Understanding Electronic Circuits: Multimedia Learning Guide

Abstract

This package is intended to help students visualize the `flow of electricity' in a large variety of electronic components and circuits. The CD-ROM is organized on a menu structure, which makes it easy to navigate, whether in browsing mode or following the suggested order of topics. For each circuit, clicking on a play button simultaneously starts both the animation and the audio explanation that accompanies it. A slider bar allows the animation to be advanced or rewound. There is also the option of getting a text summary of the audio commentary. On many screens, a `maths' button can be clicked to bring up a screen of relevant equations. The initial section on basic circuit theory is designed as an introductory treatment for complete beginners. If the user follows the suggested route, s/he is first taken through a series of screens that show what a circuit is, explain voltage and current and their measurement, discuss the concept of resistance, and demonstrate short and open circuits. The circuits in this part are easily understood, containing only a battery, switches and lightbulbs. A colour code is used throughout to represent levels of electrical potential (although unfortunately this convention is not explained until the `understanding voltage' screen, which is number four in the sequence). This is an effective visual way of putting across the concept of potential drop, although the approach is slightly marred by a repeated error in the colouring of one type of parallel circuit. Additionally, some of the wording in this section of the audio is extremely confusing, e.g. `the voltage is a force' and `the light bulbs use up the voltage'. There are also some minor inconsistencies in the brightness shown for bulbs in series and in parallel, which would probably confuse novices, and an error in the animation for one of the open circuits. The link between current and rate of flow of charge is clearly made, and the difference between current and electron flow is specifically addressed in an early screen; however, the animations show conventional current as a series of moving dots in a way that this reviewer feels could easily lead novices or browsers erroneously to associate the dots with charge carriers. The second, much longer, section is entitled `components' and covers a good variety of basic components, not just the basic resistors, capacitors, diodes and transistors, but also thermistors, LDRs and LEDs, op-amps and digital gates. The introductory screen for each component type gives access to a description of the basic operation of the component, and to a series of increasingly complex circuits in which it is used. The workings of all these circuits are described via animation and commentary, using the conventions introduced earlier. Many of descriptions will be very useful to learners, especially for more advanced students starting to explore real devices. However, for novices the logical flow of the arguments is again marred by occasional errors (e.g. an apparent short-circuit through a resistor) and omissions (e.g. attention is drawn to the arrows on an electrolytic capacitor as showing which way round the capacitor should be connected, without ever actually explaining how the symbol should be interpreted in practice). The third section, entitled `circuits' is simply a menu giving direct access to some of the circuits already covered in section 2. The fourth and final section contains an introduction to systems, with examples of amplifiers, monostables, astables, buffers and decision makers, again using some of those included in section 2. Essentially these latter sections can be considered to be a reference library of circuits. A set of 20 worksheets is provided, showing circuits that students can build and experiment on for themselves, with suggestions for investigations they might make on the operation of each one. These would be an excellent resource for a supervized practical element of a course, although the lack of wiring information for components such as op-amp chips means that some teacher input would be probably be required to get the circuits working. Overall this could be a useful package if mediated by an expert, but is very much of the `look, listen and learn' style of instruction. It is to be hoped that future versions make more of the possibilities for genuine interactive learning afforded by CD-ROM technology.