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| Clive Sinclair - what a cheap skate! |
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| chris_leyson:
A long time ago I had heard that the Sinclair Micromatic had used cheaper out of spec transistors, not sure whether it was true or not and it could easily have been confused with the Micro-FM radio which used out of spec transistors because their gain was too high. See link to Richard Torrens page below. I could never get my Mk2 Micromatic to work, it might have been my soldering or a bad ME4102 transistor. Clever bit of design for a reflex TRF though. The mica compression trimmer was a classic. I used a Sinclair Scientific calculator for a while but its accuracy wasn't that good and there was a calculator shoot out published in ETI magazine. The Commodore SR-1800 came out as the winner and I've still got mine somewhere, used the Sinlcair for its multiplexed LED display. http://diy.torrens.org/Sinclair/inside/Duncan.php |
| Brumby:
--- Quote from: chris_leyson on September 05, 2020, 09:55:54 am ---..... had used cheaper out of spec transistors --- End quote --- Here's the thing - Something described as "out of spec" simply has parameters that are not within the range defined by the designer - BUT - that doesn't necessarily mean those parameters will be outside the range of functionality for a particular application. It is not inconceivable to produce a widget which contains out of spec components and still work. Sinclair's RAM exercise being one example. This could also apply to, say, a transistor whose maximum voltage is specified at 25V, can't handle more than 15V but is going to work fine in a 9V circuit. In this case, replacement with an "in spec" part should restore operation. I daresay you could then have a component that is "out of spec" - but it is one of those out of spec parameters that enables it to function in a particular circuit. Here, replacement with an "in spec" part will not restore function. "In spec" is not as important as "suitable for purpose". |
| tggzzz:
--- Quote from: CJay on September 05, 2020, 11:04:46 am --- --- Quote from: Brumby on September 05, 2020, 10:50:49 am --- --- Quote from: chris_leyson on September 05, 2020, 09:55:54 am ---..... had used cheaper out of spec transistors --- End quote --- Here's the thing - Something described as "out of spec" simply has parameters that are not within the range defined by the designer - BUT - that doesn't necessarily mean those parameters will be outside the range of functionality for a particular application. It is not inconceivable to produce a widget which contains out of spec components and still work. Sinclair's RAM exercise being one example. This could also apply to, say, a transistor whose maximum voltage is specified at 25V, can't handle more than 15V but is going to work fine in a 9V circuit. In this case, replacement with an "in spec" part should restore operation. I daresay you could then have a component that is "out of spec" - but it is one of those out of spec parameters that enables it to function in a particular circuit. Here, replacement with an "in spec" part will not restore function. "In spec" is not as important as "suitable for purpose". --- End quote --- Absolutely, but the reason you buy parts which 'meet spec' is so you can design to those specs. If you buy factory rejects like Sinclair did, then there's no guarantee that they will perform the same even in the same batch, never mind the next batch, it pushes up production cost because you have to 'select on test' for every product and it reduces reliability drastically. It also makes repair far more difficult because there's no guarantee you can buy the re-marked parts, no guarantee you will get one that matches the foibles of the unit you're repairing and no guarantee you can find out which other components to change to make it work... It's fine to buy bags of reject parts as a hobbyist, it used to be a big market and pretty much every electronics mag was teeming with ads for 'bargain bags' of factory reject components, you bought by weight not quantity, for production, it's a stupid trick that can wreck your reputation. --- End quote --- I still have some of those "BC108-like" transistors :) The insider in http://diy.torrens.org/Sinclair/inside/Duncan.php notes that Sinclair's business model included large numbers of "return and get your money back", and that the Sinclair staff could often rescue the kit. When they did that they offered the punter the their money or their fixed kit, and the punters were often grateful. |
| Berni:
Its pretty common for companies to sell partially working silicon chips for cheaper in order to avoid just tossing them in the trash. Pretty much all the SD cards you have contain just partly working flash inside. Due to the push for density the yield is awful on flash memory. So even the top tier cards have some leftover capacity hidden away to cover the dead pages. The chips with too many dead areas are instead sold as half capacity memory chips. AMD used to sell 3 core CPUs. Why would they make a 3 core chip? Because these are actually 4 core chips with one of the cores dead, but the chip is designed to easily disable that core. Nvidia does this commonly where the xx70 models (2070 1070 970...) are actually the same GPUs that are used in the higher xx80 models(2080 1080 980...) except that too many cores are dead, so they disable a certain number of cores and sell it off as the lower model. Even 100% working chips are binned. For example intel sells the same CPU die under multiple partnumbers depending on how well it did on the final test stage. If a chip is seen to perform better under high clock speeds it is sold as the overclocking K variant, if the chip fails the test at normal speed but passes the test at a lower clock speed then it is sold as a lower clocked model. If a chip shows particularly low power usage then it is sold as the low power S or T variant. |
| vk6zgo:
Many BJTs are/were allocated their type number, depending on their measured beta. If you buy the base model car, it has many of the "bits" from the upmarket ones, just not used, so what's the difference? |
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