On Saturday, May 23, 2020 at 3:06:25 PM UTC-4, Cydrome Leader wrote:> jlarkin@highlandsniptechnology.com wrote: > > On Sat, 23 May 2020 07:45:26 +0000 (UTC), Cydrome Leader > > <presence@MUNGEpanix.com> wrote: > > > >>John Larkin <jlarkin@highland_atwork_technology.com> wrote: > >>> On Thu, 21 May 2020 04:38:47 +0000 (UTC), Cydrome Leader > >>> <presence@MUNGEpanix.com> wrote: > >>> > >>>>John Larkin <jlarkin@highland_atwork_technology.com> wrote: > >>>>> On Wed, 20 May 2020 14:07:53 -0700 (PDT), Michael Terrell > >>>>> <terrell.michael.a@gmail.com> wrote: > >>>>> > >>>>>>On Wednesday, May 20, 2020 at 12:09:51 PM UTC-4, John Larkin wrote: > >>>>>>> > >>>>>>> In our system, if you know any drawing or product part number, you > >>>>>>> automatically know all the related ones. > >>>>>>> > >>>>>>> We refer to people by their names > >>>>>> > >>>>>> > >>>>>> Some boards and modules were used in multiple product lines, so your system wouldn't have worked at Microdyne. It was a different market, requiring different methods. For instance: The 700 and 1620-base models shared a lot of boards, and the front panel/embedded controller was also used in the custom system built for NOAA to control their 100 foot dishes that track their LEO birds. Each board or model had it's own base model number, and some had over 20 versions because customers wanted different options, Some of their first products were still in use 24/7 for over 30 years at NASA, tracking deep space satellites. They had never been turned off, or repaired. > >>>>> > >>>>> We reuse boards, and assemblies, in multiple prducts. If there are > >>>>> different versions, each has its own dash number and associated BOM. > >>>>> That's standard mil practice. > >>>> > >>>>do you have to relabel parts to give them the correct (for the end user) > >>>>part number? Sometimes there's goofiness with OEMed parts and trying to > >>>>re-order them. I've gotten parts with say a different brand printed on > >>>>them. > >>> > >>> We mostly sell products that we design and build. About the only > >>> things we sell unmodified are wall-warts and a few cables, and we do > >>> give those our own part numbers. A customer orders a 12-volt wart as a > >>> model J12, and it has internal stock number 726-2012, which in turn > >>> has a list of qualified sources. > >>> > >>> We don't encourage people to repair our stuff themselves, but if they > >>> do need a part, like a transformer or connector or something, we > >>> generally give them one. > >> > >>I came across something terrible once while servicing an older machine. It > >>was "standard" octal socket/DIN mount timers or temp controllers that had > >>been tampered with by the manufacturer of the final product. The intent > >>was to render the use of off the shelf replacements inoperable. It took > >>some time to figure this out. Never seen a dick move like that before. I > >>went ahead and un-fucked the rest of the parts and rewired the sockets to > >>allow replacement of parts in the future. Sort of surprised they didn't > >>wire a NC relay contact across the power supply terminals to be honest. I > >>broke one of the controllers open to see why the new counterparts did not > >>work. > >> > >>If a customer sounds qualified, do you ever give tips in > >>troubleshooting/recalibration or anything like that? > > > > Anything they want, including schematics and advice and replacement > > loaners. But few customers can repair and recalibrate a product, > > because that generally needs a rack full of computer and test gear. We > > have sold a few test racks to customers who want to support the things > > themselves. > > > > It really annoys me when somebody charges 100x the real value for a > > replacement part that their design fried. Car dealerships sell low-end > > cars at a loss and make their profit on parts and service, like a > > $1000 door wiring harness. Kinda like ink cartriges. > > It's sort of sad wiring harnesses haven't been figured out yet. I was > reading about some maker that used some sort of soybean based wired > insulation that critters would eat up. Who the hell came up with > compostable wire or whatever the heck it was supposed to be?It's not just soybean based plastics. The military often finds out the hard way when some critter decides a material is din-din. That's why there is a fungus spec in all military electronics now. I believe they had some airplane accidents because of bio-degradation of petroleum based plastics. -- Rick C. --+ Get 1,000 miles of free Supercharging --+ Tesla referral code - https://ts.la/richard11209
why do they do this?
