| 摘要 |
The TV set acting as an interphone using the common antenna cable includes a resistor (R1) and a condensor (C1) for regulating the bell signal of the interphone, a diode (D1) for setting the bell signal to a certain level and for setting the bell signal to a certain level and applying voltage of positive logic level to the bell detecting terminal of the microprocessor, a switch (150) for seclecting the interphone function when turned on and making the microprocessor control the switches (120)(140) to return to the TV function when turned off, and the interphone-key (130) for setting the address of the TV set which the user wants to call.
|
