Teach lesson
Electronics Lab Essentials (6/7): make a waveform readable and stable
Students learn vertical scale, time base, triggering, two-channel comparison, and graticule measurement using real Hive oscilloscope traces.
New to LabsLand? Create your teacher account
Learning Outcomes
Relate vertical scale to voltage and horizontal scale to time.
Estimate peak-to-peak voltage, period, and frequency from a graticule.
Explain trigger source, level, and slope at an introductory level.
Use two channels with a shared reference to compare input and output signals.
Student activity preview
Activity Content
Preview only. In a class session, students can fill in responses and submit their work to the teacher.
1 · A bad trace does not prove a bad circuit
6 min
An oscilloscope turns voltage into a graph: voltage is vertical and time is
horizontal. But a healthy signal can look flat, clipped, off-screen, or unstable
when the display settings are wrong. Before replacing a component, an engineer
asks whether the scope is showing the signal sensibly.
This lesson explains the display controls from first principles, then uses two
real Hive channels to compare a circuit's input and output. No previous
oscilloscope lesson is required.
A laboratory oscilloscope
The controls may look dense, but three questions organize the first setup: How
many volts fit vertically? How much time fits horizontally? What event stabilizes
each sweep?
Optional theory: bench-scope grounds are usually shared
No physical oscilloscope is required; every required observation occurs in
Hive. For a future supervised low-voltage lab using an approved isolated
supply, remember that on an ordinary earth-referenced
bench oscilloscope, channel ground clips are connected together internally and
commonly bonded to protective earth. A bench generator common may also be bonded
to protective earth. With outputs disabled, identify the circuit reference and check
the instrument manuals before connecting grounds. Never clip a scope ground to
mains, an unknown node, or a floating/high-energy circuit unless the laboratory
has approved an appropriately rated isolated/differential measurement method.
A 5 Vpp signal appears almost flat because the vertical range is set to
50 V/div. What should you try before changing the circuit?
2 · Scale the axes and stabilize the sweep
8 min
### Vertical scale: volts per division
If a waveform spans four vertical divisions at 0.5 V/div, then:
Vpp = 4 divisions × 0.5 V/div = 2.0 Vpp.
A smaller V/div value shows a smaller voltage change as a larger movement. If
the value is too small, the trace clips beyond the screen.
### Horizontal scale: seconds per division
If one cycle spans 2.5 horizontal divisions at 2 ms/div, then:
T = 2.5 divisions × 2 ms/div = 5 ms, so f = 1/0.005 s = 200 Hz.
A smaller s/div value zooms into a shorter time interval. It does not change
the real signal frequency.
### Trigger: the repeated starting event
The trigger tells the scope when to begin drawing each sweep. An introductory
edge trigger needs:
- source: which channel to watch;
- level: the voltage crossing used as the event;
- slope: rising or falling crossing.
For a stable sine wave on channel 1, a channel-1 trigger near the waveform's
center with a rising slope is a sensible start. The trigger level is a scope
condition; it is not a voltage delivered to the circuit.
Three control groups
Scale makes the trace readable. Triggering makes repeated cycles appear in a
consistent horizontal position.
Each channel also has a 0 V reference marker. Identify that marker before
interpreting DC offset or polarity. Vpp is still measured from the waveform's
minimum to maximum; the trace does not need to be centered on 0 V to measure
peak-to-peak height correctly.
A cycle spans 4 divisions at 0.5 ms/div. Calculate the period in seconds and
then the frequency.
The waveform is visible and correctly sized but drifts sideways between sweeps.
Which control group is most relevant?
3 · Compare two real channels
10 min
The prepared circuit applies a sine wave to an RC low-pass network. Channel 1 shows
the input; channel 2 shows the output. Both channels use the same circuit ground.
This circuit configuration uses approximately 1 kΩ and 1 µF. At 160 Hz,
an ideal first-order model predicts an output/input magnitude near 0.705.
That is a circuit-specific comparison, not a universal RC ratio. Real
readings and visual estimates vary.
The Hive scope is configured for DC coupling, 1× attenuation, a channel-1
rising-edge trigger near 0 V, and an automatic trigger mode. If one of those
controls is not available in your interface, write not available to inspect
and record the setting shown or provided.
Make both RC waveforms readable
Open Hive and wait for the saved RC circuit.
Open the Function Generator and confirm a sine wave near
160 Hz, approximately5 Vpp, and0 Voffset. Do not change it.Open the Oscilloscope and keep channels 1 and 2 visible.
Identify each channel's
0 Vmarker, displayed vertical scale, and coupling; then identify the horizontal time-per-division setting.Use channel 1 as the trigger source with a level near the waveform center and a rising slope, or retain the equivalent stable saved trigger. Note the trigger mode.
Select Perform Measurement (
Realizar medición) once.If either trace is clipped or tiny, adjust that channel's vertical scale. If too few or too many cycles are visible, adjust the horizontal time scale. Repeat the measurement after a setting change.
Estimate each channel's
Vppfrom minimum-to-maximum divisions × volts/div, and estimate the period from divisions × time/div. Record the settings used with the values.
Complete exactly two rows, one per channel. If the scope provides an automatic
measurement, you may use it, but still record the display scale. Format-only
example: `CH1 — input | 1 V/div | 5 divisions | 5 Vpp | 2 ms/div |
3.125 divisions | 6.25 ms`. This means
5 divisions × 1 V/div = 5 Vpp and 3.125 divisions × 2 ms/div = 6.25 ms.
Replace every value with what you observe. Leave extra blank rows unused.
Two-channel oscilloscope record
Complete one row for channel 1 input and one for channel 2 output. Record the scale settings used, counted divisions, calculated Vpp, and period.
| Channel and signal | Vertical scale V/div | Peak-to-peak height divisions | Calculated Vpp V | Horizontal scale ms/div | One-cycle width divisions | Calculated period ms |
|---|---|---|---|---|---|---|
Record the setup information shared by your two Hive traces: coupling, probe or
channel attenuation, where 0 V is marked, and trigger source, slope, level,
and mode. For any control you cannot inspect in the Hive interface, write
not available to inspect and record the setting shown or provided.
Calculate CH2 Vpp ÷ CH1 Vpp. Enter the ratio without a unit, then explain what
it says about the output compared with the input. Use your two table values.
Compare channels 1 and 2. State what stayed approximately the same and what
changed, using at least one period and both Vpp values.
4 · Optional theory: diagnose a physical scope display
6 min
No physical scope or probe is required. For a future supervised lab, use
this order:
1. With sources disabled, identify the approved shared circuit reference. Confirm in the manuals whether the scope grounds and generator common are earth-bonded; then connect every probe ground only to that reference.
2. Use DC coupling when you need both AC variation and DC offset. AC coupling intentionally removes the steady component from the display.
3. For ordinary low-voltage lab signals, a 10× probe is a common starting choice because it loads the circuit less; match the probe switch and channel setting. A 10× probe does not make a hazardous voltage safe. Use 1× only when its loading, bandwidth, and voltage rating are suitable, and never exceed probe/scope ratings.
4. Choose a vertical scale that fits the signal without making it tiny.
5. Choose a time scale that shows a few cycles.
6. Trigger from the channel and edge you want to stabilize.
7. Record probe factor, coupling, scales, trigger, and measured value.
Match each symptom to a sensible first display check. Select all correct pairs.
Using the Hive evidence and the theory above, write one compact oscilloscope
setup record that another student could reproduce later for your channel-1
trace.