OSCILLOSCOPE

Oscilloscope is used for the several purposes:

• Its primary use is to see the waveform of the signals on the screen.
  
• It can be used to determine the frequency of the signal.
  
• It can be used to compare two signals.
  
• It can be used to see the AC component of the signal separately
  
• It can be used for the measurement of the signal amplitude.
  
• It can be used for the adjustment of the timing of the signals.
  

   

  1 – Channel input
  

  The oscilloscopes available in college lab have two input channels. Channel 1 and 2.
  

  2
  

  –

  Volts/Division
  

  This tab is used to adjust the scaling for the amplitude of the signal. The tab selects the volts/division for the signal display. If the tab is set at 2V/div it means that each vertical division equals 2 V.
  

  3 – Time/Division
  

  This tab adjusts the scaling in the horizontal axis. If the tab is set to 1 ms/ div it means that each division corresponds to 1ms of time unit.
  

  4 – Slide Switch: This switch can be used to visualize the AC and DC components of the signal.
  

  At top is the AC mode. In this mode the signal input is passed through a capacitor in series which blocks the DC shift of the signal and only the AC component is visible.
  

  In the middle is the GND, when the switch is in this position the there will be no signal on screen except for a dead line at the centre (if the centre line is calibrated at the centre otherwise it is shifted accordingly.
  

  At the bottom position, the signal is displayed as such with full DC and AC components.
  

  5 – Vertical Position
  

  This tab adjusts the vertical position of the centre. It must be calibrated such that the centre line (dead line) is at the exact centre if slide switch is set to GND. ADD will add both the signals.
  

  6 –
  

  7 – Horizontal Position
  

  This tab adjusts the horizontal position of the origin. This tab is usually used to shift the signal right or left during measurements.
  

  8 –
  

  9 – Power button
  

  10 – Magnification
  

  11 – Intensity For adjusting the intensity of the display signal
  

  12 – Illumination Used to adjust the illumination of screen (back light).
  

  13 – Focus This will adjust the focus of the display signal. Adjust it for best focus.
  

  14 – Channel Select
  

  CH1 and CH2 will select channel 1 or 2 individually. ALT will display both channels simultaneously. CHOP will display each channel individually at alternate triggering cycles.
  

  15 – Channel invert This button if pushed will invert the signal on the channel 2 of oscilloscope.
  

  16 – Trigger Mode Under normal conditions set this to top most position.
  

   

  17 – Trigger Source For normal operation set this to the internal trigger source/
  

  18 – Trigger Level Set this to middle value for normal trigger postiion
  

  19 – Slope
  

  20 – Calibration Signal
  

  The Probe is placed here to calibrate the Oscilloscope. The signal available here is 1 kHz 1 V peak to peak. The Volts/div and the time/div scales are adjusted so that the signal appears in the corresponding divisions. The rest adjustments are made to make sure the oscilloscope is working and calibrated.
  

  21- GND
  

   

  See the animation at: http://hyperphysics.phy-astr.gsu.edu/Hbase/electronic/scope.html#c1
  

Procedure for calibration of OSCILLOSCOPE

First the calibration probe is inserted in the calibration pin just below the button 10 and the earth part of the probe is inserted in port 21 which is the ground. The default specifications of the output from this probe are 1 KHz and 1 V peak-to-peak. The slide switch (4) is pointed to GND and then the dead line is calibrated such that it is in the centre of the screen by using the Vertical and Horizontal Position Buttons the time/division (button 3)
is
set to 1 ms/division. The volt/division scale (button 2) is selected appropriately.

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