| 摘要 |
PURPOSE:To automatically stop the radiation of electromagnetic waves from the radio unit for the long time pressing, by judgement whether the press operation with the press-to-talk switch is a transient long time pressing required or other long time pressing. CONSTITUTION:The capacitor C of the detection circuit 1 is charged to the power supply voltage at all times. If the press-to-talk switch SW is closed in a short time, the discharge voltage of the capacitor C is not decreased to the start voltage of the first timer circuit 3. Accordingly, the transistor TR is ON. When the switch SW is long closed, the terminal voltage across the capacitor C is lowered to the voltage starting the timer circuit 3. After the start of the timer circuit 3, FF circuit 6 is set after the delay time of the delay circuit 4 and the transistor TR is not turned on. |
