Review on 🔧 AstroAI Digital Multimeter TRMS 4000 Counts: Accurate Voltage, Current, Resistance, and More! by Daniel Espinoza

After carefully researching the range of digital multimeters (DMM) I purchased four reasonably priced AstroAI TRMS 4000 gauges with similar products with similar functionality. These multimeters were purchased for use by middle and high school students participating in the National Science Olympiad program. The required features were easy to use, had an easy to read display, were accurate, and had acceptable fuzziness in a physical package that could withstand student abuse/abuse. Most DMMs in this price range since the TRMS 4000 did NOT have autoranging or were too small to have a reasonable display size. Meters with similar specs, including those from Fluke, Extech, and Amprobe, ranged in price from 10 to 2 times as much. Since I needed four, all of those meters were immediately ruled out. When the TRMS 4000 gauge arrived, a quick physical inspection showed it to be of solid construction with good markings and an LCD display about the size of my personal Fluke DMM I was holding . different batteries and 1% precision resistors to compare each meter's performance to my Fluke and each other. In all cases TRMS 4000 meters within +/- 4 LSBs in 3.5 digit mode and +/- 2 LSBs in 3 digit mode. With no real statistical analysis and no real NIST standards to back up, I'm confident that these gauges were accurate with an error that was within 1% +/- 1 digit in the tested ranges, which seems to correlate well with the AstroAI quoted specification . I should note that the results I got with the precision resistors were exactly as advertised. Since they are used for Science Olympiad competitions and general rules prohibit the use of dangerous voltages, I have not tested AC or higher DC voltage ranges. However, since I see excellent results with low DC voltage and resistance, I would feel comfortable using one of these as a professional troubleshooting tool for low frequency devices and devices. As the TRMS 4000 has a specified input impedance of 10MΩ I would not recommend it for use in sensitive instruments or high frequency circuits where a test input resistance of >100MΩ is recommended and typically required. I would also recommend not using handheld multimeters to directly measure currents greater than 1 amp even though they might be equipped to do so, external gates should be used for these types of measurements. a great choice for the serious hobbyist and student. If I had to do it all over again I would still buy these DMMs.