The Oscilloscope

First Looks : Controls & Indicators


Please click on the various parts of the Oscilloscope for a description of the part.


1. CH1 Position Control

Rotation of this knob will adjust the vertical position of the Channel 1 waveform on the screen. In the X-Y operation, rotation adjusts vertical position of display.

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2. CH1 Volts/Div Control & Variable Control

For the Volts/Div Control, it is a vertical attenuator for channel 1. Provides step adjustment of verticaal sensitivity in 1-2-5 sequence. VARIABLE control is turned to the CAL position, the calibrated vertical sensitivity is obtained. In X-Y operation, this control serves as the attenuator for Y-axis.

Rotation of the variable control provides fine control of channel 1 vertical sensitivity. In the fully clockwise (CAL) position, the vertical attenuator is calibrated. In X-Y operation, this control serves as the Y-axis attenuation fine adjustment.

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3. CH1 AC-GND-DC Switch

This switch is the Channel 1 vertical axis coupling mode selector, for X-Y operation, the Y-Axis coupling mode control.

 AC: AC Input coupling with blocking of any DC signal component.
 GND: Vertical amplifier is disconnected from the input signal and connected to ground. This mode is useful in determining the zero reference.
 DC: DC Coupling, with both the DC and AC components of the input signal displayed on the CRT.

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4. CH1 INPUT Jack

Vertical input for channel 1 trace in normal sweep operation. Y-axis input for X-Y operation.

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5. CH2 Position / PULL INVert Control

CH2 Position:
Rotation adjusts vertical position of channel 2 trace.

INV:
Push-pull swtich selects channel 2 signal inverted when pulled out.

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6. CH2 Volts/Div Control & Variable Control

Volts/Div Knob:
For the Volts/Div Control, it is a vertical attenuator for channel 1. Provides step adjustment of verticaal sensitivity in 1-2-5 sequence. VARIABLE control is turned to the CAL position, the calibrated vertical sensitivity is obtained. In X-Y operation, this control serves as the attenuator for X-axis.

Variable Control:
Rotation of the variable control provides fine control of channel 1 vertical sensitivity. In the fully clockwise (CAL) position, the vertical attenuator is calibrated. In X-Y operation, this control serves as the X-axis attenuation fine adjustment.

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7. CH2 AC-GND-DC Switch

 

Three position lever switch which operates as follows :

 AC: Blocks DC Component of channel 2 input signal.
 GND: Opens singnal path and grounds input to vertical amplifier. This provides a zero-signal base line, the position of which can be used as a reference when performing DC measurements.
 DC:  Direct input of AC and DC component of channel 2 input signal.

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8. CH2 INPUT Jack

Vertical input for channel 2 trace in normal sweep operation. X-axis input in X-Y operation.

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9. MODE Switch

Selects the basic operating mode of the oscilloscope.

CH1:
Only the input signal to channel 1 is displayed as a single trace.

CH2:
Only the input signal to channel 2 is displayed as a single trace.

ALT:
Alternate sweep is selected regardless of sweep time.

CHOP:
Chop sweep is selected regardless of sweep time at approximately 300 KHz.

ADD:

The waveforms from channel 1 and channel 2 inputs are added and the sum is displayed as a single trace. When the CH2 INV Button is engaged, the waveform from channel 2 is subtracted from the channel 1 waveform and the difference is displayed as a single trace.

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10. GND Terminal

Earth and chassis ground reference.

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11. CAL Terminal

Provides 1 kHz, 1 V peak-to-peak square wave signal. This is useful for probe compensation adjustment.

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12. EXT Trigger Input Jack

Input terminal for external sync signal.
When SOURCE switch is selected in EXT position, the input signal at the EXT TRIG input jack becomes the trigger.

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13. Power Switch

A press of this switch turns the power ON.

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14. Power Indicator

Lights when the POWER swtich is pressed.

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15. Intensity (REAL) Control

Controller for adjusting the brightnesss of the real-time waveform.

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16. Focus / PULL Astig Control

FOCUS: Focus adjustment

ASTIG: Used to bring the waveform into the best condition with the FOCUS adjustment by adjusting trace and spot aberration. Pull the knob to make a spot circular.

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17. Scale Illum / PULL Trace Rota Control

SCALE ILLUM:
Brightness adjustment of the scale of the CRT. For photographing, rotate the knob to adjust bright to prevent halation caused by too bright illumination.

