by Dr Dave Wonnacott, CTI Physics Coordinator, University of Surrey
March 1998
The latest version of this electronics package has just been released and incorporates a swathe of new features which significantly improves this already-excellent teaching software. The review is by Dave Wonnacott, CTI Physics Co-ordinator.
As with any software package, there are good designs, bad designs and mediocre designs. Many electronics packages fall into the latter category simply by virtue of their 'dryness'. It is hard to enthuse about (or be enthused by) software that offers nothing but pictures of electrical components to jigsaw together and the occasional flashing bulb. A good package, of which there are too few, will combine an extensive array of components with some feel that one is doing electronics in real time and in a real sense. Crocodile Clips is a 'good' package.
Crocodile Clips v3 immediately impresses. This small package, coming in at a fraction over one Megabyte for the demonstration version (and between 2 and 3 MB for the full version), contains an impressive array of features. As well as the 'trivial' batteries, switches, resistors, and bulbs, Crocodile Clips has meters, logic gates, integrated circuits, audio components, semiconductors and thermistors, and now version 3.0 adds mechanical components like motors and gears, springs and masses, and solenoids. Assembling them is simple too - just click and drop. Wiring the ends together with the mouse click-and-drag can be trick, but not overly so, and even that tends to encourage good circuit layout. Furthermore, entire sections of circuit can be cut-and-pasted to repeat identical sections of layout. The use of mechanical components (an innovation for Crocodile Clips) has been implemented well, with motors, gears, and crankshafts meshing seamlessly with the electrical components.
Once the circuit is activated (for example, by turning on a switch), current is seen to flow through wires (indicated by arrows), capacitors charge and discharge (with pluses and minuses on each plate), LEDs flash, and gears turn. This is, indeed, a virtual workbench, and the animation is excellent.
Oscilloscope probes are provided and a separate trace window is available to plot the variables against time. Again, this is clear and easy to m2_ate , and reading form the scales provided causes no problems. A right-click of the cursor anywhere along the wires displays the instantaneous current and voltage values in a small pop-up box enabling the student a quick look without having to set up probes and a display. Sine-wave, square-wave and triangle-wave generators are available to provide test inputs, and both oscilloscope output and sound output can be written to external files.
Eighty-one example circuits come in the demonstration package covering circuitry as diverse as beating between nearby frequencies, flip-flop circuits, demonstrations of Ohm's law, and even household circuits like fridge lights and stair lights. With the mechanical options, demonstrations of inertia and acceleration, and even simple harmonic motion become possible. Crocodile Clips 3 is now considerably more versatile than just 'an electronics package'. It is clear that the ease of use of this package would present few problems in a lecture environment. Circuits can be set up beforehand and saved to be loaded when required, mitigating 'finger trouble' in front of a class. As for 'laboratory' use, each pack contains activities and example circuits which can be used as exercises for classes or as a resource for teaching, and there are a number of texts and other software packages which are compatible with Crocodile Clips (for details see the resource page of the Crocodile Clips website). Circuit diagrams can be printed straight from the screen or saved as bitmaps, and 'output data' can be saved to files for subsequent analysis.