Digital multimeter to measure the continuity of electric wires
1. The digital multimeter is a sharp tool for electronic measurement, which can be used to measure the continuity of the circuit in daily life. Multimeters are divided into digital multimeters and pointer multimeters. Generally divided into voltage files (AC + DC), current files (AC + DC), resistance files. The resistance file is used to measure continuity, which is the simplest function.
2. Let's take a dental probe as an example. The probe is a plastic handle connected with two metal needles, which is similar to our usual leather wire. In order to judge whether point A and point B are connected, we use The following steps:
1) First of all, make sure that the wiring is correct, the black wire is inserted into the COM socket, and the red wire is inserted into the V (omiga, or diode interface)
2) The gear position is placed at 200 of the resistance gear, or the gear of "buzzer, diode".
3) The red or black pens are respectively connected to the ends of A and B to be measured. If A and B are disconnected, the LCD will display "1", which means the resistance is infinite.
4) Use the same method to measure points A and C to determine whether they are connected. If the wire is connected, there will be a beep sound, and the LCD screen will display a number close to "0", in this example, "0.001" is displayed; when using the resistance file, if the wire is connected, it will display Number of beats less than 200. The accuracy of the multimeter is different, and the measurement number is also different, but when it is turned on, it will be a number close to zero.
With the above method, it can be applied in daily life, such as measuring the on-off of wires, the on-off of electrical switches, etc.
3. In daily life, there are other devices that can also be measured by this method, such as earphones, speakers, etc., but their resistance will be slightly larger. The picture below is a schematic diagram of a headphone. It can be seen that there are two left and right sound channels. The essence is that a coil is connected to the common end and the left and right sound channel ends respectively. When the power is turned on, it vibrates and sounds. The resistance of the coil is generally 30-100 ohms.
Digital multimeter to measure the continuity of electric wires
4. During the actual measurement, you can connect the red and black test leads to the common terminal and the left and right audio channel terminals respectively, and pay attention not to touch the lines between the red and black test leads. In the example below, it can be seen that the measured resistance between the left channel and the common terminal is 33 ohms, indicating that this channel is normal. You can also use the same method to judge another channel.
5. For pointer multimeters:
1) Correctly connect the red and black test leads
2) Connect the red and black test leads to both ends of the line to be measured
3) If the pointer resistance is close to zero, or relatively small, it means that the line is connected. If it doesn't move, or if there's a lot of resistance, the wire is disconnected.
