation of button 26 causes transistor 25 to conduct to short-circuit resistor 24 and cause the circuit 20 to oscillate. A burst of tone is provided after the answering message and a further longer burst of tone is provided after the closing announcement. When the telephone line is rung circuit 8 causes the line to be looped and answering arrangement 33 to be switched on and the answering announcement read by head 14 transmitted through amplifier 11 to the line. The shorter recorded tone passes through circuit 20 to circuit 30 before contact 29 changes over and causes recording arrangement 31 to operate. The caller's message passes from the telephone line to head 13 and the speech signals also pass through speech switch 34 and timer 35 to maintain arrangement 31 in operation. At the end of the overall time or when silence is received the relay 36 drops contacts 37 to operate arrangement 33 and play the closing announcement. The long burst of tone provided at the end of the announcement causes the rewind/reset arrangement 32 to be operated through contact 29. A switching circuit, Fig. 3 (not shown), is used to provide delayed switching of contact 29 so that the first incoming pulse has decayed sufficiently not to operate circuit 32 when contact 29 is changed over.