Digital multimeter to measure the continuity of wires
1. A digital multimeter is a powerful tool for electronic measurement. It can be used to measure the on-off of lines in daily life. Multimeters are divided into digital multimeters and pointer multimeters. Generally divided into voltage file (AC + DC), current file (AC + DC), resistance file. It is the simplest function to use the resistance gear to measure the continuity.
2. We take a dental probe as an example to illustrate. The probe is a plastic handle connected with two metal needles, which is similar to our usual leather wire. In order to determine whether points A and B are connected, we use The following steps:
1) First 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 is placed at 200 of the resistance gear, or the gear of "buzzer, diode".
3) Connect the red pen or black pen to the A and B ends to be measured respectively. 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 buzzer sound, and the LCD will display a number close to "0", in this case, "0.001"; when using the resistance gear, if the wire is connected, it will display Beating numbers 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.
The above method can be used in daily life, such as measuring the on-off of wires, on-off of electrical switches, etc.
3. In daily life, there are other devices that can also be measured by this method, such as headphones, speakers, etc., but their resistance will be slightly larger. The figure below is a schematic diagram of an earphone. It can be seen that there are two left and right channels. The essence is that the common end and the left and right channel ends are respectively connected with a coil, which vibrates and sounds when powered on. The resistance of the coil is typically 30-100 ohms.
Digital multimeter to measure the continuity of wires
4. During the actual measurement, you can connect the red and black test pens to the common end and the left and right channel ends respectively. Be careful not to touch the lines between the red and black test pens. As you can see in the example below, the resistance between the left channel and the common terminal is measured to be 33 ohms, indicating that this channel is normal. The other channel can also be judged in the same way.
5. For the pointer multimeter:
1) Correctly connect the red test lead and the black test lead
2) The red and black test leads are connected to both ends of the line to be measured
3) If the pointer resistance is close to zero, or relatively small, the line is connected. If it doesn't move, or the resistance is high, the wire is broken.
