Multimeters are widely used, and now take the popular digital meters and pointer meters as examples. Introduce its use and precautions for the reference of electronic beginners.
1. Routine use and maintenance First turn on the power, and then select the measured object is voltage, current, resistance or other quantities. The next step is the range. When the parameters cannot be determined, it can be set to the maximum range, and then gradually reduce the range. Before measuring, you should also check whether the test leads are in the correct hole position. Use moderate force when turning the range switch to avoid possible damage to the metal sheet of the switch. After use, the function range switch is best placed in the high pressure block.
2. A few notes on the test
(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 the physical quantity of relevant polarity, its polarity display corresponds to the test lead. That is to say, 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 shows "-", the red test lead contact is the potential low end or the current outflow end. (The pointer type multimeter should pay attention to the red and black test leads can not be reversed, red is the potential high-end or current inflow end)
(3) Electric block and diode block are different from pointer watch. When the pointer meter measures resistance, the red and black test leads are opposite in polarity to the test source, 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 polarity of the digital meter is the same as that of the test source, 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 blocks.
(4) For triodes whose polarity or pin arrangement order is unknown, the electrodes of the triodes can be identified and determined by the multiple pin-change detection of the HFE block of the triode.
3. Expansion of use and power supply substitution The expansion is mainly to expand its measurement function, which is difficult to a certain extent. Readers can measure high voltage, large current, micro current, frequency, temperature, etc., as long as they refer to relevant materials and make some conversion circuits. Used as a test signal source.
