User Manual

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Oscilloscope basics
While a multimeter shows an instant voltage level or an average voltage level, an oscilloscope is
capable of displaying voltage levels over a period of time. Voltage is displayed vertically (X-axis)
versus time (Y-axis).
Oscilloscopes can be used to for applications such as:
•Looking at the shape of a signal.
•Measuring the amplitude and frequency of a signal.
•Measuring the time between to events.
•Looking for anomalies such as clipping, noise, distortion,
spikes, ripple, etc…
Analog versus digital:
There are two basic types of oscilloscopes: analog and digital scopes.
Each type has its typical applications, advantages and disadvantages. The advantage of digital
scopes is that they are able to capture and store events for further study. They are also more user
friendly, as they require less setup in order to show a picture of your signal. For our experiments, we
will use a digital scope.
Waveforms:
An oscilloscope will mainly display and measure waveforms. A wave is a pattern that repeats over
time, e.g. the waves of the sea. One cycle or period of a wave is the part of the wave that repeats
itself. When shown on the screen of an oscilloscope, it is called a waveform. There are many differ-
ent waveforms. A couple of them will be used in our experiments:
1. Sine waves: A typical example: The AC power grid
2. Full-wave rectied AC:Theoutputofafullwavedioderectier
3. Half-wave rectied AC:Theoutputofahalf-wavedioderectier
4. DC voltage: Yes, oscilloscopes can also measure DC
5. Sawtooth waveform: In this case: ripple
6. Square wave: The board features a simple two-transistor oscillator which produces a square wave
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analog oscilloscope
Digital oscilloscope
Measuring probe:
To be able to display waveforms, we need to connect the signal to the input of the oscilloscope.
Similar to a multimeter, the oscilloscope uses a measurement lead, but here it is called a ‘probe’.
Connecting the probe:
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Probe tip: The (+) of your probe. It is
needle-shaped to ensure a good electrical
contact with your measuring point.
BNC connector: Connects to the
input of your oscilloscope.
Ground lead with alligator clip:
The (-) of your probe. Connect the alligator
clip to the ground or (-) of the circuit you
wish to examine.
Probe clip: Clips onto the probe tip
and allows you to connect the probe to
the measuring point in a permanent way,
so you have your hands free.
x1/x10 switch:
When set to ‘x1’, the
signal is passed on to the scope without
attenuation. When set to ‘x10’, the signal
is divided by 10, so the signal that is seen
by the scope is ten times smaller than it
acuatally is. This allows you to measure
higher voltages without damaging your
scope.
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Setting up the board:
The board requires a 9VAC (Alter-
nating Current) adaptor (e.g. Velleman
PS905AC (230VAC)). A DC adaptor
instead of an AC adaptor will not damage
the board, but most experiments will not work
correctly. Connect the adaptor at the left hand
side of the board and plug-in the adaptor.
Once powered, the LEDs (LD2 & LD3) should blink
alternately. The board is now ready to perform experiments.
Oscilloscope basics Oscilloscope basics