Magart

Magart

Compiled by Liam Maskey

Temperature measuring systems are always a favourite of electronic hobbyists and January's EPE features one involving the use of a diode as the sensing element. The project is quite detailed as to how the diode sensor works and would serve as a useful introduction to the principles of this sort of thing. The circuit is simple in design, using only two ICs and a handful of discrete components. The author claims the range of the probe is from 0 C to 125 C. I am unsure of the probes accuracy as the author ambiguously states, "The project, however, despite its basic simplicity, will read 2% at worst and over the lower ranges of the scale may be better than this."

The following is a contribution from Herbert Howard. He writes "ETI seems to include one major article in each issue, and these are often about recent developments. In the last issue of last year (Vol. 26 Issue 13), there was an in depth review of digital photography techniques. Also in this issue was the second part of an article about the construction of a high performance MW receiver, the first part appeared in Issue 12, which I did not see. Details of a loop aerial for this receiver will appear in the next issue. The first issue of this year (Vol. 27 Issue 1) mentions that Maplin are marketing a digital camera, the Mustek VDC-100. The price quoted in the magazine was 99 ex. VAT, but in the Maplin catalogue it is given as 149 including VAT. This camera has a maximum resolution of 640 x 480 pixels and can store ten images at this resolution or twenty at the lower resolution of 320 x 240 pixels. The camera has a focus free lens from 9.5cm to infinity and automatic exposure. Supplied with the camera are a power adapter, batteries (4 AA), and a carry pouch. A cable for transferring images to a PC is supplied, together with Photoplus software for editing and cataloguing images. Also provided are a TWAIN driver and Mustek Photomaster - whatever these may be.

The main article in this issue is "Inside Microcontrollers" and is a comprehensive review of all the various types of microcontrollers that have been produced since the Intel MC848 appeared in the mid 70s. It deals with the architecture of these devices and sets out the range of devices available, including the widely used PICs, and also summarises the various requirements for programming these...

You will have seen the data sheet on the Arizona Microchip range which was included in a recent issue of EPE. The March, April and May issues of this magazine will contain the three parts of a PIC tutorial...

Some other articles I found interesting in the same ETE issue were: constructional details for an infra-red remote control system and a comprehensive article on DC voltage converters by the prolific writer Ray Marston.

In the February 98 issue of Electronics World, John Lindsay Hood has returned to a unit he has dealt with several times before, namely a high sensitivity distortion meter, incorporating a wide range millivoltmeter which can be used independently. Another article gives the circuits for a multi-band direct conversion HF receiver which uses CMOS switches (74HC4066) in the mixer instead of the more usual diode ring. The receiver is designed for the amateur bands 7, 14, 21 and 28 MHz. Also in this issue is the second part of a series on "Understanding Capacitors".

For those interested in courses, January's Elektor launched "Introduction to Digital Signal Processing", Digital Signal Processing (DSP) was one of the subjects covered during my Postgraduate studies in electronics. The latter course was heavily into mathematics with very little practical element. The Elektor course allows people to participate at their own level, involves experimentation and covers a fair bit of DSP topics. The course software comes on a CD-ROM, and as well as having a CD-ROM drive your PC will need a sound card.

March's EPE featured "The best introduction to using PIC Microcontrollers ever written", I can't vouch if this is true but going by the first article of the three series it certainly looks as if it will be an excellent course.

The first article builds on the PIC programmer designed by Derren Crome and uses the software provided by this project. The article assumes no prior knowledge of PICs and takes the reader through the very basics of this type of microcontroller. The series is practical in nature and to this end a circuit design is given that allows all the series projects to be built and tested.

Finally, Joseph Vella from Malta writes about the Car Immobiliser project published in the December issue of EPE. He says "The circuit is very interesting, simple and very compact. The circuit concept is basic yet the protection it provides is powerful. The key which controls the immobiliser is built around a resistance balance which only the owner of the immobiliser will know".

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