Of all the tools that engineers may reach for, oscilloscopes are among the most powerful and relevant. This can be particularly the case in the event of something going wrong with an electrical circuit.
After all, when an electrical or electronic system stops performing in line with expectations, a professional engineer will rarely begin with simply replacing components at random. Instead, they will typically investigate the problem.
In this regard, the ability that an oscilloscope gives them to see electrical signals in real time can be invaluable for determining where faults originate. It is an instrument that in effect, is able to turn hours of head-scratching into minutes of clear insight.
An Introduction to Oscilloscopes
Sometimes referred to as simply a “scope”, an oscilloscope is a test instrument that displays electrical signals as waveforms. This sophisticated voltmeter enables engineers to easily observe how voltage changes over time.
Users of oscilloscopes aren’t simply presented with a single number indicating the voltage value at one moment in time. Instead, this tool draws a graph (a waveform) on a screen, with the vertical axis displaying voltage, and the horizontal axis showing time.
This visual representation helps engineers detect abnormalities that might have remained hidden if they were instead dependent on a standard multimeter.
4 Steps in The Use of Oscilloscopes for Fault Diagnosis
Oscilloscopes can be indispensable due to how they enable engineers to observe behaviour as it happens. This helps them achieve various typical diagnostic goals, such as identifying intermittent faults, detecting electrical noise or interference, checking signal integrity, and comparing actual performance against expected behaviour.
Engineers tend to take the following steps in their use of oscilloscopes:
- Step 1: Establish A Baseline
The first stage of the fault diagnosis process is normally establishing an understanding of what “normal” operation looks like.
Engineers do this by comparing measurements against manufacturer specifications, capturing waveforms from a functioning unit, or referring to historical records from previous inspections.
A known-good waveform then becomes the benchmark.
- Step 2: Probe Strategic Test Points
Oscilloscopes work through probes connected to specific points in a circuit.
Although oscilloscopes often monitor only selected channels at a time, engineers target test points most likely to reveal the source of the issue. Examples of these include the likes of power supply rails, input and output stages, clock signals, and sensor interfaces.
- Step 3: Analyse Waveform Shape
Analysis of a waveform often reveals the nature of a fault prior to components being removed.
In scrutinising the waveform, engineers typically look for such characteristics as distortion, noise, timing errors, and/or amplitude problems.
For instance, if there are unexpected changes in the waveform shape, this might indicate component damage, saturated amplifiers, or incorrect loading.
- Step 4: Use Triggering to Capture Intermittent Faults
An especially valuable function of an oscilloscope is triggering. This allows the instrument to wait until a specific event occurs before it captures data.
Examples of such an event can include a voltage exceeding a threshold, a pulse becoming too narrow, a communication packet failing, or a startup transient appearing.
Triggering can be a particularly useful feature for the diagnosis of faults that occur only occasionally.
Conclusion: Oscilloscopes Are Still a Must-Have for Engineers
Much has changed in the world of electrical and electronic systems over recent years, including the emergence of ever more complex circuits.
However, one thing that hasn’t greatly altered is the fundamental usefulness of an oscilloscope. This tool is more than an instrument for voltage measurement; it enables engineers to visualise timing, signal quality, and transient behaviour.
For seasoned chartered engineers, apprentices learning their trade, and all manner of professionals in-between, oscilloscopes can play a central role in their efforts to pick out faults and understand how systems behave under real operating conditions.
