Changing the Vertical Signal Gain
- When a signal is viewed on the CRO display the
amplitude of the signal can be measured by counting the
number of divisions that the signal "covers" on
and multiplying by the scale of each division.
- i.e if the signal
"covers" 4 divisions at 5 volts
the signal amplitude is 20 volts.
- Now because the signal being viewed can be a
large range of sizes ( from a couple of millivolts up to
200 Volts ) we need to adjust the viewing scale on the
display in order to achieve the optimum viewing size of
- i.e if we attempted to view a
10mV sine wave and a 30V sine wave on the
same scale one or both of the signals
would not be properly visible on the
A graphical example of
How Do We Change The Vertical
- Well firstly
we consider the diagram below which shows the Vertical
Gain Control for each channel
labelled with Volts/div.
- Now we know that each control has settings
labelled from 5
millivolts per division to 20 Volts per
- The vertical
gain is changed by simply rotating the control to the
desired setting. Some graphical examples of this.
Things To Remember About The
Vertical Gain Control.
- If we are viewing two signals on the display,
they can be viewed such that each signal is on a
different vertical scale. So be aware of the setting of
both vertical gain controls.
- The red knob ( the Variable
Vertical Gain Control ) that lies
within the Vertical Gain Control
must be rotated completely clockwise until a
"click" is heard to ensure calibration and
correct readings. (Be Warned -
there will be turkeys who play around with these knobs
just to ruin your results and get a laugh, so always be
sure to check this. )
Variable Vertical Gain Control
- This control as mentioned above is located in the
centre of the Vertical
Gain Control and is used to vary the
signal gain ouside the limits of the Vertical Gain
Control. It is most useful to check the general shape of
- ALWAYS be sure that this
control is not left in the uncalibrated ( calibration
relies on the knob being rotated completely clockwise
until a "click" is heard ) position when making
measurements of signal amplitude.
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Revised: Friday, 17 July 1998