History of the Digital Multimeter How the Digital Multimeter Works
Digital multimeters have evolved over time. Early multimeters used a dial with a magnetic deflection pointer, similar to the classic ammeter; Modern technology uses digital displays provided by LCD or VFD (Vacuum Fluorescent Display). It is not difficult to find analog multimeters in the second-hand market, but they are not very accurate because both zeroing and accurate readings from the dashboard can easily cause deviations.
Digital multimeter history
The digital multimeter has gradually developed through history. Early multimeters used a dial with a magnetic deflection pointer, similar to the classic ammeter; Modern technology uses digital displays provided by LCD or VFD (Vacuum Fluorescent Display). It is not difficult to find analog multimeters in the second-hand market, but they are not very accurate because both zeroing and accurate readings from the dashboard can easily cause deviations. Some analog multimeters use vacuum tubes to amplify input signals, and this type of multimeter is also known as a vacuum tube voltmeter (VTVM) or vacuum tube multimeter (VTMM), VacuumTubeMultimeters). Modern multimeters have been fully digitized and are specifically referred to as Digital Multimeters (DMMs), DigitalMultiMeter). In this device, the measured signal is converted into a digital voltage and amplified by a digital preamplifier, and then directly displayed on a digital display screen; This avoids the deviation caused by parallax during reading. Similarly, better circuit systems and electronics have also improved measurement accuracy. The basic accuracy of old analog instruments is between 5% and 10%, while modern portable digital multimeters can achieve ± 0.025%, and workbench equipment has an accuracy of up to one millionth.
Working principle of digital multimeter
The basic circuit of a digital multimeter is a header circuit, which quantifies the input DC voltage (analog) and outputs it; Other functions generally require the addition of external circuits. Nowadays, the integration of multimeter chips is increasing, and the number of peripheral circuits is decreasing. This has both advantages and disadvantages. Advantages: High integration, simple external circuits, and fewer quality failures caused by component quality issues; Disadvantage: Once the chip breaks down, the replacement cost is high and troublesome. Sometimes, the money spent on replacing one chip can be used to buy another instrument, so usually it has to be scrapped.
