During maintenance, it is suspected through troubleshooting that the diode or transistor in the circuit may be damaged. But use a digital meter diode range to measure its conduction voltage of about 0.6V, with infinite reverse direction. No problem, even after checking the circuit, no faults were found. Why?
Solution: The test voltage emitted by most digital meter diode ranges from 3 to 4.5V. If the tested transistor has slight leakage or the characteristic curve has deteriorated, it cannot be displayed under such low voltage. At this point, it is necessary to use an analog meter with a resistance range of 10K, which emits a test voltage of 10V or 15V. At this test voltage, it will be found that the suspected transistor has leakage in the reverse direction. Similarly, when measuring the resistance of certain precision sensitive components with very low voltage resistance, using an analog meter can easily damage the sensitive components. At this point, a digital meter should be used for measurement.
3. Using a certain multimeter to measure the voltage value of the high-voltage probe after attenuation, it was found that the DCV test was more accurate, but the ACV error was large. Even when using a multimeter with high precision and precision, this is still the case. What is the reason for this?
Solution: The vast majority of multimeters measure voltage in parallel, and for the entire testing circuit, the voltmeter itself is equivalent to a load, which is the input impedance. The larger the load impedance, the less impact it has on the tested circuit, and the more accurate the test will be. But nothing can be perfect, as high impedance sacrifices the bandwidth of the test. At present, the input impedance of a multimeter with a frequency response of around 100KHz on the market is about 1.1M, so it will have a significant impact when testing the voltage of the high resistance load terminal 2, such as the high resistance value of the high-voltage probe itself. At this point, you need to choose a high internal resistance multimeter, such as the ESCORT 170/172/176/178/179 handheld digital multimeter, which provides an input impedance of up to 10000 Ω when testing ACV, in order to avoid this problem.
4. In actual testing, I need to measure not only voltage and current, motor winding impedance, etc., but also speed. Is there a multimeter that can achieve this function?
Explanation: The ESCORT-172 handheld digital multimeter can meet your above requirements, and its safety regulations comply with the International Electrotechnical Commission's IEC1010-1 CATII 1000V and CATIII 600V standards, so you can use it with confidence even in Class III environments without worrying about safety issues.
5. Is there a very cheap and reliable digital multimeter with stable performance?
Answer: There is such a good thing in the world, could you please tell me too. However, relatively speaking, the digital multimeters produced by ESCORT in Taiwan have a higher cost-effectiveness.
