This is what I call my way of building things in the 1970's. As a student at Ottawa University (Uof0), money seemed to always be tight for equipment that I thought I needed (when the profs needed something, the only ceiling on their spending appeared to be the size of their grants). I have a very strong aversion to doing something manually when I know it can be done automatically. The only problem was that I had a very limited budget to do this on. The entire budget for this timing device was $200. Most of this money was spent on buying the then expensive SRAM's (16 2102 1024x1 capacity) which were about $7 each back then, a UART ($25) and perfboard. Also, I had to buy things like 74191's and other MSI chips that I couldn't scrounge easily.
One thing I had done before this project was to order a large number of wire wrapped boards for a couple of dollars each which have about 150 SSI and a few MSI IC's on each board. The other usefull item on each board were the massive number of wire-wrap pins. IC's were desoldered from the board and those which survived this process were set aside for my project. 16 pin connectors were needed to connect up the various subunit circuit boards, and these were made by taking blank 16 pin sections of the circuit board, sawing them out, and then using the wirewrap pins to make a connector (a photograph of this is given in overview photo section). Diodes for passive diode and gates were obtained from my large supply of other surplus circuit boards that I had accumulated over the years. Wire was supplied as a very long length of multiconductor telephone wire which was dumped in the garbage of the Uof0 medicine building. Chassis for power supplies were made from various junked bits of tube based equipment which provided heavy metal boxes to attach things to, and were great natural heat-sinks. Filter capacitors for the power supplies were obtained from other junked equipment. The only thing I had to supply was time, and this seemed very plentifull at that point in my life.
Since this time, I've attempted to use junkyard engineering techniques whenever possible. I find it now unbelievable what people throw out in Vancouver, and I have retrieved 5 functioning laptops from dumpsters which are perfectly useable as standalone controllers. My stereo system utilizes a power amplifier found in the back alley, my speakers have a similar origin and the only audio CD player I have was found in a dumpster. Until my girlfriend objected to picture quality, all of the TV's I used were discards usually discarded because of a single bad tube which can be diagnosed in <5 minutes with most of the brainwork involving figuring out how to remove the back casing of the TV. I could go on for quite a while about the riches one finds in garbage, but this would be off topic.
Now that I'm a doctor, I no longer have time to dumpster dive or frequent electronics surplus stores. I do my dumpster diving by proxy by paying a number of fulltime dumpster divers to retrieve certain items of interest (I still can't get over how many laptops people chuck into the garbage); surprisingly the items that I want seem to have no resale value. The infiltration of electronics into everyday life is so pronounced that I have no difficulty in getting almost all the parts I need from dumpster divers. Any of the recovered laptops I have would have allowed me to impliment the timing device functions just by using a few pins from the parallel port.
One of the reasons I still remain attached to junkyard engineering is that it allows me to take apart things that I would normally never consider spending money on, and I do worry about how to fix things when one can't get replacement parts (like in the event of a major natural disaster). Also, if one knows how to scrounge, one can build things under budget and when one is given more funds to build something, use large chunks of them for more fun things like beer.