When I grew up in the 1950s the only supply of easily available electronic parts, that kids could get hold of, came from junked wireless sets (radios) got from the local tip (rubbish tip, garbage dump). Bliss was finding a radio chassis with the valves still un-smashed.
We learnt to substitute from an early age and this gave us a deep understanding of what you could do and not do with the then current technology. I made my fair share of valve plates glow red and turned a number of valves into flash bulbs. But by the end of it I knew what I was doing, to the wonderment of my parents. When transistors arrived in the 1960s their tolerances were so wide you could just about put any one in any cct and it would work. I bought 100 cheap factory-second transistors with no markings. Just finding out which ones worked was an ordeal. I'm sure more started out working than I actually ended up with, but by blowing them up I soon learnt what not to do and what I could get away with.
I believe Innovation in Electronics in Australia, without a doubt, stopped when a particular editor of a particular Australian electronics magazine said in a particular issue that as from that issue no more junkbox circuits would be published. From then on only circuits containing new components that were available from the leading retail electronics stores would be published.
Just to refresh your memory, a junkbox circuit was one in which a range of components were specified in each cct position to cover whatever components you already had in your junkbox. You could build the cct without having to buy many new parts. Also by substituting parts you soon got to know how the circuit really worked and in the valve days any experimenter worth his salt could design a working audio amp.
Once the junkbox ccts stopped coming it didn't take long for the retail stores to start selling kits for the ccts in the current electronics magazines. Innovation like charity begins at home and I believe this editor has done a big disservice to our young budding innovators. Now the innovation is done only in the labs of the magazines and not at home. I wonder how many of the staff of this magazine started out with junkbox ccts. (Mind you, with 10% GST on all the electronics textbooks aimed at children, the Govt doesn't want any young budding innovators either.) Now dont get me wrong. I think kits are a great way to quickly build a piece of test equipment or what have you, but they teach you nothing about electronics except assembling kits, cleaning copper and soldering. No one in their right mind would suggest that filling in the numbered squares on a sheet of canvas, with numbered paints, actually teaches you anything about painting, even though you may end up with a copy of a masterpiece. Same with electronic kits.
Another thing about kits is that they are made to sell as cheaply as possible and usually contain the latest whiz-bang do-all black-box IC. A number of years down the track if the IC blows you can forget about a replacement and that's the end of the kit. One good thing does come from this, however. You'll soon end up with a nicely stocked junkbox. Now if you only knew how to use those parts for something.....?
The next page will be presented in four windows. Three small ones across the top for the circuit diagrams and a large window at the bottom for the text. It is presented this way to enable the circuits to stay on the screen while you scroll the writing. You'll see scrollbars on the small windows at the top of the next page. While you can use them to scroll, you dont have to. They are only there because in some dumb browsers, if I turn them off to get more pixels I cant scroll either. All you have to do is click on the underlined figs. in the text and the monitors will scroll automatically. For those of you who are optically challenged, just click on any of the monitors to get a magnified view. Then click on the magnified view to return to normal. The first time you do this will be slow but from then on it will be a lot faster.
The CRO sections dont have any diagrams as yet. They are coming so please be patient.
Please let me apologise in advance for any errors you may find. I've read it a million times and I seem to find an error every time. Fingers crossed that the million+1 will be ok.
The page may take a minute or three to load as the html file is 377kb and 232 circuit diagrams come along with it.