DC power supply under-voltage, over-voltage indicator circuit shown in Figure 13-93, use it to monitor the DC power supply voltage is normal. When the supply voltage is 12V, ad
just RP, the sampling voltage of 6V. Two light-emitting diodes are not bright. When the power supply down to 11. 9V, the green LED lights VLz; when the supply voltage exceeds 12.1V, the red LED lights VLi.