Hengaode Instrument300VDigital AC millivolt meter‌working principle‌operating steps‌

It is an electronic instrument used for accurately measuring the effective value of AC voltage, and its operating principle involves multiple links such as signal processing, measurement, and display.‌

‌working principle‌

The core workflow of a digital communication millivolt meter includes signal input, amplification and attenuation, detection, analog-to-digital conversion, and display. The input signal is first protected against overload by an input protection circuit, and then conditioned by a preamplifier and an attenuation amplifier to meet the measurement requirements of different ranges.‌

2 The amplified signal is converted into a DC voltage by a linear detector, and then passed throughA/DConverter digitization, ultimately resulting inVFDThe display screen shows the measurement results.‌

1 This design ensures high precision and stability in measurement.

‌Basic operating steps‌

‌Power-on preparation‌Before operation, short-circuit the red and black crocodile clip of the input test probe and set the range switch to the range (e.g300V）To protect the instrument.‌

‌Power on and preheating‌After connecting the power, the instrument usually needs to be preheated10About seconds to ensure stability; It is normal for the pointer to swing irregularly during the preheating period.‌

‌Connection and measurement‌Connect the probe in parallel to the circuit under test (with the red clip connected to the positive terminal and the black clip connected to the ground terminal), and observe the position of the pointer. If the pointer deflection is too small, the range should be adjusted using the decreasing method to make the pointer point to the full range of the dial2/3Left and right to improve accuracy.‌

‌Reading method‌The dial contains scales for AC voltage effective value and decibel value. meet1Range (such as1mVThe10mVThe1V）From0—1Scale reading, every3Range (such as3mVThe30mVThe3V）From0—3Scale reading, the actual value is the scale indication multiplied by the range unit.‌

‌Key precautions‌

The instrument has high sensitivity and is susceptible to interference at low ranges, causing a "self starting phenomenon". Therefore, when not measuring, it should be switched to the high range.‌

Before measurement, short-circuit zeroing is required. If the pointer does not point to zero, the test line or zeroing potentiometer needs to be checked.‌

Only applicable for effective value measurement of sinusoidal AC signals; Non sinusoidal signals need to be converted.‌

The black clip at the input end must be reliably grounded to reduce interference.‌

The AC voltage range of a multimeter cannot be used as a substitute, as the input impedance of the multimeter is low and only suitable for measuring power frequency voltage.‌