The sine-wave generator is an essential tool for electronics education, indeed it plays a central part in demonstration and experiment. The conventional ‘audio signal generator’ found in most schools and colleges is, however, not always the most convenient instrument to use. How often has a student experiment lost its impact (and caused confusion) through the student having to change frequency range and then to track back across the whole range to start at the beginning, with all sense of continuity lost? And is it not an unwise teacher who puts together a demonstration of, say, resonance, without carefully selecting component values that put the frequency of interest somewhere near the centre of the decade range available for a continuous sweep?
A few weeks ago, teachers were introduced to a new interactive exhibition near Winchester, 'Intech'. It was the result of a long and hard campaign spanning many years. In Paris, over 30 years ago the 'Palais de la Decouverte' had enticed youngsters to experiment with electricity, mechanics and even relativity with hands-on exhibits. For many years the British science museums have warned 'Do not to...
The idea of extracting power from the wind is almost as old as civilisation itself, with records of existing windmills back as far as the 17th century BC, the time of the Babylonian emperor Hammurabi. Although mideastern countries possessed such knowledge, windmills were not introduced into Europe until the crusaders brought them back in the 13th century AD, but by the early 19th century there wer...
Some years ago when the AEB A-level Electronics Systems syllabus was updated, the following work on sampling was introduced: time quantisation, sampling rate and Nyquist criterion amplitude quantisation and resolution quantisation distortion. This seemed at first sight rather daunting. The sort of material which might appear in second year university courses on communications was to be presented t...
A previous article (ESN, Spring 1989, p. 33) outlined the way in which I saw microcomputer interfacing developing over the next few years. However, the pace of development is so fast that some of these 'future' interfaces are already with us, hence a further article is now needed to explain what is, or shortly will be, available.
In recent months there has been considerable debate about the future style of science education in schools. Interest has been focused on the likely balance between knowledge and understanding, exploration and investigation, communication and the ability of students to develop a critical awareness of the nature of science and how it is applied to their own lives.
Control technology is an exciting new area for many schools and there are many commercial solutions available to solve the two main problems of how to control your motors and how to get your sensors to send suitable signals back to the computer. Just which computer and software to use is another problem. The range of equipment available for PCs for instance is enormous (and so is the cost in many ...
Gor looked at the unhappy youth squatting on the floor of the cave. He saw bleeding knuckles gripping two misshapen lumps of flint. The lad's animal skin had been badly cured and was hacked, rather than cut, into an attempt at shape. That was the real cause of his trouble. In trying to chop up dinner he had shattered his family's knife.
This year marks the tenth anniversary in Britain of the first microcomputer interface for schools. This was a Commodore device, which had four digital inputs and four digital outputs and ran from the user port of the PET 2001 microcomputer via a set of simple control programs. The PET 2001 itself had 8K of RAM, its screen resolution was 4000 dots and it stored programs on cassette tape.
A technical description of two shaft encoder systems is given. Whilst being useful in their own right as notes on instrumentation the main purpose is as applications of some common electronics principles. The obvious version of the encoder, with straight binary coding, is found to work poorly and a Graycoded version is introduced to get over this difficulty.
This article gives a description of the design, construction and performance of a home-built pH meter comprising pH electrode, signal-conditioning system and BBC Microcomputer. Unlike conventional meters, its hardware is kept very simple. Most of the signal conditioning is achieved by software; the hardware part consists of two elements only, a stable voltage reference and a very-highimpedance vol...
