09,22,2026 15 views
The measurement technology used in the circuit resistance tester plays a very important role in electronic and electrical support. For example, in technical support and maintenance work, it is often necessary to measure the resistance of the circuit, and to regularly detect the contact resistance of relays, contactors, buttons, switches and other contacts, as well as equipment with high failure rates. The contact resistance value of the contacts is controlled within a certain range, so that operators can grasp the quantitative changes of the equipment and eliminate faults in the bud. And the resistance of such resistors is often in the micro ohm range, which cannot be measured with a multimeter. The portable digital micro ohm circuit resistance tester designed in this project has the advantages of high accuracy, stable reading, good reliability, and easy operation, and has strong practicality.
The basic principle of circuit resistance tester equipment:
Use a specific current source to provide a test current of 100A or more, apply it to the circuit resistance to be tested, and use a signal sampling circuit to collect voltage and current signals on both sides of the circuit resistance. The obtained signal is amplified by an amplifier, then subjected to A/D conversion and microprocessor processing, and finally processed by a microcontroller to obtain the desired value, which is then sent to a display device to display the measured resistance value.
Design specifications for each component of the equipment:
1. The determination of design tasks mainly includes the selection of power supply, the application of integrated operational amplifiers and A/D conversion circuits, as well as the application of microcontrollers, including measurement and acquisition, the use of liquid crystal display modules, the requirement to be able to print output and complete electronic circuits using Pro, and the computer-aided design of circuits using design software.
2. Design of hardware circuit: After understanding the design tasks and functions of the circuit resistance measuring instrument, we will decompose the design tasks of the circuit resistance measuring instrument into several topics according to functional modules, and then carry out specific designs one by one. Including the selection of microcontroller, the design of microcontroller reset circuit, the design of microcontroller clock circuit, the design of microcontroller memory expansion, microcontroller I/O expansion design, etc.
3. The design of the measurement part (data acquisition system): After fully considering various factors and selecting the microcontroller, the design of input and output interfaces and other functional components also needs to be carried out. The selection from preamplifier to sample and hold amplifier, and then to digital to analog converter.
4. Human machine interface circuit design: Intelligent instruments receive various commands and data through human machine components and devices, and provide calculation and processing results. Human machine components usually include keyboards, displays, etc.
5. Overall design of system software: Based on the hardware design content, we design the corresponding software. Software design is divided into six modules: parameter setting module, data acquisition module, data analysis and processing module, control output module, and data management module. This achieves the functions of various hardware components of the circuit resistance tester.
