上海航天热工仪表厂生产的HW8501型无绳电话机对手机充电采用了限流式充电电路(见图1),充电电流是随着电池电压逐渐上升而减少。当电池电量充满时 ,充电电流维持在20毫安左右。此电话 The HW8501 cordless phone produced by Shanghai Aerospace Thermal Instrument Factory uses a current-limited charging circuit (see Fig. 1) to charge the mobile phone. The charging current decreases as the battery voltage gradually increases. When the battery is full, the charge current is maintained at about 20 mA. This phone