Error Analysis of Resistor Measurement by Voltage Semi-bias Method

【Overview】

The voltage half-bias method is a commonly usedresistanceThe measurement method is widely used in electronic experiments and circuit testing because of its easy operation and high measurement accuracy. However, in the actual measurement process, the voltage semi-bias method will inevitably be affected by various error factors, causing the measurement results to deviate from the true value. This article will systematically analyze the main sources of errors when measuring resistance using the voltage semi-bias method, discuss their generation mechanisms and improvement measures, and help engineers and technicians improve measurement accuracy.

1. Brief description of the measurement principle of voltage semi-bias method

The voltage half-bias method adjusts the voltage divider in the circuit so that the voltage across the resistor under test reaches half of the voltage source voltage, thereby calculating the resistance value. This method takes advantage of the symmetry of the voltage distribution to simplify the measurement process and avoid the complexity of directly measuring the current.

2. Error caused by unstable power supply voltage

The voltage semi-bias method relies on a stable supply voltage as a reference. If the power supply voltage fluctuates or the noise is large, the voltage at the voltage dividing point will be inaccurate, which will affect the judgment of the half-bias point and ultimately cause resistance measurement errors.

3. Influence of internal resistance of voltmeter

The internal resistance of a voltmeter cannot be infinite, especially when using a traditional analog voltmeter. The low internal resistance will shunt part of the current and change the actual voltage distribution in the circuit, causing deviations in the measurement results.

4. Connection wire and contact resistance errors

During the measurement process, the resistance of the connecting wire and the oxidation or looseness of the contact points will add additional resistance value. This part of the impedance is not considered, which directly affects the accuracy of the voltage division and causes measurement errors.

5. Effect of temperature change on resistance value

The resistance values ​​of both the resistor being measured and the measuring circuit components change with temperature. Fluctuations in ambient temperature or heating of components during measurement may cause resistance deviations, thereby affecting the accuracy of the measurement results.

6. Oscilloscope or digital voltmeter sampling error

In modern measurements, digital voltmeters or oscilloscopes are commonly used to collect voltage signals. Improper settings of sampling frequency, resolution and range may introduce quantization errors and sampling noise, affecting the judgment of the half-bias voltage point.

7. Deviation of circuit component parameters

In actual circuits, there is a certain deviation between the nominal values ​​of resistors, capacitors and other components and the actual values. In particular, the error of the voltage divider resistor directly affects the determination of the half-deflection point, resulting in measurement errors.

8. Operator reading error

Human factors are also one of the important sources of errors, including parallax and adjustment when observing readings.PotentiometerInaccuracies, etc. may cause deviations in the measurement results.

9. Frequency and communication effects

In AC power measurements or high-frequency signal environments, inductance and capacitance effects are significant, and the DC measurement principle of the voltage semi-bias method is not fully applicable and will introduce additional errors.

【】

The voltage semi-bias method is a simple and effective resistance measurement method. Its measurement accuracy is affected by many factors such as power supply stability, voltmeter internal resistance, connection resistance, temperature changes, sampling equipment, component parameters and human operation. By selecting high-quality power supplies and measuring instruments, optimizing circuit design, maintaining good contact conditions, controlling ambient temperature and standardizing operating procedures, errors can be effectively reduced and measurement accuracy and reliability improved. In the future, combined with digital technology and intelligent algorithms, it is expected to further improve the measurement performance of the voltage semi-bias method.