Started by ●May 18, 2020
Reply by ●May 23, 20202020-05-23
Reply by ●May 23, 20202020-05-23
On 2020-05-23 03:32, Cydrome Leader wrote:> Klaus Kragelund <klauskvik@hotmail.com> wrote: >> On Thursday, May 21, 2020 at 10:44:39 PM UTC+2, John Larkin wrote: >>> On Thu, 21 May 2020 14:07:29 -0400, Phil Hobbs >>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>> On 2020-05-21 13:38, John Larkin wrote: >>>>> On Tue, 19 May 2020 09:55:39 -0400, Phil Hobbs >>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>> >>>>>> On 2020-05-19 09:50, jlarkin@highlandsniptechnology.com wrote: >>>>>>> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: >>>>>>> >>>>>>>> On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: >>>>>>>>> On Mon, 18 May 2020 17:57:06 -0700 (PDT), >>>>>>>>> bloggs.fredbloggs.fred@gmail.com wrote: >>>>>>>>> >>>>>>>>>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: >>>>>>>>>>> ST makes a nice little LDO, super-low dropout with an aux Vbias >>>>>>>>>>> supply. Saves me from rolling my own with an opamp and a mosfet. >>>>>>>>>>> >>>>>>>>>>> It's an ST1L08. >>>>>>>>>>> >>>>>>>>>>> So why is the data sheet file en.DM00123507.pdf ? >>>>>>>>>> >>>>>>>>>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. >>>>>>>>> >>>>>>>>> Lying? It's all over the data sheet. It's how they get the millivolts >>>>>>>>> of dropout. I do that when I make my own super-LDOs, power an opamp >>>>>>>>> from some higher voltage and over-drive an nfet follower down to >>>>>>>>> milliohms of Rds-on. >>>>>>>>> >>>>>>>>>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. >>>>>>>>>> >>>>>>>>> >>>>>>>>> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA >>>>>>>>> would be 0.24 watts dissipated. Actually, I don't need that much >>>>>>>>> current to run a couple DRAM chips. >>>>>>>>> >>>>>>>> >>>>>>>> Not directly comparable to the ST1L08 but the Holtek HT75xx-1 >>>>>>>> series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV >>>>>>>> drop-out. 16 different fixed output voltages from 2.1V to 12V >>>>>>>> with 3% tolerance. As usual with products originating in the >>>>>>>> East, the datasheet is rather sparse about details, but I've used >>>>>>>> them and they do what I want. >>>>>>> >>>>>>> Is it stable with low ESR caps? We use polymers or ceramics mostly. >>>>>>> >>>>>>> We need so many goofy voltages that we usually buy adjustable >>>>>>> regulators for stock. The board that I'm doing now has a 24-channel >>>>>>> analog mux to BIST the power supplies, using the dreadful Xilinx >>>>>>> 1-volt XADC that's inside their FPGAs. Free and worth it. >>>>>>> >>>>>>>> >>>>>>>>> You sure are in a bad mood lately. >>>>>>>>> >>>>>>>> I've noticed that lately with some regulars here, including a few >>>>>>>> who normally exhibit decent manners. >>>>>>> >>>>>>> Well, some never show any sign of manners. They are repulsive but >>>>>>> you've got to feel sorry for them, stuck being around themselves all >>>>>>> day. >>>>>>> >>>>>>> There's a basically perfect -1 correlation between being obnoxious and >>>>>>> designing electronics. >>>>>> >>>>>> Well, now that Jim Thompson is apparently no longer with us. :( >>>>>> >>>>>> He was a bit of a statistical outlier. >>>>> >>>>> He was crabby and dismissive of people not as smart as he was, and >>>>> hostile to people that might have been smarter, but he was >>>>> occasionally helpful, and had a sense of humor, and was very brave at >>>>> the end. >>>>> >>>> >>>> When he wasn't busy accusing peoples' wives of immoral behaviour, >>>> threatening folks with lawsuits or bodily harm, or siccing the FBI on >>>> some deserving individuals. ;) >>> >>> Gosh, nobody's perfect. >>> >>>> >>>> He was probably nice enough in person--we collaborated a couple of times >>>> but never met in person or even talked on the phone together. >>>> >>>> I agree that he had guts and seems to have died very well. >>> >>> I used a version of his clever CD ignition (without his permission) as >>> a gain-switched laser driver. Nice circuit. >>> >> I talked to him a couple of times, one review on a design when I guess he was close to not being with us any more >> >> He did an ASIC gatedriver design for us, nice design, cheap like we like it >> >> Suddenly we did not hear from him again, so another ASIC designer took over at that point >> >> He did minimum dev cost design, using an old version of Pspice to simulate the design, and then had another designer lay out the chip >> >> Cheers >> >> Klaus > > Got to ask here, if I didn't years ago. How much different in behavior are > analog circuits layed out with discrete components from the final IC > itself? Let's talk pre computer simulations. For example, microwave and RF > boards are constructed different from audio circuit boards, but if you > look at a schematic, it's just a bunch of discretes wired together.BITD they