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THE B.A.E.C. NEWSLETTER

No. 138, December 2000

Electronics and the members of the BAEC
by Eric Edwards GW8LJJ.

Electronics as we all agree, like it or not, is changing. However, that does not mean we will be left out in the cold, it could, in fact, be to our advantage. Let me take you back to the 1950's when, as a schoolboy, I entered into the world of electronics, well, radio actually. I made amplifiers and simple radios with valves and even a double superhet later in 1960's. My interest turned to tape recording, using reel-to-reel machines that were big and heavy. As I was, and still is, an avid constructor I built all my own associated equipment, which included audio mixers and effects units along with reverberation, and echo equipment. These were of valves and created problems such as hum and heat. Was I glad to enter the world of transistor construction as this eliminated all the earlier experienced problems. As I progressed with transistors my equipment became much smaller and easier to handle. I could use a transistor now, for example, as an impedance converter for the Ribbon and moving coil microphones instead of buying expensive matching transformers.

My hobby took me into television when I later obtained an amateur television transmitting licence. My television cameras, switchers, pulse generators etc were valued and were home-brew or manufactures and broadcasters, redundant units. I later replaced the commercial valued gear for 'homebrew transistor projects. This increased my working space and reduced my electricity bills. Later, as I was playing with effects units for television, I entered the world of IC's and what a difference that made. My television effects units and mixers could be made smaller again and actually do more. So change is not necessarily a bad thing!

We are amateurs enjoying a hobby of our choice, but are not competing with the commercial boys, it would be foolish to try and besides, it would be no point in doing so.
We get out of our hobby what we put into it. Why do we carry on? What is the main object of our hobby? Well as far as I am concerned, I use the hobby to do what I want it to do! I use the hobby as an instrument of achieving satisfaction. If I want to perform a simple task of say, turning on an LED when a pre-set voltage gets too high, I will use a simple circuit. I have a choice of what I can use and I will construct a circuit out of the components I have at hand or that I can obtain cheaply and readily. I can use a resistor network, or a comparator circuit or even use a PIC; those magic eighteen pin devices that seem to be able to do anything you ask it. I will use a simple resistor network as first choice, not the microprocessor chip as that would be an over-kill. But it is my choice. I can use whatever I want! That is the beauty of our hobby as we decide what to use and not what the market dictates. If I want to build an audio amplifier using valves I will, and there is no reason on this earth why I should not. However, to build a multi-tasking unit to perform all sorts of things simultaneously, I would use a device that would simplify the circuit design. A few years ago I designed a video switching unit that was able to change four video sources (CCTV cameras) by pushing one of four momentary push button switches and by pushing a fifth button I could get the cameras to switch sequentially. Not only that, but I could select with the same four buttons, which order to sequentially view the cameras, and during the switching sequence I could pre-set the timing of the switching rate between the cameras using, again, the same four push buttons. I could also jump in to select and hold a camera view. I could also alter the switching sequence and timing rate at any time I wanted. This complicated unit uses TWO ICs, one of which is a video matrix and the other, yes you've guessed it, a PIC. Try doing that with TTL or transistors, or dare I say valves.

Another interesting field of electronics is surface mount (SMD). If you get started in using surface mount components, the storage space will be reduced enormously. I am storing surface mount resistors, capacitors, diodes, transistors and integrated circuits in compartment boxes that use less space than a quarter of what I use to store just quarter-watt resistors. Good, or aided eyesight and dedication to small circuit design are the requirements of these devices however. It is a good field to get into, as long as you don't mind loosing a few devices as they fly out of the tweezers and onto the floor never to be seen again.

It is over forty years since I started in electronics and I have seen many changes and although I accepted these, there were some of the challenges taken away because it was made easier to achieve an end result. I later learned this was better for me as I could produce projects much cheaper and could get the circuits to do more. Our hobby is a `hands-on' product and computers have taken that away. Well, if you allow it to that is. A colleague and I were chatting a little while ago when this topic arose. He said. "Computers are great for electronics. I don't need all the test equipment now as it is all on screen". I did not comment but thought, how sad. But then, he was studying for END and his interest was purely of an academic nature and not as a hobbyist. We, who use electronics as a hobby, have a lot to be thankful for. I work in an electronic environment where all my work mates are electronic technicians, and I still get asked where is the cheapest place to buy a 9-volt power supply? Some are even amused how I get a pilot bulb to flash using just the contacts of a relay and a small power supply. We are a special breed, of electronic guys as we use electronics instead of just talking about it. Anyone can, after reading a couple of chapters from a textbook, explain how a circuit functions, but ask them if they have actually done it to prove the circuit? Another `student' came to me and asked why his circuit did not work although he designed it on a computer using dedicated software. I explained that unless you are using the components to the specification of the software types it is hardly likely to work! We don't need computers to get our circuits working, we need experience, and that comes with time and practice.

I stated that I used a PIC in a special project that I built a little while ago. These devices are so versatile and easy to use. I did not know anything about PICs or programming in general a few years ago as my background was radio and television and I was not interested in programming of any kind. I soon altered my opinion however when I discovered that I could do a damn sight more with one of these compared to quite a few ICs and associated passive components. I learnt to program a PIC using a form of BASIC language. I said I had no knowledge of programming so everything to do with programming was foreign as far as I was concerned. After a little bit of persuading and seeing what these little devils could do I was hooked. I tried a couple of programming examples and soon found that I was taking projects using a PIC into work and amazing and amusing my colleagues, and '; I created a great interest in PICs, and I was talking PICs every day with workmates and this inspired me to bring in more projects just to show how versatile and more importantly, how easy it is to programme these devices. I do not use mnemonics as I find `BASIC' is much more, wait for it...user friendly.

The PIC projects that are found in magazine articles are usually programmed using mnemonic coding. I cannot get on with that type of programming and anyone who has done no programming at all will not want to either unless he/she (you have to be careful), wants to learn machine type programming. I use Basic as a programming language because I can `talk' to the PIC in plain (well almost) English language I would like to start a mini-series of PIC programming using this method, and when you see how easy it is to programme these devices, you will soon be programming yourself. If you want to!

I would like also, to see a mini-series of `starting in electronics' as well. This would be ideal for the newcomer as well as the experienced. I am often asked, when confronted by a trainee technician, why I chose a particular value component in a circuit. I have been asked if it is possible to use a higher voltage working capacitor and a high wattage resistor in a circuit. These may be questions that a lot take for granted, but were they obvious when you started in electronics? These type and other types of questions can be answered in a mini-tutorial through the pages of this newsletter. This newsletter is dedicated for the beginner, with the more experienced amateur being able to help them. The commercial magazines have to cater for the majority which are not necessarily all beginners. So let's have some input from the experienced guys to this newsletter to show the others how it is done, and likewise input from lesser experienced members would be of an enormous value to tell everyone what you are doing or want to do!

The best thing about us and our hobby is that we can use, within reason, whatever we like to produce a project and the more we practice the better we shall be at it... keep practicing, and more importantly, through the pages of these newsletters, keep in touch!