What are the uses of multimeters at home?
For an electrician, a multimeter can determine almost 80% of faults. But for families, if you have a multimeter, when a household circuit fault occurs, you can basically measure the voltage, continuity, and ground resistance, and you can basically solve the household circuit fault.
If you have a multimeter at home, you almost don't have to worry about problems with the home circuit. After all, the home circuit is simple, so at least you don't have to worry about accidentally touching a live object. But if you don't have a multimeter at home, it's actually okay. Because the home circuit is simple, problems are basically minimal.
Multimeters are still very useful in family life.
Measure battery
Evaluating whether the battery at home is still charged is a problem that everyone often encounters. Especially some appliances that use more than two batteries, such as remote controls, doorbells, electronic blood pressure monitors, etc. Often one of the batteries is out of power, causing the entire battery pack to have no output. If a meter is not used, the entire battery pack may be thrown away. It creates a lot of waste. Here's how to measure the battery with a multimeter:
①Measure voltage
First, set the multimeter to the DC voltage range, and the range selection should be slightly larger than the voltage being measured. For example, when measuring a 1.5v battery, follow the following method:
For the digital meter on the left, select 2V with white numbers, and for the pointer meter on the right, select DCV 2.5v. Then insert the black test lead into the C0M hole and the red test lead into the "VΩ" hole. When testing the battery, the digital meter can read directly. The pointer meter should look at the scale line with the full scale value of 250 (2.5, 25, and 250 all use this scale)
The measurement result pointer deflects to the 150 position, which means that the voltage of the battery under test is 1.5V. For batteries measuring other voltages, just follow the same method and adjust to the corresponding gear.
②Measure current
When measuring battery current, you must first adjust the test lead jack. Black plugs into C0M, red plugs into 5A or 10A holes.
Strictly speaking, it is not allowed to use an ammeter to directly test the battery. However, for small-capacity dry batteries, testing them within a limited range for a short period of time is a shortcut to selecting batteries.
This is because some batteries are fine when tested with voltage settings, but when installed on electrical appliances they will show insufficient power. This is what we usually call "floating electricity" or "virtual electricity". From a professional point of view, it is the internal resistance of the battery that is causing trouble. For such a battery, it will be "revealed" when measured with an ammeter. For example, when measuring dry batteries from size 1 to size 7, you can directly use the 5A or 10A DC current range to measure, but the measurement time should not exceed 1 second. Generally speaking, the new AA battery will not be less than 1 amp, while the AA battery will reach more than 5 amps. We can use this method to screen and pair batteries to truly make the best use of them. However, the current of mobile phone lithium batteries cannot be directly measured because there will be no current output due to the protection circuit.
Measuring household appliances
For household appliances such as electric kettles, electric heaters and hair dryers, you need to use the Ω range of a multimeter to judge their quality.
First, set the multimeter to the Ω position. The digital table is 2K and the pointer table is Rx10. For the dial scale, you can look at the one marked with "Ω" at the top, and just read the pointer x10. Plug the black test lead into C0M and the red lead into "+" or "VΩ".
①Electric heating appliances
For electric heaters, electric kettles, hair dryers, etc., when the power is off, turn on the power switch and measure the resistance of the plug. Generally, it is between tens of Ω, which can be considered good.
②Motor type
Household motors generally include range hoods, exhaust fans, electric fans, refrigerators, and small electric drills. The measurement method is also to turn on the power switch when the power is off and measure the resistance of the two pins of the plug. Generally, a few hundred Ω is normal.
The above two resistance value ranges are reference values. The greater the power, the smaller the resistance value. But it does not include rice cookers with electronic speed regulation and various automatic functions, because its control circuit needs to be powered on to work, and the resistance cannot be measured when the power is off.
③Various types of power adapters
To measure power supply, you need to set the multimeter to the DC voltage setting, and the resistance setting cannot be used. Its gear selection principle is also slightly larger than the voltage being measured. Use the test lead to directly measure the plug output of the electrical adapter, or insert the test lead into the USB socket for measurement:
