What is the use of an oscilloscope?
(1) Obtaining a baseline.
When the operator uses the oscilloscope without instruction manual, the first step is to obtain a thinnest horizontal baseline before the probe can be used for other measurements, the specific methods are as follows: ① Preset the panel switches and knobs.
Pre-set the panel switches and knobs. Brightness is set to moderate, focus and auxiliary focus is set to moderate, vertical input coupling is set to "AC", vertical voltage range selection is set to "5 mv/div", vertical work mode selection is set to "CH1", vertical sensitivity selection is set to "CH1", and vertical sensitivity selection is set to "CH1". The A scan time trimming is set to the calibration position "CAL", the horizontal displacement is set to the middle position, the scanning mode is set to "A", the trigger synchronisation mode is set to "AUTO", the slope switch is set to "+", the vertical channel synchronisation source selection is set to the middle position, the vertical position is set to the middle position, the A and B scan time factors are preset at "0.5 ms/div" together. Set "+", trigger coupling switch "AC", trigger source selection "INT".
② Press the power switch, the power indicator lights up.
③ Adjust the control knob with A brightness focus and other related control knobs, there can be a thin and bright scanning baseline, adjust the baseline so that its position in the middle of the screen and the horizontal coordinate scale basically coincides with the ④ Adjust the trajectory parallelism control.
Adjust the track parallelism control to make the baseline parallel to the horizontal coordinates.
(2) Display signals.
In general, the oscilloscope itself has a 0.5 Vp-p standard square wave signal output port, when the baseline, that is, the probe can be connected to this, at this time there should be a series of square wave signals on the screen, adjusting the voltage range and scanning time factor knob, the amplitude of the square wave and the width of the wave should be varied to this point, indicating that the oscilloscope is basically adjusted and can be put into use.
(3) Measure the signal.
Connect the test line to the CH1 or CH2 input socket, touch the test probe to the test point, you can observe the waveform on the oscilloscope. If the waveform amplitude is too large or too small, you can adjust the voltage range knob; if the waveform period display is not suitable, you can adjust the scanning speed knob.
Special Measurements
(1) AC peak voltage measurement.
①Acquire the baseline.
② Adjust the V/div knob so that the waveform displays 5 div (i.e. 5 frames) in the vertical direction.
③Adjust the "A trigger level" to get a stable display.
④ Calculate the peak voltage with the following formula. Peak voltage = Vertical deflection amplitude × switch pole × probe attenuation multiplier. For example: the upper peak to lower peak deflection is measured to be 5.6 degrees, VOLTS/dir switch is set to 0.5, with × 10 probe attenuation multiplier, the data will be replaced by: Vp-p = 5.6 × 0.5 × 10 = 28 V.
(2) Rise time measurement.
Rise time = horizontal distance (degrees) × time / degrees (blocking pole) / expansion factor.
For example: the distance between the two points of the waveform is 5 degrees, time / degree block level of 1Us, × 10 expansion (the end of the expansion that is × 1), the given value will be substituted: rise time is 5 × 1/10 = 0.5Us.
(3) Phase difference measurement.
Phase difference = horizontal difference (degree) × horizontal scale calibration value (degree/degree).
For example: the horizontal difference value is 0.6 °, each degree calibrated to 45 °, the given value will be substituted into the phase difference formula: 0.6 × 45 = 27 °.
