Digital Multimeters
Description
Digital multimeters or DMM are test equipments that measure voltage, resistance, current, and other possible electrical quantities like inductance, capacitance, etc. They are general purpose equipment and logical development of electric meters. The components of DMM are transistors, integrated circuits and display (either LED or LCD), terminals (red and black), and selector switch. Digital multimeters read out the exact measurement in number form on a LCD or LED display. Common features of DMM are analog bar graph, adjustable sampling rate, data acquisition, battery power, dB readings, data storage, removable data storage and triggering.
Operation
Once the digital multimeters are turned on, they self analyze their battery and internal circuits. The equipment that needs to be tested is connected through terminals to the digital multimeters. Then the selector switch is signaled to the measurement to be made and the readings displayed in LCD or LED displays are taken. The readings in display usually change for every 5 seconds in case of steady current and the optimized reading is considered.
Advantages
Digital multimeters offer the following advantages:
More versatile
Accuracy
No parallax errors as measurements are displayed
Built in overload protection
Digital multimeters measure both AC and DC currents (most analog multimeters cannot measure AC currents)
As a voltmeter, digital multimeters are better as they have high resistance
Auto ranging
Withstand mechanical shock better than analog multimeters as they do not consist of moving components
Applications
Digital multimeters are primarily used to test measurements very easily and quickly. LCD digital multimeters are important tool for technicians working with electronic equipments. In case of electrical trouble shooting in household and industrial devices like batteries, power supplies and motor controls, electric digital multimeters point out electrical measurements. Some advanced digital multimeters are employed in commercial and industrial applications for measuring circuit continuity and temperature.