How to measure wire continuity with a digital multimeter
1. A digital multimeter is a sharp tool for electronic measurement, which can be used to measure the continuity of circuits in daily life. Multimeters are divided into digital multimeter and pointer multimeter. It is generally divided into voltage range (AC+DC), current range (AC+DC), and resistance range. Measuring on/off requires the use of a resistance range, which is the simplest function.
2. Let's take a dental probe as an example. The probe is a plastic handle connected to two metal needles, similar to our usual leather wire. To determine whether points A and B are conductive, we use the following steps:
1) Firstly, ensure that the wiring is correct. Insert the black wire into the COM socket and the red wire into the V (omiga, or secondary tube interface)
2) Position it at 200 of the resistance range, or at the "buzzer, diode" range.
3) Connect the red or black pens to both ends of A and B to be measured. If A and B are disconnected, the LCD screen will display "1", indicating infinite resistance.
4) Using the same method, measure points A and C to determine if they are connected. If the wire is connected, there will be a beep prompt sound, and the LCD screen will display a number close to "0", in this example, it will display "0.001"; When using a resistance range, if the wire is connected, a jumping number less than 200 will be displayed. The accuracy of a multimeter varies, and this measurement number also varies, but when conducting, it will always be a number close to zero.
The above methods can be applied in daily life, such as measuring the on/off of wires and electrical switches.
3. In daily life, there are other devices that can also be measured using this method, such as headphones, speakers, etc., but their resistance is slightly higher. The following figure is a schematic diagram of a headphone, which can be seen as having two channels, one on the left and the other on the right. Essentially, the common end and the left and right channels are connected to a coil, which vibrates and produces sound when powered on. The resistance of the coil is generally 30-100 ohms.
4. During actual measurement, the red and black probes can be connected to the common terminal and the left and right channel terminals respectively. Be careful not to touch the wires between the red and black probes. The following example shows 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 determine another channel.
5. For a pointer multimeter:
1) Correctly connect the red and black pens
2) Connect the red and black pen to both ends of the measuring line
3) If the pointer resistance is close to zero or relatively small, it indicates that the line is connected. If it does not move or the resistance is high, it indicates that the wire is disconnected.
