Electronic manufacturing and repair field,resistancePrecise measurement is crucial. High-precision resistance measuring instruments on the market are expensive and have complicated functions, which are not very friendly to enthusiasts and beginners. Therefore, DIYing a high-precision resistance measuring instrument can not only save costs, but also improve hands-on ability and depth of understanding. This article will introduce in detail how to make a high-precision resistance measuring instrument, from design principles to production steps, to help you easily achieve accurate measurements.
1. Understand the working principle of high-precision resistance measuring instrumentHigh-precision resistance measuring instruments mainly measure the voltage and current at both ends of the resistor and use Ohm's law to calculate the resistance value. In order to improve the measurement accuracy, a constant current source is usually used for power supply to avoid errors caused by voltage fluctuations. At the same time, the instrument needs to have high-resolution voltage and current sampling capabilities, as well as good anti-interference design.
2. Select the appropriate measurement circuitCommonly used circuits for DIY measuring instruments include the Wheatstone bridge and the four-wire measurement method. The Wheatstone bridge achieves high-precision measurement through balanced circuits and is suitable forLow value resistor; The four-wire measurement method uses two wires to supply power and measure voltage using two wires, eliminating the influence of lead resistance and is particularly suitable for micro-ohm resistance measurement. Choosing an appropriate circuit solution based on needs is the key to ensuring measurement accuracy.
3. Use high-precision electronic componentsHigh-precision measurement is inseparable from high-quality components. The resistor must be a standard resistor with low temperature drift and low noise. The operational amplifier in the current source part should have low bias current and low noise characteristics. In addition, the use of high-precision analog-to-digital converters (ADCs) improves the resolution and stability of data sampling, which helps improve the overall measurement accuracy.
4. Design a stable constant current sourceThe constant current source is the core component to ensure stable measurement. Commonly used designs include a constant current source circuit composed of an op amp and a power transistor, which can provide stable and adjustable current. By adjusting the current size, it can adapt to the measurement needs of different resistance values. The stability of the constant current source directly affects the repeatability and accuracy of the measurement results.
5. Establish a good shielding and grounding systemResistance measurements are extremely sensitive to interference, especially when measuring with high precision. Reasonable shielding design can effectively reduce electromagnetic interference, and a good grounding system prevents ground wire current from affecting measurement results. Shielded wires and metal casings should be used during production to ensure that the instrument works stably in various environments.
6. Design friendly user interface and displayThe ease of use of DIY measuring instruments cannot be ignored. Equipped with an LCD display or OLED display module to display measurement data in real time to enhance user experience. Use buttons or knobs to adjust parameters, and even use microcontrollers for data processing and storage to facilitate subsequent analysis and recording.
7. Calibration and error correction methodsHigh-precision measuring instruments require regular calibration. Calibrate using known standard resistors to correct system errors. Temperature compensation and nonlinear error correction are implemented through software algorithms to further improve measurement accuracy. A calibration interface should be reserved during the production process to facilitate maintenance and upgrades.
8. Production and debugging skillsKeep the circuit clean and tidy when welding to avoid stray capacitance and inductance affecting the measurement. During the debugging process, the functions of each module are gradually verified to ensure that the constant current source, voltage sampling and data processing are normal. It is recommended to use an oscilloscope and multimeter to assist in testing to find and eliminate potential problems.
DIY high-precision resistance measuring instrument can not only meet the needs of electronic enthusiasts for accurate measurement, but also improve personal electronic design and production capabilities. By understanding the measurement principle, selecting appropriate circuits and components, designing the constant current source and shielding system, and improving the user interface and calibration methods, you will have a homemade resistance measuring instrument with stable performance and accurate measurement. I hope the introduction in this article can provide you with powerful guidance on your DIY journey and help you easily create an ideal high-precision measuring tool.
