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I PRODUCT SHOWCASE I The Electronics Workbench This software package from Emona Instruments is designed to enable on-screen simulation of analog and digital circuits, complete with testing by simulated instruments. It could be highly effective as a teaching aid for schools and technical colleges. By LEO SIMPSON One of the major problems in teaching electronics is the need to spend large amounts of time in setting up circuit demonstrations for or during classes. Most circuit princi ,Jes are best taught using theoretic l examples which can then be bacJ....ed up by practical circuit examples. However, the time spent setting these up can often make this impracticable. This Electronics Workbench package , produced by Interactive Image Technologies of Canada, enables circuits to be simulated on the computer screen, giving lecturers and teachers more time to spend on other things. Our review copy was of the profes- sional version which provides a VGA display and unlimited components in a circuit. The software comes on four floppy discs and the auto-installation system makes loading the software into your computer simple. The Electronics Workbench comes as two modules: analog and digital. The analog section provides you with four test instruments, as follows: a voltmeter which can show volts , amps, ohms and dBs; a 2-channel oscilloscope which operates in a way similar to a real one; a function generator which produces sine, triangle and squarewave signals from lHz to 999kHz; and a Bode plotter for dis- playing frequency responses. Once the software is running, the right-hand column of the screen shows a 'parts bin' which contains the icons to all the available parts you can use in circuit. You have an unlimited number of each component so you don't have to worry about running out of circuit parts. In fact, the limit on circuit complexity is more a matter of computer speed rather than the allowable number of parts; larger and more complex circuits take longer to simulate. To lay out a circuit, you simply click on the desired component with your mouse and drag it to the desired location on the screen. To join up components, you move the mouse to one of the ends of the component until the connector of that component lights up as a small black box. You then click and drag a connecting wire between that component and the next component. Both the analog and digital sections use the same layout procedure. The digital section's parts bin contains all the basic gates and flipflops, again in lr Ji l 00 -r = = 1 (,(1 l I,,,~~: ~t .:~. oow,n ' . .f 1)0 l-< f \ : ·$_; 1 0 0 kO ;-,: ~c• ; -~ \.:..... __ This 3-stage common emitter amplifier is one of the sample circuits provided and has both the dual trace CRO and the function generator connected in circuit. Note that the CRO shows input and output traces. 56 SILICON CHIP i This circuit demonstrates the software's ability to provide Bode plots of a Wien bridge network. The right hand column shows the analog parts available. These are brought to the screen by clicking and dragging. unlimited quantity. The test instruments in this section include a word generator which can hold 16 8-bit words; an 8-channel logic analyser; and a truth table/symbol converter capable of turning truth tables into circuit representations. This allows you to set up a digital circuit and go through the analysis showing all the possible states. The package also includes what is called a Hypertext help system, which can be tailor-made to suit your requirements. All you do is to type the text you wish to appear on screen in an ASCII-format file on any wordprocessor. This feature makes it suitable for use alongside most textbooks. Components such as op amps and transistors are assumed to have standard parameters but you can customise these to simulate virtually any device. One point we should make is that this software package is not like some of the more expensive circuit simulation packages which have comprehensive libraries of most commercially available op amps and transistors. Instead, it is intended more as a teaching and tutorial package rather than for design testing simulation, although it can do this to a limited extent. It is not possible to link analog and digital components together. In a classroom situation, where analog and digital electronics tends to be segregated, this would not cause a problem but it makes it difficult, if not impossible, to analyse many of the circuits de- scribed in SILICON CHIP. Some of the supporting literature which comes the Electronics Workbench suggests that this software package is ideal for practical classes with students because it allows them to build. circuits without the need for components, test instruments and the like, saving the school or college money. We hesitate to fully agree with this because as useful as the package may be, it cannot fully demonstrate to electronics students the practical problems that come up in circuit design and layout; eg, earth loops in amplifier design or over-biasing a class AB audio amplifier so that the output transistors blow up. Interestingly though, if the input of the simulated oscilloscope is not grounded, 1 volt of 60Hz signal is added to the output waveforms. This simulated hum pickup by the circuit is a small but practical point which would often be overlooked by students. The Electronics Workbench comes in three versions: the personal version which has a monochrome display and can run circuits with up to 30 components, and costs $149; the personal plus version which has unlimited components, retailing at $299; and the professional version with both EGA and VGA capabilities for $429. Each comes complete with a useful reference manual which shows how to install and operate the software, as well as explaining briefly how the software simulates the circuits. - ii ····- • .. ~- . .... . - Our first full catalogue of our huge range of electronic components and kitsets is nearing completion and will soon be delivered to those requesting a copy - FREE! To secure your copy, please fill in the coupon (or copy details), send together with 3 x 45<1: stamps for postage and we'll send a catalogue, hot off the press! You'll also receive updates, bonus offers, specials, etc. during the year AND each month until June you will be in the draw for a free SCOPE PH20 soldering iron! .::, =:. Q 'eLJ / Please send me a FREE catalogue 0:;)t I have enclosed stamps for postage Name: . Address .. .. . .. Postcode ,\ ALL ELECTRONIC COMPONENTS l i 118 · 122 Lonsdale Street. Melbourne. V,c 3000 l:L.. Telephone (03)6623506 Fax (03)6633822 Our conclusion: this software could be very useful to students and lecturers in a structured electronics course. For further information, contact Emona Instruments, PO Box 15, Camperdown, NSW 2050. Phone (02) 519 3933. - - . .·.... . . ==~~~"';:=J;&c-~=:-, ~='.'- - - · ·;:'.::.::: ,:;-:=;0=2:s~:'.-;=:-·:- - - - - -~ ----··- C·---c_,--, ·· - -=---=-=:--: • >·=-•--:;___.,.,. l <at> .. 1jjl ·.jiiQ}~ · < . < -: 1 i: ..- i.!..51- -~~,:~~~-cc=~. -.·· ---l~;-~:8? ~~~~-·-~---r-:-·_ ,- - . . _J -~ _J·!··-11!,' ....-I.••.···.· .i.~ .,._·_:_···r· .·_ •..· i r - -> :::-' ------ . I .. +·· ·,,,..,--;:::;_--::>--.~·-t-~~ A logic analyser and word generator make it easy to step through a 7-segment display driver. These instruments are brought down by clicking and dragging them from the top screen row. -x-_,,...:::1-.,\.. ...._ '--_,..:-· ,,- ··-:=::,-~;;:, - 1: i v.,· -t'.· '.,:. ·r.· .~ l Complex digital circuits can be simulated by the Electronics Workbench. This circuit is a BCD decoder which is based on simple logic gates. The right-hand column shows the components "parts bin". APRIL 1992 57