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Fatmangolf wrote:
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1970s Design Indulgence |
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Fatmangolf 
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Joined: 23 Dec 2009 Location: Middlesbrough Status: Offline Points: 8989 |
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 Posted: 15 Aug 2022 at 8:21pm |
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Thanks Graham for navigating the bureaucratic seas of poo.
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Jon
Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
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Graham Slee
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Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
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Posted: 15 Aug 2022 at 10:43pm |
 Well, since 2015 there have been a number of updates and deletions, and the set of standards I had are by now not acceptable for any new product. Therefore I have had to buy all the relevant up to date, and newly introduced standards. So far, that's 55032, 55035, 61000-4-2, 62386-1, plus three others that turned out to be only partially helpful, and by BSi pricing I'd have spent near on two grand! I estimate that by buying from the Estonian Centre For Standardisation it has cost me around £200. Additional costs were one ream of 90gsm paper and a number of ring binders, plus toner. But, if I didn't do it, and put the requirements into action, I couldn't legally sell the amplifier or its component kit. |
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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Graham Slee
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Posted: 16 Aug 2022 at 8:15am |
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Since I was a lad, the quick test to find if a transistor stage was working was to poke your finger on its base or something connected to its base. Also, when I was a lad, they'd invented nylon and polymers and such and were mixing fibres to make textiles wear longer. So we had static electricity in us, and touched transistor bases of working amplifiers and everything was hunky dory. And then, since 1995, the EU (which was planned by Adolf Hitler's economic minister during WWII - oh yes it was) decided that the input must be tested by a 600 nano-coulomb discharge with period 60ns, producing 10 amps. Yes, 10 amps is what our charged bodies were discharging into the base of those transistor stages. And if you believe that!... But you better believe it, because that's the test. IEC 61000-4-2
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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Graham Slee
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Posted: 16 Aug 2022 at 8:25am |
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Now, I reckon Estonia knows one or two things about the EU that this readership don't. So I guess they're not into the spirit of things, being right in the firing line between Russia and Germany, and knowing from past experience that those two countries conducted dodgy deals behind the scenes. So, perhaps that's why they sell "secrets" on the cheap?!
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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Graham Slee
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Posted: 16 Aug 2022 at 8:39am |
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The input stage is a BC337 transistor whose base can take 200mA max. in the positive direction.
The time constant of 60ns needs expanding such that 10 amps becomes 0.2 amps, so that's an extension of 10/0.2 = 50. The discharge resistor of the ESD gun is 330 ohms, so 50 * 330 = 16.5k!!! My experience's gut feeling says that's a big base series resistor. Perhaps up to 4k7, but 16k5?
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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Graham Slee
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Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
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Posted: 16 Aug 2022 at 10:23am |
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Now, if we use a BD139... I base max. = 0.5 amps. Then (0.5/0.2) * 16k5 = 6k6. 6k8 nearest value. But it will need more compensation because it has a wider base and that increases its capacitance. To what? Datasheets never give a straight answer. Neither do transistor SPICE subcircuits (models)!!! Models assume a particular use! The hFE is not going to be the same as in the model at 2.3mA!!! So here we're down to guesswork simply because Walther Funk started the EU...
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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Graham Slee
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Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
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Posted: 16 Aug 2022 at 11:30am |
 "Section 8.3.2. e) those contacts of connectors or other accessible parts that are ESD sensitive because of functional reasons... Rationale: Many connector ports are designed to handle high-frequency information, either analogue or digital, and therefore cannot be provided with sufficient overvoltage protection devices. In the case of analogue signals, bandpass filters may be a solution. Overvoltage protecting diodes have too much stray capacitance to be useful at the frequencies at which the EUT is designed to operate." In the case of analogue signals, bandpass filters may be a solution. Who wrote that sh*t?
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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