0 basic introduction to single chip microcomputer: how to use digital multimeter and precautions

How to play with digital multimeter with zero basis

The multimeter is a multi-function 、 Multi range measuring instrument , It can be used to measure AC and DC current 、 AC / DC voltage 、 resistance 、 Triode magnification , Some can also measure capacitance 、 Inductance and other parameters .

First of all, let's understand the precautions of digital multimeter

1： Do not select the wrong gear when measuring current and voltage , If the resistance gear or current gear is used to measure the voltage , It is very easy to burn the meter .

2： When the multimeter is not in use , It is best to turn the gear to the highest gear for measuring AC voltage , Avoid damage due to improper use .

3： If you don't know the magnitude of the measured voltage or current , The highest grade should be used first , Then select the appropriate gear for measurement , The closer the selected gear is to the measured value , The more accurate the measured value is .

4： When measuring resistance , Do not touch the bare ends of the components with your hands , So as to prevent the human body resistance and the measured resistance from being connected in parallel , Make the measurement result inaccurate .

Now let's talk about the use of digital multimeter

Use of resistance gear ： The resistance gear has an ohmic symbol , Indicates measuring resistance , When measuring gear, first judge the measured resistance , Then select the range , If you don't know how much resistance , An intermediate gear can be selected for trial measurement , Then change the gear according to the measured value , There is no difference between positive and negative resistance , Connect the red and black probes to both ends of the resistor .

Use of voltage range ： Turn the knob to the voltage level , Before measuring, we must first judge whether the voltage we measure is AC or DC , If the selected gear is not of the type to be tested , You can press AC 、 DC change gear is the multimeter DC/AC Shift gears . Some multimeter DC and AC are separated , This multimeter does not change the gear button , In addition, it is necessary to select a suitable measuring range , If you do not know the voltage to be measured before the measurement , Be sure to choose the maximum range .

Use of current gear ： Turn the rotary switch to the current position , Determine whether you want to measure DC or AC , After confirmation , According to the estimated current , Insert the red probe into the corresponding milliampere or microampere or 20 Amp Jack , The black probe is connected to com terminal , Then disconnect the circuit , Connect the probes in series behind the circuit , The multimeter will display the measured current .

Use of capacitor gear ： Turn the function knob to capacitance F, And select the appropriate range , Put the probe on both ends of the capacitor , Don't divide the positive and negative poles , The capacitance at this time can be directly read out on the display screen . Pay attention to discharge the capacitance before and after measurement , When measuring large capacitance, it needs to be stable for a period of time before reading .

Use of diode block ： We can use the diode to measure the on-off of the circuit and the voltage drop of the diode , Turn the knob to the diode identifier position , Then short the lead , Hear the buzzer , It indicates that it can be used normally , We also use this point to measure whether the circuit is open . When measuring diode voltage drop , The red probe is connected to the anode of the diode , The black probe serializes the cathode of the diode , The display will show the pressure drop value , It can be used to judge whether the diode is a silicon tube or a germanium tube , And whether the diode is damaged .

Use of triode stop ： Turn the knob to HFE In gear , It is the gear for measuring the amplification parameters of the triode , There are generally two kinds of jacks ,NPN and PNP, In distinguishing NPN Type triode is still PNP After the type a triode is inserted into the corresponding jack display screen according to the pin name, the magnification of the triode will be displayed .

Use of frequency gear ： Measure on the frequency meter board , Ten megahertz represents the maximum frequency value that can be measured , When measuring , Connect the probe to both ends of the frequency meter , The measured value can be read out on the display . The red probe should be connected to the positive pole of the signal source , The negative pole is connected to the negative terminal of the signal source . The frequency sensitivity of digital multimeter is not very high , If the frequency signal below several hundred millivolts is measured , Generally, the signal is amplified and then measured , For signals with more than dozens of amplitude, it is necessary to attenuate through resistance partial voltage before measuring .

Today, I will share some related knowledge about multimeter , Like to help collect some praise , Thank you for your support and encouragement ！

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