Explanation of Operating Controls of CRO

Operating Controls of CRO

The front panel diagram of a general purpose CRO is shown in the below fig. the panel controls are listed below.

1.       Intensity (Brill): It controls the trace luminance.

2.       Focus: It controls electron beam focus.

3.       Astig: It controls defocussing that occurs due to astigmatism located on the front panel.

4.       Tracerot: Trace rotation about the horizontal axis is possible by this potentiometer.

Pic 1. Front Panel of CRO

5.       Coupling (AC-DC-GND): It decides the mode of input coupling i.e. whether the input to the vertical amplifier is to be AC coupled, DC coupled or GND.

6.       Volts/DIV: It controls vertical deflection co-efficient.

7.       Position: it shifts the display vertically.

8.       Level: This is for selecting the amplitude points on trigger signal at which the time base generator starts the sweep.

9.       +/-: Decides whether the horizontal sweep starts on positive going edge or negative going edge of input signal.

10.    Time/Div: It enables the control in steps of the horizontal time scale when internally generated sweep I fed to the horizontal deflection system of CRT.

11.    Auto/Normal: The auto position is used for frequencies above 50Hz where sweep initiated by the trigger, is applied to horizontal sweep circuit. In normal position sweep is initiated only by the applied trigger. No trace is displayed when there is no adequate trigger signal.

12.    X-Shirt: It shifts the display horizontally.

13.    EXT: in EXT position, the horizontal deflection system is fed from an external source through the concerned channel.

14.    Chop/Alt: it decides whether chop mode or alt mode.