One of the main tools of an electronic technician is a "Multi Meter" tool which can either be "Digital" or "Analog" device. The digital version is more commonly referred as the "DMM" (stands for Digital Multi Meter) while the analog version is known as the "VOM" (stands for Voltage Ohm Meter). Despite the difference, both of these device have the same purpose which is to measure different properties of electricity such as voltage, current and resistance.
Multi Meter tool either analog or digital needs to be adjusted by pressing the buttons or rotating the knobs into the type of unit that you would like to read. In order to make an actual reading of a certain component, you have to use the two wired pointers which is a red and black color probes (more commonly known as "test probes"). The red colored pointer actually indicates positive polarity while the black colored pointer is the negative polarity or ground.
Let's say for example that you are going to read the voltage rating of a certain battery. Before you do, you have to make sure that you set the tool into the its proper "voltage" setting.
Next step is to hold the wired pointers with your hands. One pointer on each of your hand. If you are a right-handed person then it's best to always handle the red or positive pointer on your right while your left hand holds the black or ground pointer.
Now, attach the tip of the red pointer into the positive side of the battery while the black pointer goes to the negative polarity. If it happens that you did your connections in an opposite way, you will get a negative reading. But if you did it correctly, the voltage rating of the battery that you tested can be read on the screen of your multi meter tool.
Speaking about the screen, the DMM screen will directly display the numerical output. However, VOM displays its output on a scale so you really need to have a good eyesight.
As a second example, I suggest that you should try to read a resistor this time. A resistor component does not have a polarity so feel free to attach your pointers to any of its two legs.
When using a DMM, you will notice that the numerical output value on its screen display hardly fluctuates in value. It is very unstable that you can't decide what exactly are the last decimal digits. Now when it comes to the VOM, the reading that you will get is a lot more stable in value.
Let's go back to our battery example above. I have mentioned that when you attached the test probes in the wrong side or polarity of the battery, this will result into a negative value.
When using a VOM and let's say that you have mistakenly connected the test probes at the wrong sides of the battery, the needle on the scale will flip on the left side most indicating the value of "infinity" or "zero". But when it comes to the DMM, the output screen display will show the negative numeral voltage value of the battery.
Moreover, analog and digital multi meter tools have their own advantages and disadvantages. Based on my experience, I actually prefer to use the VOM for testing and trouble-shooting purposes. While, I use the DMM when working on something that really requires an accurate reading.
Multi Meter tool either analog or digital needs to be adjusted by pressing the buttons or rotating the knobs into the type of unit that you would like to read. In order to make an actual reading of a certain component, you have to use the two wired pointers which is a red and black color probes (more commonly known as "test probes"). The red colored pointer actually indicates positive polarity while the black colored pointer is the negative polarity or ground.
Let's say for example that you are going to read the voltage rating of a certain battery. Before you do, you have to make sure that you set the tool into the its proper "voltage" setting.
Next step is to hold the wired pointers with your hands. One pointer on each of your hand. If you are a right-handed person then it's best to always handle the red or positive pointer on your right while your left hand holds the black or ground pointer.
Now, attach the tip of the red pointer into the positive side of the battery while the black pointer goes to the negative polarity. If it happens that you did your connections in an opposite way, you will get a negative reading. But if you did it correctly, the voltage rating of the battery that you tested can be read on the screen of your multi meter tool.
Speaking about the screen, the DMM screen will directly display the numerical output. However, VOM displays its output on a scale so you really need to have a good eyesight.
As a second example, I suggest that you should try to read a resistor this time. A resistor component does not have a polarity so feel free to attach your pointers to any of its two legs.
When using a DMM, you will notice that the numerical output value on its screen display hardly fluctuates in value. It is very unstable that you can't decide what exactly are the last decimal digits. Now when it comes to the VOM, the reading that you will get is a lot more stable in value.
Reading Negative Unit Values with your Multi Meter Tool
Let's go back to our battery example above. I have mentioned that when you attached the test probes in the wrong side or polarity of the battery, this will result into a negative value.
When using a VOM and let's say that you have mistakenly connected the test probes at the wrong sides of the battery, the needle on the scale will flip on the left side most indicating the value of "infinity" or "zero". But when it comes to the DMM, the output screen display will show the negative numeral voltage value of the battery.
Moreover, analog and digital multi meter tools have their own advantages and disadvantages. Based on my experience, I actually prefer to use the VOM for testing and trouble-shooting purposes. While, I use the DMM when working on something that really requires an accurate reading.
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