Four wonderful ways to use a digital multimeter
1. Determine whether the circuit or component is electrified
The AC voltage range of numbers is very sensitive, even if there is a small induced voltage around it, it can be displayed. Based on this characteristic, it can be used as a testing pen. The usage is as follows: Set the multimeter to AC20V mode, hang the black probe in the air, hold the red probe and make contact with the side line or device. At this time, the multimeter will display. If the displayed number is between a few volts and a dozen volts (different multimeters will have different displays), it indicates that the line or device is charged. If the display is zero or very small, it indicates that the line or device is not charged.
2. Distinguish whether the power supply line is a live wire or a neutral wire
The first method:
The above method can be used to determine: the one with a larger display number is the live wire, and the one with a smaller display number is the neutral wire. This method requires contact with the measured circuit or device.
The second method:
No need to make contact with the measured circuit or device. Set the multimeter to AC2V mode, hang the black probe in the air, hold the red probe and gently slide the tip along the line. If the voltage displayed on the meter is a few volts, it indicates that the line is a live wire. If it is only a few tenths of volts or even smaller, it indicates that the line is a neutral wire. This method of judgment does not directly contact the circuit. It is not only safe but also convenient and fast.
3. Find the breakpoint of the cable
When there is a break in the cable, the traditional method is to use a multimeter resistor to block and search for the break section by section. This not only wastes time, but also greatly damages the insulation of the cable. The sensing characteristics of a digital multimeter can quickly locate the disconnection point of a cable. First, use a resistance switch to determine which cable core wire has broken. Then connect one end of the broken core wire to AC220V. Then, set the multimeter to the AC2V position, with the black probe hanging in the air. Hold the red probe and gently slide it along the line. If the voltage displayed on the meter is a few volts or a few tenths of a volt (depending on the cable), and if it suddenly drops significantly when moved to a certain position, record this position: usually. The breakpoint is located between 10-20cm in front of this position.
