Some decades back most probably only electronic technicians or engineers used multimeter. But nowadays Digital Multimeter is a very handy testing device and it’s supposed to be in the tool box of any person.
The multimeter is wonderful tool for testing the operational status of any electronic device or wiring connection. There are two kinds of multimeter available in the market the, one is analog while the other is digital.
In digital multimeter, the exact value is displayed in numbers while in analog multimeter a needle point out the value over a range. Sometimes you might wonder why the light didn’t glow when you switched it on.
There might be some reason; the light bulb may be fused or the lamp cord may be shorted or the lamp itself may be damaged. This is one such example where multimeter can be used to determine the cause of a malfunctioning device.
Out of many useful functions of multimeter, resistance, or continuity test is a good parameter of determining a device condition. As a safety precaution to avoid any eclectic shock it’s advised to never ever use continuity test function on a device that is powered on at the very moment.
It should be checked that the device is not plugged in to any power source and if so unplug it. Once unplugged, you should set the multimeter to resistance (Ohms) mode. To check the readiness of multimeter, you should touch the two test probes together (the red one set for “positive” and the black one for “negative”).
The multimeter should display zero indicating that your multimeter is ready to test devices. A zero resistance means that the device’s circuits have continuity and the device has a closed circuit capable of conducting current. So for your first simple test, get your light bulb by removing it from lamp socket.
Now connect one probe to the bottom of the bulb by touching it while connect other probe to the threaded side of the bulb. If the multimeter displays a zero resistance, the bulb passes continuity test and it is in good working condition.
If it doesn’t indicate zero that is continuity, then the circuit is broken down and current can’t flow through may be due to a broken filament. With the same method of simply connecting the two ends of electrical cord, its condition can also be checked.
If the test doesn’t show continuity, then the circuit is broken and certainly the cord is damaged. It should always be remembered not to test continuity on any cord or device which is powered on. As a basic rule always disconnect any power or current source before performing test.
To test switch, connect the probe pin on each side (pole) of the switch. Now turn the switch position to power on and you will notice that multimeter reading changes from zero to infinity. If it doesn’t show infinity, them the switch is damaged.
Similar test can be performed on a Photovoltaic solar cell to test its condition. By touching the probe on each of the tabs on the cell, the continuity and thus working condition of the cell can be tested. If multimeter shows zero resistance, then there may a problem and you’ll need to start trouble shooting.
So after going through the manual and instructions of digital multimeter, you can perform more complex and detailed electrical tests. A multimeter can also measure the ampere and voltage of any alternating current (AC that is household current) or direct current (DC or battery current) in a live circuit.
Normally a multimeter can test 120 volts AC current in a home circuit. Multimeter can also be used to check the strength of DC batteries. With the time you will learn how to properly use a basic multimeter and someday you will definitely feel delighted to be able to determine the reason of malfunctioning of your day to day appliances.