9 Things to Know About Using a Digital Multimeter
(1) When measuring resistance with a multimeter ohm gear, remember not to carry electricity to measure, and the measured resistance can not have parallel branch circuit.
(2) Measurement of resistance value is relatively large resistance (such as 10M resistance) should be the first two pens short-circuited, the value displayed at this time may be 1M. each measurement is required to subtract the results of this value, the actual resistance value. (The error will be bigger when the resistance is high).
(3) Analogue multimeter and digital multimeter internal power supply and red and black pen connection:
(4) When the size of the measured voltage (or current) cannot be estimated beforehand, it should be dialled to the highest range for a trial test, and then select the appropriate range according to the situation.
(5) If the highest position of the multimeter during the test shows the number "1", and the other positions are fading, it proves that the instrument has been overloaded, and a higher range should be selected.
(6) Measurement of current when the input current exceeds 2A, the red pen should be reconnected to the "10A" jack, the hole is generally not added to the protection device, so the measurement of high current time shall not exceed 10 ~ 15s, so as to avoid manganese-copper shunt resistor heating changes in the resistance value, affecting the accuracy of the readings.
(7) Avoid operational malfunctions, such as measuring voltage with current gear, measuring voltage or current with resistance, measuring charged capacitors with capacitance gear, etc., so as not to damage the instrument.
(8) At the beginning of the measurement, the instrument will appear to jump the number of phenomena, should wait for the display value to stabilise before measurement.
(9) Measurement of resistance, diode, check the line through, the red pen should be connected to the V-Ω jack, this time the red pen with a positive charge, the black pen connected to the COM jack with a negative charge, which is opposite to the analogue meter resistance block. Detecting diodes, transistors, light-emitting diodes (LEDs), electrolytic capacitors and other components with polarity, you must pay attention to the polarity of the pen.
