The multimeter is a combination of voltmeter, amperemeter, and ohmmeter in a single instrument. Multimeter, that is commonly known as VOM (Volt-Ohm Meter, is differentiated by two type which are analog multimeter and digital multimeter.
ANALOG MULTIMETER (AMM)
This type of a multimeter is basically a moving coil instrument. An analog multimeter will have a scale with numbers on it. When you are testing something, such as the voltage of a 12 volt car batter, a needle will move and point to how many volts that battery has (around 12 if it is fully charged).
How to read analog multimeter (retrieved from http://www.wikihow.com/Read-a-Multimeter)
1. Set the range on your analog multimeter.
2. Determine the value of the maximum reading. The maximum reading equals the range that you set on your dial. If you set your dial at 200 volts, then this multimeter reading is showing 200 volts.
3. Calculate the reading at half scale. The reading at half scale equals the volt range divided by 2. If your multimeter is set to 200 volts, then this reading indicates an output of 100 volts.
4. Calculate the reading at different points along the scale. If your range is 200 volts and your needle points to 0.72, then the reading is at 0.72 x 200, or 144 volts.
DIGITAL MULTIMETER (DMM)
A DMM has a digital display and a function selector switch. The range selection takes place automatically.
COMPARISON BETWEEN ANALOG AND DIGITAL MULTIMETER
In analog multimeters, visual indication of changes in the reading is not good due to the effect of damping torque. Whereas in a digital multimeter, an excellent visual indication of changes in reading is acquired.
Analog multimeters are accurate, but not as much as the digital multimeter due to the magnetic effect in the coil being degraded after usage. Digital multimeters are highly accurate compared to analog.
An analog multimeter is less costly compared to the digital counterpart due to a simple construction and no power supply being required. But in the case of a digital multimeter, it is far more expensive than the analog multimeter and has a complicated construction, and also requires a power supply.
In an analog multimeter, the range has to be adjusted by the user. Whereas in a digital multimeter, the range is adjusted automatically.
In a digital multimeter, the mechanical handle can be easily rotated to tune the circuit to its peak.
Source :
Petruzella, Frank D. 1996. Industrial Electronics. Singapore: McGraw Hill
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