Relevant introduction to the X-axis plug-in part of the oscilloscope
(1) "t/div" scanning speed selection switch and fine-tuning knob. The moving speed of the X-axis light spot is determined by it, and is divided into 21 levels from 0.2μs to 1s. When the switch "fine-tune" the potentiometer is rotated completely clockwise and the switch is connected, it is the "calibration" position. At this time, the indicated value of "t/div" is the actual value of the scanning speed.
(2) "Expand, pull × 10" scanning speed expansion device. It is a push-pull switch. When it is pressed for normal use, the scanning speed of the pulled position increases by 10 times. The indicated value of "t/div" should also be calculated accordingly. Using "Extended Pull × 10" is suitable for observing waveform details.
(3) "→←" X-axis position adjustment knob. It is the horizontal position adjustment potentiometer of the X-axis light trace and is a sleeve-shaft structure. The outer ring knob is a coarse adjustment device. Rotate it clockwise to move the baseline to the right, and rotate it counterclockwise to move the baseline to the left. The small knob placed on the sleeve shaft is a fine adjustment device, suitable for adjusting the expanded signal.
(4) The "external trigger, X external" socket adopts BNC type socket. When using an external trigger, it serves as a socket for connecting external trigger signals. It can also be used as a signal input socket when the X-axis amplifier is externally connected. Its input impedance is approximately 1MΩ. When used externally, the peak value of the input signal should be less than 12V.
(5) "Trigger level" knob Trigger level adjustment potentiometer knob. Used to select the trigger point of the input signal waveform. Specifically, it is to adjust the time to start scanning and decide at which point in the trigger signal waveform the scan is triggered. When turning it clockwise, the trigger point tends to the positive part of the signal waveform; when turning it counterclockwise, the trigger point tends to the negative part of the signal waveform.
(6) "Stability" triggers the stability fine-tuning knob. It is used to change the working state of the scanning circuit, which should generally be in the triggering state. The adjustment method is to set the Y-axis input coupling mode selection (AC-ground-DC) switch to the ground position, set the V/div switch to the highest sensitivity level, and use the level knob to move away from the self-excited state. Turn the stability potentiometer clockwise with a small screwdriver to the end, and the scanning circuit will produce a self-excited scan, and a scanning line will appear on the screen; then slowly turn it counterclockwise until the scanning line just disappears. At this time, the scanning circuit is in the triggering state. In this state, when measuring with an oscilloscope, you only need to adjust the level knob to obtain a stable waveform on the screen, and you can adjust and select the starting point position of the waveform on the screen at will. For a few oscilloscopes, when the stability potentiometer is turned counterclockwise to the bottom, a scanning line appears on the screen; then slowly turn it clockwise until the scanning line disappears on the screen, and the scanning circuit is in a triggering state.
(7) "Internal, external" trigger source selection switch. When placed in the "in" position, the scanning trigger signal is taken from the measured signal of the Y-axis channel; when placed in the "outside" position, the trigger signal is taken from the external trigger signal introduced by the "external trigger X external" input terminal.
(8) "AC", "AC (H)" and "DC" trigger coupling mode switch. "DC" gear is a DC coupling state, suitable for trigger signals that change slowly or have very low frequency (such as less than 100Hz). The "AC" position is the AC coupling state. Since the DC component in the triggering is cut off, the triggering performance is not affected by the DC component. The "AC (H)" file is an AC coupling state with low frequency suppression. When observing high-frequency complex waves containing low-frequency components, the trigger signal is coupled through a high-pass filter, which suppresses low-frequency noise and low-frequency trigger signals (low frequencies below 2 MHz). component) to avoid waveform fluctuations caused by false triggering.
(9) "High frequency, normal, automatic" trigger mode switch. Used to select different triggering methods to adapt to different measured signals and test purposes. "High frequency" gear, select this gear when the frequency is very high (such as higher than 5MHz) and there is not enough amplitude to make the trigger stable. At this time, the scan is in a high-frequency trigger state, and the high-frequency signal (200kHz signal) generated by the oscilloscope itself synchronizes the measured signal. There is no need to adjust the level knob frequently. A stable waveform can be displayed on the screen. It is easy to operate and is conducive to observing high-frequency signal waveforms. "Normal" mode uses the input signal from the Y-axis or external contact source to trigger the scan, which is a commonly used trigger scan method. In "Auto" mode, the scan is in an automatic state (similar to the high-frequency triggering mode), but you can observe a stable waveform without adjusting the level knob. It is easy to operate and is conducive to observing lower frequency signals.
(10) "+, -" triggers the polarity switch. When the "+" position is used, the rising part of the trigger signal is used, and when the "-" position is used, the falling part of the trigger signal is used to trigger the scanning circuit.
