Velleman projects EDU06 Assembly instructions - Manual (Page 8)

8
Exp.2: Adjustable AC voltage (advantages of the auto-setup function)
Turn RV1 a little further clockwise. The signal goes off-
screen and the Vrms readout displays ?????mV, because
the unit is no longer capable of calculating the correct Vrms.
How can we display the current signal correctly again?
Increase the V/div setting to 0.1V/div. As you will see, the signal fi ts the screen again.
If you turn RV1 clockwise again, the signal will go off screen again.
Changing V/div to 0.2V/div once again restores the display.
You can continue this process until RV1 is turned fully clockwise. In that case, we will measure the
full input voltage, which we also measured in experiment 1.
Is there a better way of measuring unknown voltages?
Yes there is, by using the ‘auto-setup’-function.
Keep pressing any of the arrow keys until V/div and time/div are displayed in reverse
video. The trace immediately adjusts for optimal viewing.
Now you can adjust the voltage from 0 to max. by turning RV1. At any time, the trace
will be displayed correctly and it will not go off-screen. At the lower right-hand corner,
the current Vrms will be correctly displayed.
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