Several Notes on Testing Digital Multimeter

(1) For high resistance, it is normal for the resistance test results to be different from the pointer meter test results. This is mainly due to slightly different test conditions.

(2) When testing physical quantities of related polarity, the polarity display corresponds to the test lead. That is, when the polarity is not displayed, the red test lead contact is the high potential end or the current inflow end, and when the polarity display is "-", the red test lead contact is the low potential end or the current outflow end.

(3) The resistance block and diode block are different from the pointer meter. When the pointer meter measures resistance, the red and black test leads are opposite to the test source polarity, that is, the black test lead is the positive end of the test source and the red test lead is the negative end. However, the digital meter is consistent with the test source polarity, that is, the red test lead is the positive end of the test source and the black test lead is the negative end, which is consistent with the voltage and current block. This will not cause confusion and is superior to the pointer meter.

(4) For transistors whose polarity or pin arrangement order is unknown, the electrodes of the transistor can be identified and determined by repeatedly changing the pins of the transistor through the HFE block.

(5) Calibration.
Digital multimeters should be calibrated regularly. When calibrating, a digital meter of the same type or with higher accuracy should be used. The calibration should be carried out in the order of first calibrating the DC range, then the AC range, and finally the capacitance range.

Digital multimeters often use a 9V laminated battery, which generally needs to be replaced after a few months of use. It is recommended to purchase a 9V rechargeable battery instead. This nickel-cadmium rechargeable battery model is GP-15F8K. It is exactly the same as a normal 9V laminated battery.