Steps to use an oscilloscope to observe the waveform of an electrical signal

　　The oscilloscope is an electronic measuring instrument with a wide range of uses. It can transform invisible electrical signals into visible images, making it easier for people to study the changing process of various electrical phenomena. The oscilloscope uses a narrow electron beam composed of high-speed electrons to hit the screen coated with fluorescent material to produce tiny spots of light. Under the action of the measured signal, the electron beam is like the tip of a pen, which can draw the changing curve of the instantaneous value of the measured signal on the screen. The oscilloscope can be used to observe the waveform curves of various signal amplitudes changing with time, and it can also be used to test various different electrical quantities, such as voltage, current, frequency, phase difference, amplitude modulation, etc.
　　
　　Before the oscilloscope is used for the first time or when it is reused for a long time, it is necessary to conduct a simple inspection of whether it can work and adjust the stability of the scanning circuit and the DC balance of the vertical amplifier circuit. When the oscilloscope performs quantitative tests on voltage and time, the vertical amplifier circuit gain and horizontal scanning speed must also be calibrated. The inspection method for whether the oscilloscope can work normally, the calibration method for the vertical amplification circuit gain and the horizontal scanning speed, because the amplitude, frequency and other parameters of the calibration signal of various models of oscilloscopes are different, the inspection and calibration methods are slightly different.
　　
　　The oscilloscope can be used to observe the waveform curves of various different electrical signal amplitudes changing with time. On this basis, the oscilloscope can be used to measure electrical parameters such as voltage, time, frequency, phase difference and amplitude modulation. The following introduces the steps of using an oscilloscope to observe the waveform of electrical signals.
　　
　　1. Select the Y-axis coupling mode
　　
　　According to the frequency of the measured signal, set the Y-axis input coupling mode selection "AC-ground-DC" switch to AC or DC.
　　
　　2. Select the Y-axis sensitivity
　　
　　According to the approximate peak-to-peak value of the measured signal (if an attenuation probe is used, it should be divided by the attenuation multiple; when the coupling mode is set to DC, the superimposed DC voltage value should also be considered), set the Y-axis sensitivity selection V/div switch (or Y-axis attenuation switch) to the appropriate level. In actual use, if it is not necessary to read the voltage value, the Y-axis sensitivity fine-tuning (or Y-axis gain) knob can be appropriately adjusted to make the required height waveform appear on the screen.
　　
　　3. Select the trigger (or synchronization) signal source and polarity
　　
　　Usually, set the trigger (or synchronization) signal polarity switch to the "+" or "-" position.
　　
　　4. Select the scanning speed
　　
　　According to the approximate value of the measured signal period (or frequency), set the X-axis scanning speed t/div (or scanning range) switch to the appropriate level. In actual use, if it is not necessary to read the measurement time value, the scanning speed t/div fine adjustment (or scanning fine adjustment) knob can be appropriately adjusted to display the waveform of the required number of cycles on the screen. If the edge of the signal needs to be observed, the scanning speed t/div switch should be set to the fastest scanning speed.
　　
　　5. Input the measured signal
　　
　　After the measured signal is attenuated by the probe (or directly input by the coaxial cable without attenuation, but at this time the input impedance is reduced and the input capacitance is increased), it is input into the oscilloscope through the Y-axis input terminal.