had kits of prototype parts from the process they were going to use, and wired them up as breadboards. Some issues with that include: (1) temperature tracking. Discrete parts don't track well no matter what you do. Monolithic parts are a great deal better. (2) Strays. Stray inductance on-chip is nearly always negligible, and stray capacitance is probably 2 orders of magnitude less, even in a 10-um process. (Capacitance tends to go like the linear dimension.) (3) Strays (2). Mutual capacitance is very different in a monolithic design vs. a breadboard, and of course there's RFI and stuff to worry about. (It's a lot worse now than in 1970.) Despite these issues, early IC designers managed to make some pretty neat parts. Cheers Phil Hobbs Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●May 23, 20202020-05-23
On 2020-05-23, Cydrome Leader <presence@MUNGEpanix.com> wrote:> jlarkin@highlandsniptechnology.com wrote: >> On Sat, 23 May 2020 07:45:26 +0000 (UTC), Cydrome Leader >> <presence@MUNGEpanix.com> wrote: >> >>>John Larkin <jlarkin@highland_atwork_technology.com> wrote: >>>> On Thu, 21 May 2020 04:38:47 +0000 (UTC), Cydrome Leader >>>> <presence@MUNGEpanix.com> wrote: >>>> >>>>>John Larkin <jlarkin@highland_atwork_technology.com> wrote: >>>>>> On Wed, 20 May 2020 14:07:53 -0700 (PDT), Michael Terrell >>>>>> <terrell.michael.a@gmail.com> wrote: >>>>>> >>>>>>>On Wednesday, May 20, 2020 at 12:09:51 PM UTC-4, John Larkin wrote: >>>>>>>> >>>>>>>> In our system, if you know any drawing or product part number, you >>>>>>>> automatically know all the related ones. >>>>>>>> >>>>>>>> We refer to people by their names >>>>>>> >>>>>>> >>>>>>> Some boards and modules were used in multiple product lines, so your system wouldn't have worked at Microdyne. It was a different market, requiring different methods. For instance: The 700 and 1620-base models shared a lot of boards, and the front panel/embedded controller was also used in the custom system built for NOAA to control their 100 foot dishes that track their LEO birds. Each board or model had it's own base model number, and some had over 20 versions because customers wanted different options, Some of their first products were still in use 24/7 for over 30 years at NASA, tracking deep space satellites. They had never been turned off, or repaired. >>>>>> >>>>>> We reuse boards, and assemblies, in multiple prducts. If there are >>>>>> different versions, each has its own dash number and associated BOM. >>>>>> That's standard mil practice. >>>>> >>>>>do you have to relabel parts to give them the correct (for the end user) >>>>>part number? Sometimes there's goofiness with OEMed parts and trying to >>>>>re-order them. I've gotten parts with say a different brand printed on >>>>>them. >>>> >>>> We mostly sell products that we design and build. About the only >>>> things we sell unmodified are wall-warts and a few cables, and we do >>>> give those our own part numbers. A customer orders a 12-volt wart as a >>>> model J12, and it has internal stock number 726-2012, which in turn >>>> has a list of qualified sources. >>>> >>>> We don't encourage people to repair our stuff themselves, but if they >>>> do need a part, like a transformer or connector or something, we >>>> generally give them one. >>> >>>I came across something terrible once while servicing an older machine. It >>>was "standard" octal socket/DIN mount timers or temp controllers that had >>>been tampered with by the manufacturer of the final product. The intent >>>was to render the use of off the shelf replacements inoperable. It took >>>some time to figure this out. Never seen a dick move like that before. I >>>went ahead and un-fucked the rest of the parts and rewired the sockets to >>>allow replacement of parts in the future. Sort of surprised they didn't >>>wire a NC relay contact across the power supply terminals to be honest. I >>>broke one of the controllers open to see why the new counterparts did not >>>work. >>> >>>If a customer sounds qualified, do you ever give tips in >>>troubleshooting/recalibration or anything like that? >> >> Anything they want, including schematics and advice and replacement >> loaners. But few customers can repair and recalibrate a product, >> because that generally needs a rack full of computer and test gear. We >> have sold a few test racks to customers who want to support the things >> themselves. >> >> It really annoys me when somebody charges 100x the real value for a >> replacement part that their design fried. Car dealerships sell low-end >> cars at a loss and make their profit on parts and service, like a >> $1000 door wiring harness. Kinda like ink cartriges. > > It's sort of sad wiring harnesses haven't been figured out yet. I was > reading about some maker that used some sort of soybean based wired > insulation that