How to use a digital multimeter
Compared with analog instruments, digital instruments have high sensitivity, high accuracy, clear display, strong overload capacity, easy portability and simpler use. Take the VC9802 digital multimeter as an example to introduce the usage and precautions of the digital multimeter.
1. How to use the digital multimeter
a. Before use, you should read the relevant instruction manual carefully and be familiar with the functions of the power switch, range switch, jack, and special jack.
b. Put the power switch in the ON position.
c. Measurement of AC and DC voltage: Set the range switch to the appropriate range of DCV (DC) or ACV (AC) as required, insert the red test lead into the V/Ω hole, the black test lead into the COM hole, and connect the test lead to the line under test in parallel , the reading is displayed.
d. Measurement of AC and DC current: turn the range switch to the appropriate range of DCA (DC) or ACA (AC), insert the red test lead into the mA hole (<200mA) or the 10A hole (>200mA), and insert the black test lead into the COM hole , and connect the multimeter in series with the circuit under test. When measuring DC, the digital multimeter can automatically display the polarity.
e. Resistance measurement: turn the range switch to the appropriate range of Ω, insert the red test lead into the V/Ω hole, and the black test lead into the COM hole. If the measured resistance value exceeds the maximum value of the selected range, the multimeter will display "1", and a higher range should be selected at this time.
When measuring resistance, the red test lead is the positive electrode, and the black test lead is the negative electrode, which is the opposite of the pointer type multimeter. Therefore, when measuring components with polarity such as transistors and electrolytic capacitors, you must pay attention to the polarity of the test leads.
