10-06-2017, 06:52 AM
RUBY CHAUDHARY
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INTRODUCTION
Invented by German scientist Karl Ferndinand Braun in 1897.
He introduced CRT with Fluorescent screen and named it as CRO.
Consist of Cathode Ray Tube(CRT)
CRTs operates well in voltage range of 2-5 kv
Popular instrument to show time, voltage both DC and AC. Shows Volts / Time.
Display waveforms.
Opetares on Voltages.
Very fast X-Y Plotter
Movement of luminous spot in response to Input Voltage traces waveform w.r.t Time .
Cathode Ray Oscilloscope
Cathode (-ve ) is heated, emits electrons, accelerated toward a (+ve) fluorescent screen
Horizontal deflection plates.
Vertical deflection plates
Phosphor screen(Fluorescent screen)
All are enclosed in Glass envelope.
Cathode Ray Tube(CRT)
When electrons hit the screen the phosphor is excited and emits light.
Persistence. How long the display glows.
Connect a signal to Vertical deflection plate.
At same time a voltage that increases linearly with time (Ramp) is applied to the Horizontal deflection plates.
This horizontal linear deflection is produced by the Sweep generator.
Sawtooth wave.
When the sweep signal returns to zero ie the end of the sweep, the beam flies back to the start position. The beam is cut off during the flyback time.
The display is made to appear stationary.
This controlled by your adjustment settings.
The eye sees a waveform.
X is <--> Horizontal
Y is ^ Vertical Height of trace
The signal is amplified by the vertical amplifier, applied to the vertical plates.
A portion of the vertical amplifier signal is applied to the Sweep Trigger.
The sweep trigger generates a pulse
This pulse turns on the sweep generator initiating the sawtooth wave form.
The sawtooth wave is amplified by the horizontal amp and applied to the horizontal deflection plates
The trigger can be based on 50 (60) Hz