Electronics concepts are some of the hardest to visualise, even in the laboratory; it is hard to see the electrons as they whizz through the wires and even more difficult to "see" the electromotive force! Tools like oscilloscopes and network analysers allow powerful visualisation of electronic effects, but using them proficiently has a steep learning curve.
Electronic engineers have long embraced simulation as a design tool. However, it is generally taught as a complementary skill to laboratory training, rather than to actually teach practical experimentation. While access to teaching laboratory spaces is limited, simulation tools can be not only a professional skill, but a valuable method of teaching students to be good experimentalists and designers. Simulations can let us visualise normally unseen effects, and probe circuits in unnatural places, all in complete safety.
In the planned practicals programme for EEE modules at the University of Sheffield, we plan to use simulation tools as part of a balanced diet of in-lab activitites, videos, datasets, remote access to in-lab equipment and hopefully take-home kits. This blog post concentrates on the simulation tools that we've tried and tested successfully, in the hope of helping others looking for remote practical inspiration.
Which Tool Should I Use?
There's a running theme to recent blog posts - always think about the activity learning outcomes.
If you want students to focus on real-world style circuit construction, choose a tool that provides that realistic interface. If you want students to gather data for presentation and analysis, provide pre-built circuit diagrams in a simple tool, rather than forcing them to also learn how to use virtual breadboards.
So, my recommendations are:
- To directly replace a construction and production skills task - Tinkercad
- To prepare students for practical hands-on Arduino/breadboard circuit construction - Tinkercad
- To gather and record data numerically or graphically - LTSpice
- To design experiments using real world devices - LTSpice
Tinkercad
An in-browser simulation platform, that allows drag and drop circuit construction. Constructing circuits looks and feels just like in-lab work, with breadboards, wires, components and common pre-built PCBs with sensors.
The outstanding special feature is support for both Arduino hardware and software - the simulator can emulate Arduino code just like the standard desktop editor, including most common libraries and the serial monitor interface. Code is easily copied between simulation and real microcontroller programming, allowing truly blended learning.
Tinkercad's built-in tutorials have excellent video content and can be embedded in a VLE, saving teachers time to concentrate on setting interesting assignments. For example, I asked students to complete 4 of the 6 built-in tutorials, then set an open-ended challenge to construct a temperature sensing circuit using buttons, LEDs, a buzzer and an analogue sensor. An example project meeting those specifications is embedded below.
This system replicates real equipment so well that it is ideal for replacing design projects - providing the brief is constrained to only require the range of parts available in the simulator. However the oscilloscope is not overly useful or representative of real instruments.
LTSpice
Clunky and not very intuitive interface, but powerful for simulation. LTSpice uses the tried and tested SPICE simulation methods to simulate circuits formed from discrete components and integrated modules. Circuits are drawn using standard circuit symbols, before simulation in time or frequency domains. There is no "real-time" simulation, so students won't see LEDs light up or motors spin, but they can explore voltage and current waveforms anywhere in any circuit, to aid understanding.
There is little built-in tutorial material, but I have recently made a 9-part series of tutorial exercises for first year students that will be open-sourced online soon - watch this space or leave a comment to find out more.
LTSpice can produce superb parameter sweep plots and data tables, making it great for data analysis and experimentation. For example, I have asked students to simulate resonant circuits and op-amp based oscillators. The students must choose their own frequency sweep parameters to ensure they gather enough data to clearly see features of interest, meeting learning outcomes in experimental design.
Circuitlab
A similar style to LTSpice but runs in a web browser. Fewer components available, especially in terms of ICs. However, the ease of use (no downloads required and more familiar keyboard shortcuts) can outweigh this for simple experiments.
There are a few example circuits already made, but there is little tutorial material overall, and some of the projects seem unfinished (the open source textbook with examples is a great idea), so the overall product does not have the complete shine of some of these other solutions. But for quick and straightforward design or measurement activities, the ease of use still makes this software a viable candidate for teaching.
Fritzing
Not quite free, it now asks for a small fee (open-source does not mean free!), but a leading open-source circuit layout designer.
Fritzing has a great visual interface, which is really easy to use. There is plenty of support from the Maker community as well, who have adopted Fritzing for sharing circuit designs. However, there is a major component missing - Fritzing does not include a simulator. Fritzing does not even include an option to export a file to run in an alternative simulator.
If the lack of simulator can be overlooked, Fritzing offers a simple PCB design experience on top of the visual component editor. This could make a great virtual introduction to PCB design, if simulated testing is not required.
Do you know of more good tools?
Leave a comment below to share your favourite tools - we'd love to know what you are using and how you are using it.
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