TRACE ROTA:
Tilt adjustment of the horizontal bright line in the case where goemagnetism influences the bright line to tilt.

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18. Variable SWEEP TIME/DIV Control

A SWEEP Time / Div Control

Range select dial of 19 ranges from 0.2us/div to 0.5s/div.
To calibrate the set value, rotate the SWEEP VARIABLE controlle clockwise up to the CAL position.

B SWEEP Time / Div Control

Range select dial of 17 ranges from 50ms/div to 0.2us/div. Set this dial to a value same as the A SWEEP Time/Div Control or higher than it.

A SWEEP Variable Control

Fine sweep time adjustment. In the fully clockwise (CAL) position, the sweep time is calibrated.

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19. Horizontal Position / PULL 10X Magnification Control

Horizontal position controller, which provides horizontalal shift of waveform. By pulling the knob, the sweep time is quickened ten times.
In the X-Y operation, rotation adjusts horizontal posistion of display.

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20. Level / PULL Slope (-) Control

LEVEL:
Trigger level adjustment determines point on triggering waveform where A sweep triggered.

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21. Hold Off Control

HOLD OFF:
Adjusts holdoff (trigger inhibit period beyond sweep duration). Clockwise rotation from the NORM position increases holdoff time, up to 10 times at the MAX position (fully clockwise).

Trace Seperation Control

Adjusts vertical seperation between A sweep and B sweep (control has effect only in the ALT of HORIZ. MODE).

Clockwise rotation increases seperation; B sweep moves down with respect to A sweep up to 4 divisions.

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22. Coupling Switch

Selects coupling for sync trigger signal.

AC:
Trigger is AC coupled. Blocks DC component of input signal; mostly commonly used position.

HFrej:
Sync signal is DC coupled through a low-pass filter to eliminate high frequency components for stable triggering of low frequency signals.

DC:
The sync signal is DC coupled for sync which includes the effect of DC components.

TV FRAME:
Vertical sync pulses of a composite video signal are selectec for triggering.

TV LINE:
Horizontal sync pulses of a composite video signal are selected for triggering.

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23. Source Switch

Sweep trigger source select switch.

VERT MODE:
The sweep trigger source is selected with the MODE selector for the vertical operation. When the vertical MODE selectoris set to CH1, the channel-1 signal is used as a trigger source. When is is ser to CH2, the channel 2 signal is used as a trigger source. When ser to ALT both the channel 1 and channel 2 signals are used alternatively. When set to CHOP or ADD, the channel 1 signal is used as a trigger source.

CH1:
Channel 1 signal is used as a trigger source.

CH2:
Channel 2 signal is used as a trigger source.

LINE:
Sweep is triggered by line voltage.

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24. Triggering Mode Control

Selects triggering mode.

AUTO:
Triggered sweep operation when trigger signal is present, automatically generates sweep in absence of trigger signal.

NORM:
Normal triggered sweep operation. No trace is presented when a proper trigger signal is not applied.

X-Y:
X-Y operation. Channel 1 input signal produces vertical deflection (Y-axis). Channel 2 input signal produces horizontal deflection (X-axis).
This operates regardless vertical MODE selection.

SINGLE:
Single sweep mode

RESET:
Reset mode of single sweep operation. when reset, the switch returns to the SINGLE position, with the READY LED lighting until completion of the sweep.

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Ready Indicator

When the reset is single-sweep operation, this lamp lights and remains lit until the sweep operation is completed.

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Horizontal Mode Switch

Used to select the horizontal display mode.

A:
Only A sweep is operative, with the B sweep dormant.

ALT:
A sweep alternates with the B sweep. For this mode of operation, the B sweep appears as an intensified section of the A sweep.

B:
Only delayed B sweep is operative.

X-Y:
Channel 1 becomes the Y-axis and channel 2 becomes the X-axis for the X-Y operation. The setting of the vertical MODE and TRIG MODE switches have no effect.

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Delay Time Postion Control

Used to set delay time of the B sweep start point from the A sweep start point, if the HORIZ MODE selector is set to ALT or B position. (Delay time position) It controls delay time continuously between 0,2 and 10 times of a set value with the A sweep time/div controller.

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CRT Screen

This is where all the output signals will be displayed.

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Oscilloscope Training Package Programmed by Jigar C. Shah NTU Final Year Project.

Copyright © 1997-8 Jigar C Shah