| 摘要 |
PURPOSE:To select the listening by means of either a simple on a complicated signal, by encoding a plurality of remote control signals according to the preset state of a switch group and enabling the listening of recorded message to be remote-controlled only with the first common signal. CONSTITUTION:A remote control listening system for a device which responds from a tape T-1 in response to a callout signal and records an input signal on a T-2, is divided into two parts and a common signal L is given to them at first. In the wiretapping preventing system where a switch SW5 is selected to the position B, remote control signals L, R (frequencies f-1 and f-2) are coded according to the preset state of switches SW1-SW4 and transmitted to perform remote control listening. In the simple system where the SW5 is selected to the position A, only the common signal L is used, and a remote control circuit 10 is driven with an output of a Schmitt circuit 8 of H level with a relay Y-1, a transformer LT and a filter 4 for the signal L, via the switch 5, an OR gate 10 and a relay Y-2 to listen to the tape T-2. |
