Review on Dmyond Digital Display Voltmeter Multimeter Measuring & Layout Tools by Joe Griggs

It only took me a meter and I found that some of them were selling for six or seven dollars each. I was just wanting to save a dollar or two after reading reviews on several offerings, so I jumped at the opportunity to purchase these three packs for less than double the price of the individual packs. I bought these to use with my train model. Furnished. I have an experiment to do and decided to record the busbar voltages and currents during the test just to get some more interesting data. I have set a meter to match the voltage read by my DMM, but have not attempted to calibrate the current. My homemade PSU is mounted in a box, so I just cut another hole to fit the gauge. I later went back and calibrated the second of these gauges. Calibration was easy, if not questionable. For my setup I used a 12V power supply and a fan for the load. I connected the fan to the power supply as expected, but grounded both meters; panel and DMM. The DMM gave questionable results (the fan says it draws about 0.9A and I read about 0.3A) so I replaced it with an analog meter. I matched the voltage readings and then tested for current against a resistor. The digital gauge was still a long way from what was calculated, and then the analog gauge was almost right where it should have been. Getting the current to flow through both the panel meter and the multimeter was not easy. There would be no current if I fed a panel meter into the multimeter, but it would work if the multimeter was fed into the panel meter (both load to ground). The voltage was easy enough to set, although it requires a bias of 0.02 or 0.03 volts respectively. This one was a little more difficult. As soon as I touched the trigger cap (I assume it's up to the rest of this suggestion) the reading jumped almost 0.1A and then stabilized again as soon as I removed the screwdriver. I got it as close as possible, which is still about 0.05A, but it will be fine for my experiment. I went back and replaced the first meter with a more accurately calibrated second. The third counter is still in the package. Regarding the wiring to be used: the instructions aren't very clear on some things (nor were there any paper copies. I had to go back to this page to find the schematic). It states that the meter requires an external 4-25 volt power supply across the red and black wires, and then the current is measured across the black and red wires as well. I figured the connector that only had red and black was for current input and then the connector that had red, black and yellow was for current and voltage measurements. The two thicker wires - the plug with just the red and black wire - are for power, which makes sense considering it should read up to 10 amps. The other connector is the power supply to the device and the yellow wire is the voltage sensor.