Basic principle and measuring method of oscilloscope
Oscilloscope is one kind of electrical measurement equipment with wide application. It could transfer invisible electrical signal to visible image to facilitate people research change processes of all kinds of electricity phenomenon. Oscilloscope use narrow electron beam which consists high-speed electronics and project onto screen coated with fluorescent substance to produce small spot (this is original working principle of analog oscilloscopes. Under the function of measured signal, electronics like the point of a pen which could on screen describe change curve of measured signal during instantaneous value. An oscilloscope can be used to observe the waveform curves of various signal amplitudes varying with time. It could also be used to measure various electricity, such as voltage, current, frequency, phase, amplitude modulation and etc.
(1) pre-adjusting: counterclockwise rotate the brightness button to the bottom, shift vertical and horizontal positions to the middle, set the attenuation gear at the highest level, place scan “outside X gear”
(2) turn on the power, do following steps waiting for one or two minutes after the indicator light is on
(3) adjust luminance first, then adjust the focus, adjust vertical and horizontal displacement to make the light point in center of suitable area.
(4) adjust scan, scan fine tuning and X gain, observe scan.
(5) adjust outside X gear to suitable scan range, observe the voltage waveform according to sine and cosines law on vertical direction inside the device.
(6) Connect the applied voltage to be studied to oscilloscope through Y input and earth. Adjust all gears to suitable position and observe waveform (the picture changes with time) (the synchronous polarity switch can make the starting point of the image start from positive half cycle or negative half cycle.)
(7) If you want to observe the vertical migration of light spot (with one added DC voltage), could adjust scan to “outside X gear”.
In general, the frequency of the calibration signal is 1kHz and the amplitude is 0.5v, which is used to calibrate the internal scanning oscillator frequency of the oscilloscope. If it is abnormal, the corresponding potentiometer of the oscilloscope (internal) should be adjusted until it is consistent.
Are the different oscilloscope probes interchangeable?
It's interchangeable as long as it's the same interface
Note, however, that the matching capacitance of the probe matches that of the oscilloscope
So maybe it needs to be adjusted
The other is impedance matching of the probe.The impedance matching part of the probe should be adjusted prior to use.Usually there is an adjustable capacitance at one end of the probe near the oscilloscope, and some probes are near
The probe also has an adjustable capacitance at one end.They are used to adjust the impedance matching of the oscilloscope probe.If the impedance does not match, the measured waveform will be distorted. The method of adjusting the impedance matching of oscilloscope probe is as follows: firstly, the input selection of oscilloscope is played on GND, and then the Y-axis displacement knob is adjusted to make the scan line appear in the middle of the oscilloscope. Check if the scan line is horizontal (i.e., if it coincides with the horizontal center line of the oscilloscope), if not, adjust the horizontal balance knob (usually the analog oscilloscope has this adjustment terminal, in the hole, need to use a screwdriver into the adjustment.Digital oscilloscope need not be adjusted).
Then, the input selection of the oscilloscope is connected to the dc coupling, and the oscilloscope probe is connected to the test signal output end of the oscilloscope (generally, the oscilloscope has this output terminal, usually the square wave signal of 1KHz), and then the scanning time knob is adjusted to make the waveform display for about 2 cycles. Adjust the Y-axis gain knob so that the peak - peak of the waveform is about 1/2 screen width.Then look at the top and bottom sides of the square wave to see if they are horizontal.If the phenomenon of overshoot and tilt occurs, it means that the matching capacitance on the probe needs to be adjusted.Adjust it with a small screwdriver until the waveform on both sides is level and there is no overshot.Of course, due to the quality of the oscilloscope probe, may not be adjusted completely without distortion effect, then can only be adjusted to the best effect.
Advantages and disadvantages of using digital oscilloscope