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spare spare spare . .. . . . My 'homebrew' tuner/amp (Mullard 50W) circa 1972 . Power amp section on LH side(mounted on hinged heatsink panel containing power output transistors) . Hinged panel lifted, revealing pre-amp section beneath |
This web-site describes my vintage hobby interests, the origins of which I will explain below. My interest in technology first began when I started playing with electronics as a young boy in the early 1960s. At the age of about nine years, in between playing with model trains, I began experimenting with making up simple circuits involving batteries, bulbs, buzzers, electromagnets, motors, telephone earpieces, carbon microphones, etc. The year was 1963 when, at the age of ten, I started dabbling with crystal sets. One day my father had been on a business trip to London and had brought home (from Lisle Street probably) a bag of around 50 unmarked and untested Ediswan 'top hat' germanium transistors. With these, he taught me how to make simple amplifiers, and I soon learnt how to use them to add gain to the outputs of crystal sets to drive telephone earpieces and small loudspeakers at a decent volume. I soon started experimenting with reflex receivers, building circuits taken from a book by Clive Sinclair. I remember that by the age of eleven I had constructed a small portable radio housed in a home made wooden enclosure driving an internal loudspeaker. I recall taking the radio into school to show it off to my friends, and being extremely disappointed when they all refused to believe I had built it myself! Things progressed, and by the age of thirteen I started playing with RF oscillators and discovered how to turn these into low power CW transmitters on the MW band with a range of a few hundred feet (all very naughty of course - tut tut!). I then learnt how to apply speech amplitude modulation to these carrier waves using a microphone, audio amplifier and coupling transformer in series with the battery supply. By now I was receiving my first introduction to valves, which during the early 1960s were still very much around. I recall we seemed to have a shed full of old valve tellies, radios, boxes of junk and the like, which my father would frequently raid for parts to keep the radio and TV sets in the house in working order. I soon learnt about valve circuits and started to dabble with them myself, gaining a very healthy respect (the hard way of course!) for HT voltages and live mains. By the age of fourteen, in addition to constructing and repairing of transistor radios, I was now finding my way round faults on valve radios, TVs, etc, and I had also constructed a two-valve SW radio receiver from a design in Practical Wireless. When I was fifteen I acquired a circuit diagram for an early Cossor oscilloscope and used this as a basis to construct my own, using a VCR139A CRT mounted on an old TV chassis stripped of its components (I still have this old tube in the garage, but alas the chassis has long gone!). This project will always stick in my mind, as it had a curiously named 'Puckle' timebase. After that, I went on to build yet another oscilloscope using a VCR97 CRT and a more refined circuit design. In my mid-teens, as with many other teenagers of the time, my interests got drawn towards loud music. Having dabbled with push-pull valve amplifiers that my father had once built, I managed to acquire some germanium OC25 power transistors plus a circuit diagram from a renowned designer of the time named Dinsdale. From this I constructed my first transistor 10+10W stereo power amplifier. After having kept this 'relic' for so long, much to my regret now it went to the crusher not many years ago. But never mind, I did at least keep the next one I constructed. This was the Mullard 25+25W amp, to which I later added a home made VHF tuner, mounting the whole lot in a handsome teak veneered case. Some years later I converted the tuner to stereo by adding the first of the new breed IC stereo decoders that were coming onto the market (early 70s by now). What I've described above is only a mere fraction of the things I've built or experimented with in the electronics field during my formative years. As a 17 year old, I was also by now starting to develop an interest in the mechanical workings of motor cars, necessitated by the need to keep my first car (a Standard 10) running on a budget of next to nothing. My interest with cars could form the basis of another potted history, covering everything from engine rebuilds to transistor ignition systems. Suffice to say, from this was born, at a later date, my interest in vintage motor vehicles. In a nutshell, all this schoolboy tinkering with radios and subsequent introduction to car mechanics took me through to the start of a college education in engineering that led into a professional career in the electronic engineering field. In 1980, I became a Member of the IEE and registered as a Chartered Electrical Engineer. For the record, I did my undergraduate studies at the Mid-Essex College in Chelmsford, commencing in 1971 and departing in 1975 with a College Associateship (a somewhat rare qualification of the time roughly equating to BSc. Hons). Looking back, I feel quite fortunate to have undertaken my academic studies in a town that had such close ties to the early development of radio (the significance of which I appreciate more now than I did then). Marconi and the English Electric Valve Company were certainly big names in Chelmsford in the four years I spent there, with many of the college students being sponsored by these firms. I really enjoyed those years at Chelmsford - happy days!! |
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