![]() Instead, the ADC uses a buffering and averaging strategy on the samples to achieve high accuracy and resolution. Operations flow diagram around the ADC of a digital multimeterĪlthough the ADC will take many samples, the overall digital multimeter will not display or return every sample it takes. Figure 3 shows a simplified operations flow of the ADC’s sample acquisition process within a DMM.\įigure 3. In the case of some handheld multimeters, some of these blocks may be implemented in a VLSI circuit where the ADC and the display driver appears in the same integrated circuit.Īlthough the ADC forms the key element within the instrument, to fully understand how a DMM works, you need to look at some of the other functions around the ADC. The block will coordinate all the internal functions and transfer information to external devices such as printers, portable computers, or other test instruments. The digital controller block is implemented with either a microcontroller or a microprocessor, managing the flow of information within the instrument. The ADC then converts the pre-scaled DC voltage into its equivalent digital numbers which will be displayed on the display unit. The block diagram in Figure 2 shows a typical digital multimeter, where the input signal AC or DC voltage, AC or DC current, resistance, temperature, or any other parameters is converted to DC voltage within the range of the internal analog-to-digital converter (ADC). Simplified working principle of a digital multimeter Portable handheld DMMs are even smaller, lighter, and are battery-operated.įigure 2. ![]() Notably, they pack a lot of functions into a small benchtop box, typically no bigger than the size of a book. DMMs are programmable and can communicate with external computers for post-analysis work. Modern digital multimeters are highly versatile and can make multiple types of measurements and provide graphical output displays, such as trends and statistical charts. From left, an HP 3406A analog voltmeter, HP 2401C digital voltmeter, and Keysight 34470 digital multimeter How to use a digital multimeter With digital technology, multimeters provide graphical displays, perform data logging and signal digitizing capabilities, offer programmability, and communicate with external devices.įigure 1. A modern digital multimeter (DMM) uses digital and logic technology to miniaturize and enable many features in its internal system. ![]() What is a digital multimeter?Ī multimeter is a measuring meter that makes multiple types of measurements such as alternating current (AC) or direct current (DC) voltage, AC or DC current, resistance, temperature, capacitance, and other parameters. Digital multimeters (DMMs) started replacing analog multimeters in the 1950s due to their accuracy and extra features such as auto-ranging, data logging, and more. Multimeters have come a long way since the invention of galvanometers, an analog needle-pointing display measuring voltage and resistance in the 1820s.
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