What is the Advantage of having Autoranging on a Digital Multimeter?


Autoranging multimeter                     Manual ranging multimeter

    Figure: A  Digital Multimeter                                      Figure: A Manual Ranging
          with Autoranging                                                      Digital Multimeter


Autoranging is a great advantage to have on a digital multimeter. Autoranging saves you the hassle of having to know which range of value the resistance, capacitance, voltage or whatever electrical characteristic you’re finding falls under. The multimeter finds the value for you. With a manual ranging multimeter (no autoranging), there are preset ranges, and you have to know which range of value your component falls under to get the value reading.

Say, you have a resistor:

20M resistor

If you don’t know how to read the color code of a resistor, you basically have no idea which range of resistance it falls in. With a manual ranging multimeter, you would just have to keep measuring the resistor by flipping from one range to the next until you are in the correct range and get a reading. Typical ranges of resistances on a manual ranging multimeter are 0-200Ω, 200Ω-2KΩ, 2KΩ -20KΩ, 20KΩ -200KΩ, 200KΩ -2MΩ, 2MΩ -20MΩ. If you had started from the first resistance range, you would have switched the notch 5 times before you got the readout of 20MΩ ±5%, which is what the above resistor is, since it falls into the last range of 2MΩ-20MΩ. With autoranging, all you do is switch the notch to the ohmmeter (resistance reading), with no need to adjust any ranges within the resistance, and you would have gotten the digital value readout automatically. This is the advantage of a DMM with an autoranging feature. It saves the hassle of switching through various preset ranges and finds the value automatically for you.

Autoranging multimeters are more expensive but well worth the price. Even if you are proficient at reading the color code of resistors and other electrical components, it’s still a good idea to have one. For one, a component could be bad. You might have the manual ranging multimeter on the range of what the component should be, but if it's bad, it can literally be in any range. To save the hassle of switching from range to range to find its value, an autoranging multimeter will find it automatically for you. Another prime example of using an autoranging multimeter is when troubleshooting a circuit for voltage. If you’re reading the voltage of a circuit and you’re expecting a value of around 5V, you’re going to have the DC voltmeter in the range of 2V-20V when in actuality, if your circuit is bad, it can be below that range or if something is really wrong, above that range. This is why it’s a good idea to have an autoranging multimeter. But rest assured, if you can’t get one, a manual ranging multimeter can work just fine. 



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