Teach lesson
Electronics Lab Essentials (5/7): create a controlled test signal
Students learn waveform, frequency, period, peak-to-peak amplitude, offset, and reference by configuring and observing a real Hive function-generator signal.
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Learning Outcomes
Identify sine, square, and triangle waveforms.
Define frequency, period, peak-to-peak voltage, amplitude, and DC offset.
Convert between frequency and period using f = 1/T.
Change one generator setting at a time and verify the result with an oscilloscope.
Student activity preview
Activity Content
Preview only. In a class session, students can fill in responses and submit their work to the teacher.
1 · Give a circuit a known challenge
6 min
A DC supply lets you observe a circuit at one steady voltage. A function generator lets you investigate how the circuit responds as frequency and waveform change: “What happens when voltage rises and falls 160 times per second? What if the shape is smooth, abrupt, or triangular?”
A function generator produces a controlled voltage waveform. Engineers use it as a known input while observing a circuit's output. A useful generator setting is not just “on”: it includes waveform, frequency, amplitude, offset, and reference. In this lesson, the connected oscilloscope acts as the viewing instrument; all oscilloscope steps needed here are provided.
A laboratory function generator
Physical generators vary, but their core settings describe the same signal. Confirm the output is disabled while making uncertain connections, and begin with a modest amplitude appropriate for the circuit.
Optional theory: generator common and protective earth
No physical generator or oscilloscope is required; every required action occurs in Hive. For a future supervised low-voltage lab using an approved isolated supply, remember that on many bench generators the output connector's outer conductor is bonded to protective earth; ordinary oscilloscope ground clips may be earth-bonded too. They are not independent floating references. With outputs disabled, identify the circuit reference and verify the instrument grounding in the manuals before connecting commons. Never attach a generator common or scope ground clip to mains, an unknown node, or a floating/high-energy circuit unless the laboratory has approved an appropriately rated isolated/differential method.
Three common output shapes
A sine wave changes smoothly, a square wave changes abruptly between levels, and a triangle wave rises and falls at an approximately constant rate.
Which labeled waveform has abrupt transitions and spends most of each cycle at one of two voltage levels?
2 · Specify the signal completely
8 min
Use these quantities:
- Frequency
f(Hz): cycles per second.160 Hzmeans 160 complete cycles each second. - Period
T(s): time for one complete cycle. Frequency and period are reciprocals:f = 1/TandT = 1/f. - Peak-to-peak voltage
Vpp: difference from the waveform's minimum to its maximum. - Amplitude: often the distance from the center value to one peak. For a symmetric waveform, amplitude is half of
Vpp. Instrument conventions vary, so read the displayed unit—Hive labels the relevant setting inVpp. - DC offset: the center value around which the waveform moves. A
0 Voffset centers a symmetric signal around ground. - Reference/ground: the node against which the signal voltage is defined.
- Load convention and source impedance: many laboratory generators have a
50 Ωsource and can display amplitude for either a50 Ωload or a high- impedance load. The same displayed setting may produce a different voltage at the circuit if the load convention is wrong. Record the selected convention and verify the actual-load Vpp with an oscilloscope.
Read a periodic waveform
Changing frequency compresses or stretches the waveform horizontally. Changing Vpp scales it vertically. Changing offset moves its center up or down.
Calculate the period of a 160 Hz signal. Show T = 1/f, first in seconds and then in milliseconds.
A symmetric waveform is centered at 0 V and set to 5 Vpp. What ideal maximum and minimum should it reach?
3 · Change one setting and verify it
10 min
The saved Hive circuit connects the generator to an RC network and connects two oscilloscope channels. In this lesson, use channel 1 as the generator-input evidence. The RC behavior is not being assessed yet.
Run 1 uses the saved settings: sine, 160 Hz, approximately 5 Vpp, and 0 V offset. Run 2 changes only frequency to 80 Hz. If amplitude, offset, or waveform changes accidentally, restore the Run 1 values before continuing.
Create and inspect two test signals
Open Hive from this block and wait for the saved RC circuit.
Open the Function Generator. Record the saved waveform, frequency,
Vpp, and offset before changing anything.Open the Oscilloscope. Keep channel 1 visible and use the saved display settings for the first run.
Select Perform Measurement (
Realizar medición) once. Observe channel 1 and estimate the period from the trace or available measurements.Return to the function generator and change only the frequency from
160 Hzto80 Hz. In Hive, press Freq, Enter Number, Offset (the key also labelled8), Recall (the key also labelled0), and then the right-arrow unit key labelled Hz. Keep sine,5 Vpp, and0 Voffset.Select Perform Measurement again. Observe channel 1 and estimate the new period.
If the waveform becomes difficult to see, adjust only the oscilloscope time scale; do not change generator amplitude to fix a horizontal display problem.
Confirm the 80 Hz entry before measuring
After the key sequence, pause and confirm that the generator display reads 80 Hz before selecting Perform Measurement. If it does not, restore the saved setup, reopen Function Generator, and repeat the frequency entry without changing waveform, Vpp, or offset.
Complete exactly two rows. Observed period may be an estimate from the trace; use milliseconds. Format-only example for the saved row: Saved signal | sine | 160 Hz | 5 Vpp | 0 V | 6.25 ms. The numeric cells accept the number while the heading supplies the unit. Use your observed values rather than copying the example. Leave extra blank rows unused.
Function-generator settings and evidence
Complete two rows: saved 160 Hz run and changed 80 Hz run. Record generator settings and the period observed on oscilloscope channel 1.
| Run | Waveform | Frequency Hz | Amplitude setting Vpp | DC offset V | Observed period ms |
|---|---|---|---|---|---|
Explain what changed and what stayed constant. Use both frequencies and periods, then state whether your evidence supports T = 1/f.
4 · Optional theory: reproduce the signal later
6 min
No physical generator is required. Use this theory when preparing for a future supervised lab:
- Confirm the circuit's permitted input range and reference.
- Disable the output while making uncertain connections.
- Choose waveform, frequency,
Vppor amplitude convention, offset, and the correctHigh-Z/50 Ωload convention. - With power off, identify whether the generator common and scope ground are earth-bonded; connect them only to the approved shared reference.
- Enable the output and verify the actual-load Vpp and offset with an oscilloscope.
- Change one setting at a time and record it.
Which details would be needed to reproduce the saved Hive signal on another function generator? Select all that apply.
Write the saved signal as one compact, reproducible generator specification.
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