Measuring range of the technical characteristics of the multimeter
(1) AC and DC voltage (AC frequency is 45Hz～500Hz); the ranges are 200mV, 2V, 20V and 1000 respectively, the DC accuracy is below ±(0.8% of the reading+2 digits), and the AC accuracy is ±(of the reading 1%+5 characters); input impedance, DC file is 10MΩ, AC file is 10MΩ, 100PF.
⑵ AC and DC current
The measuring ranges are 200μA, 2mA, 200mA and 10A. The DC accuracy is ±(1.2% of the reading+2 digits), the AC accuracy is ±(2.0% of the reading+5 digits), and the maximum voltage load is 250mV( AC rms).
⑶ Resistance:
The measuring ranges are: 200Ω, 2kΩ, 200kΩ, 20MΩ and 20MΩ six levels. The accuracy is ±(2.0% of reading+3 digits).
⑷Diode conduction voltage:
The measuring range is 0~1.5V, and the test current is 1mA±0.5 mA.
(5) Transistor β value detection:
The test conditions are: VCE=2.8V, IB=10μA.
⑹Short circuit detection:
Test circuit resistance <20Ω±10Ω
Measuring Resistance of Digital Multimeter
Insert the red test lead into the "V/Ω" jack, select the appropriate resistance measurement range according to the size of the resistance, touch the red and black test leads to both ends of the resistance, and observe the reading. In particular, when measuring the resistance on the circuit (the resistance on the circuit board), the power supply of the circuit should be turned off first, so as not to cause the reading to jitter. It is forbidden to use resistance gear to measure current or voltage (especially AC 220V voltage), otherwise it is easy to damage the multimeter. In addition, the resistance file can also be used to qualitatively judge whether the capacitor is good or bad. First short-circuit the two poles of the capacitor (touch both poles with a test lead at the same time to discharge the capacitor), then touch the two test leads of the multimeter to the two poles of the capacitor respectively, and observe the displayed resistance reading. If the resistance reading displayed at the beginning is very small (equivalent to a short circuit), then the capacitor starts to charge, the displayed resistance reading gradually increases, and finally the displayed resistance reading becomes "1" (equivalent to an open circuit), indicating that the capacitor is OK If the above steps are followed and the displayed resistance reading remains unchanged, it means that the capacitor is damaged (open circuit or short circuit). Special attention should be paid to the selection of the appropriate resistance range according to the size of the capacitance when measuring, for example, 200k range for 47μF, 2M range for 4.7μF, etc.
