July 14, 2010- Multimeters are fast becoming popular for their easy-to-use quality desirable for DIY electronics projects (such as solving home and automobile electrical and electronic problems.) A Multimeter is a combination of voltmeter, ammeter, resistance meter and some other types of electronic meters. These multimeters are also known as VOM – an abbreviation that stands for Volt-Ohm-Milliampere Meter. Regarding their demand in the market, electronic devices manufacturers keep on introducing many types of multimeter. However, not all of them can be said to be up to the mark or even useful for household purposes. So, before buying a multimeter, it is always good to know at the first place as to how to buy a multimeter. Here we give some tips to choose a VOM or the popular Volt-Ohm-Milliampere Meter!

Choosing a Multimeter

First of all you must decide whether you want a digital meter or an analog meter (or both.) You must also make it clear to yourself about what do you want when talking about the accuracy of voltmeter or other meters combined in VOM, functionality, calibration, and the quality of multimeter. Having all these in mind, you must also know about the advantages and disadvantages of both- analog and digital multimeter.

Analog Multimeter- Benefits and Drawbacks

Analog multimeter is the 'old style moving-needle' multimeter. Useful features of an analog multimeter include its measurement ranges. When you buy an analog meter, the more ranges it has, better will be the chances of it to be used close to full scale deflection for high accuracy. The less sensitive 200 micro amps range is more commonly used.

Advantages of Analog Multimeter

• It can measure fluctuations and transients even low frequency fluctuations, to a certain extent.
• Analog multimeter doesn't need batteries. If you need just to use voltmeter and ammeter than you can consider analog multimeter but if you are going to use the resistance meter, you will need batteries too.
• Analog multimeter can be read fast as the needle reacts quickly. So, if you want to buy a multimeter for fast probing of multiple points, it can prove to be just what is required.
• Analog multimeter is also efficient in tuning electronic circuits to a specified value like when setting a trim or variable resistor is needed. This is possible because of the speed and relative position of the needle that can give helpful feedback.

Disadvantages of Analog Multimeter

• Analog multimeter has a limited accuracy rate. Its accuracy ranges from plus or minus 1% to 4% of full scale. A reading in the middle of the scale (half full scale) has half the accuracy (2% to 8%)
• Absence of automatic ranging- the multimeter has to be manually set to get the needle almost at maximum (full scale deflection). This can only give precise readings.
• There is always a possibility of mistake in reading the wrong scale. Scale can as well get difficult to read.
• Analog multimeter is also delicate as is the needle's mechanism. Accuracy can get affected if the multimeter is dropped.

Digital Multimeter- Benefits and Drawbacks

Digital multimeter has many useful features like automatic power-off, back-lit display having "always on" option, analog bar graph for quick reading of fluctuations (it is available on professional multimeter models that are very expensive though as it provides the advantages of both analog and digital meters), options for auto or manual ranging, display of minimum, maximum and average readings, measurement hold feature, provision for connection to PC for automatic periodic data-logging, automatic AC/DC voltage detection and measurement switching, non-contact AC voltage detector to identify live wires etc. With all such useful features, no wonder that digital millimeter is gaining popularity day by day. However, it has its own set of advantages and disadvantages too.

Advantages of Digital Multimeter

• Accuracy is the foremost advantage of a digital multimeter. The best quality digital multimeter has accuracies as high as plus/minus 0.1% but 1% to 2% is more common.
• Digital multimeter is easy to use. Autoranging digital multimeter automatically switches the internal circuit to the correct measuring range that is a great benefit for the users.
• Advanced digital multimeter can measure waveform frequency and duty cycle (edging into oscilloscope territory.)

Disadvantages of Digital Multimeter

• Most of the digital multimeter models have LCD display. These LCD screens can be sometimes very dim to read easily. Models having a backlit display are a solution for this but they decrease battery life.
• Digital multimeter is also not suitable for measuring fluctuations and transients.
• Digital multimeter also do not has zero adjustment for resistance measurement, except on advanced models.

Which is the Best Multimeter to Buy?

After going through the benefits and drawbacks of both- analog multimeter and digital multimeter- some of you might still be thinking about the best buy regarding a VOM multimeter. Now, the answer to that depends upon your suitability of requirement as well as capability of handling a particular type of multimeter.

If you are a non technical person who want to buy multimeter for DIY electronic projects, a basic, low-price autoranging digital multimeter is the one that you must buy as it is easy to use

If you are among the advanced DIY user and are able to handle the complexity of an analog multimeter, you can go for one. You must be then prepared for dealing with fluctuating readings.

If you are a professional user- engineer, technician or electrician- you can consider buying a digital multimeter with a bar graph display. This will let you have the advantages of both types of multimeters. You can even buy hybrid multimeter with dual digital and analog displays though it is a costlier option.

If you want to buy a multimeter just for checking batteries, then buy a battery tester instead of a multimeter. It is far more easier to use and will give value for your money.