Velleman projects EDU06 Assembly instructions - Manual (Page 11)

11
Experiment 4: Rectifi ed AC, single phase
Connection layout:
Connection summary:
GND clip : 4
Probe tip : 5
Purpose:
The purpose of this experiment is to show what single phase rectifi ed AC looks like on a scope screen.
How?:
Turn on the HPS140 Handheld Pocket Scope 1.
(see HPS140 manual for How-To instructions).
Place the probe switch “x1/x10” to ‘x1’. 2.
Make sure to fl ip SW1 to the correct position 3.
Select 5ms/div and 4V/div.
The display will show a signal similar to this one:
A little theory:
With a single diode, we can convert an AC voltage to a DC voltage. As a diode only conducts the
current in one way, only one half of the waveform can pass. The other half, with inverted polarity, is
blocked. As you can see on the screen, the trace shows ‘interruptions’ where the voltage is 0. This is
the part of the AC voltage that is blocked by the diode. If you move the probe clip from test point 5 and
to test point 1, you remove the diode from the circuit and the display shows the complete waveform
again.
NOTES:
Rectifi ed AC, single phase
S
o a DC voltage As a diode only conducts th
Good to know: Should the rectifi er diode be defective, then you will see either the
complete waveform (if the diode is shorted) or no waveform at all (if the diode is open-
circuit).