Use of oscilloscope

Use of oscilloscope

summary ：

The main purpose of the oscilloscope is to draw the electrical signals that change with time in a graphical way , Most oscilloscopes use time x Axis , Voltage is y The two-dimensional figure produced by the axis .

One 、 Reading of panel voltage value

The waveform voltage value can be read according to the number of grids and the resolution

Two 、 Oscilloscope function and usage

1. Purpose of oscilloscope

The control buttons around the oscilloscope screen can adjust the display proportion of the graph , The horizontal and vertical scales of the display can be adjusted , In this way, you can zoom and view the signal in the two dimensions of time and amplitude , And it can be adjusted “ Trigger ” Knob for , help “ Stable ” Waveform display .

In addition to these basic functions , The oscilloscope can also help engineers quickly quantify the frequency of the measured signal 、 Amplitude and other waveform parameters . In a word, oscilloscope can test parameters based on time and voltage , as follows ：

Time based parameters : Frequency and period 、 Duty cycle 、 Rise time and fall time

Voltage parameters : Range 、 Maximum voltage 、 Minimum voltage 、 Average voltage, etc

2. Oscilloscope application scenario

（1） In debugging the input of the circuit 、 It is used to determine the frequency and amplitude of the signal when outputting and intermediate system , Based on this information, we can judge whether the circuit works normally .

（2） Determine the noise level in the circuit

（3） Judge the shape of the waveform – Sine wave 、 square wave 、 Triangle wave 、 Sawtooth wave 、 Composite waveform, etc

（4） Measure the phase difference of two different signals

3. Oscilloscope testing skills

Once the probe is calibrated , You can measure the signal on the circuit , A few tips when measuring ：

1 Easy to use 、 Security 、 Connection mode that does not affect performance – Connect the grounding clip of the probe to this point . Sometimes you need to weld a very thin wire on the circuit board to facilitate the probe's grounding clamp , The tip end of the probe can also pass through the clip with spring 、 Hooks, etc. can easily connect the signal points to be tested - In short, we need to find a way , You don't have to hold the probe in your hand all the time .

2. Avoid noise caused by improper measurement methods - If the signal to be measured is high frequency （ Dozens of MHz） The signal , When testing with an oscilloscope, the connection of the ground wire should be as short as possible , Otherwise, the antenna will be formed due to the loop formed by the probe's ground wire and the probe's tip , The high-frequency signal near the point to be measured （ Space radio waves 、 Switch signal radiation on the board ） Received and superimposed on the signal to be tested , It will bring great interference to your debugging . In most cases, the coaxial line needs to be directly welded to the circuit board , Avoid generating receiving circuits .

3. Be familiar with all the measuring tools of the instrument you use - Different oscilloscopes have different measurement functions , You can check the instructions and adjust the buttons. First, get familiar with the functions of the instrument you use , For example, cycle 、 Peak to peak 、 Pulse width 、 Duty cycle 、 Rising edge 、 Falling edge 、 Measurement of average voltage and how to use FFT function , What can be measured and displayed automatically .