critters would eat up. Who the hell came up with > compostable wire or whatever the heck it was supposed to be? > >>>>>> In the aircraft business, xxxxx was a drawing and xxxxx-1 was a thing, >>>>>> and xxxxx-2 was its mirror image thing. Odds and evens were mirrors, >>>>>> like wings maybe, without requiring two drawings. We don't mirror >>>>>> parts, so for us -1 and -2 are just assembly versions of some sort. >>>>> >>>>>Were there ever "funny" issues with mirror image parts, like the left part >>>>>ended up with english thread fasteners or something dumb like that? >>>> >>>> I wonder if they tapped reverse threads! >>> >>>There should be callouts, but sometimes folks have to learn the hard way. >>>I recently came some not-working test equipment that somebody tried on 208 >>>volts instead of 120 volts. Guess they forgot about that fuse block >>>voltage selector. >> >> Ancient history! It's great that most gear now runs on most any AC or >> DC voltage. > > yes and no. Most throw away type internal switching power supplies are not > serviceable and it might be hard to find replacement down the road. I > actually hit a roadblock with a plain old filament+isolation transformer. > I don't recall the generic part #, but they were a dime a dozen 100 years > ago, but not now and I can't find a suitable replacement, even if I mount > the new transformer somewhere else in the chassis. Sort of annoying. May > have to give in an call the manufacturer to see how much they want, > assuming they have spares. The 6.3 winding voltage seems too high so I > suspect shorted turns, but can't really confirm that easily.Shorted turns: look for smoke. Most likely just poor regulation... add some more load on the 6.3 and see if it gets sensible. Phil A knows mains transformers and will no-doubt be around to correct me if I am mistaken. -- Jasen.
Reply by ●May 23, 20202020-05-23
I just wanted to add to this thread... Way back, I used to fix beepers for a living. I recall that Panasonic pagers had ridiculously long part numbers. (Panasonic was never a big name in the beeper business - and I think we only carried one model - a UHF band tone-only?) Anyway, all Panasonic part numbers had the same length. But too many characters for preventing human mis-key on order entry. That is, unless the part numbers had error correction built in - they were certainly long enough for that. For example: 690004766AC6335E3E22010 would be typical. No hypens, no spaces, no breaks. And they would list them in the service manuals in one long non-alphabetized list (sorted according to component number: R1, R2, C1, U1, etc..) And the next part you might need to order would be something like: 609007664C6A635F3E22110 Stupid. Stupid. Stupid. !! Personally, I am not of fan of trying to encode product information (features, configurations, options, etc..) into part numbers. That leads to too many problems, especially if the overall numbering plan is not very, very well though-out ahead of time. Exceptions and overlaps are bound to occur, and then what? The whole system is crap. Better to have a relational database and just look it up.
Reply by ●May 23, 20202020-05-23
On Sunday, May 24, 2020 at 4:54:41 AM UTC+10, Cydrome Leader wrote:> Bill Sloman <bill.sloman@ieee.org> wrote: > > On Saturday, May 23, 2020 at 5:32:38 PM UTC+10, Cydrome Leader wrote: > >> Klaus Kragelund <klauskvik@hotmail.com> wrote: > >> > On Thursday, May 21, 2020 at 10:44:39 PM UTC+2, John Larkin wrote: > >> >> On Thu, 21 May 2020 14:07:29 -0400, Phil Hobbs > >> >> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> >> > >> >> >On 2020-05-21 13:38, John Larkin wrote: > >> >> >> On Tue, 19 May 2020 09:55:39 -0400, Phil Hobbs > >> >> >> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> >> >> > >> >> >>> On 2020-05-19 09:50, jlarkin@highlandsniptechnology.com wrote: > >> >> >>>> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: > >> >> >>>> > >> >> >>>>> On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: > >> >> >>>>>> On Mon, 18 May 2020 17:57:06 -0700 (PDT), > >> >> >>>>>> bloggs.fredbloggs.fred@gmail.com wrote: > >> >> >>>>>> > >> >> >>>>>>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: > >> >> >>>>>>>> ST makes a nice little LDO, super-low dropout with an aux Vbias > >> >> >>>>>>>> supply. Saves me from rolling my own with an opamp and a mosfet. > >> >> >>>>>>>> > >> >> >>>>>>>> It's an ST1L08. > >> >> >>>>>>>> > >> >> >>>>>>>> So why is the data sheet file en.DM00123507.pdf ? > >> >> >>>>>>> > >> >> >>>>>>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. > >> >> >>>>>> > >> >> >>>>>> Lying? It's all over the data sheet. It's how they get the millivolts > >> >> >>>>>> of dropout. I do that when I make my own super-LDOs, power an opamp > >> >> >>>>>> from some higher voltage and over-drive an nfet follower down to > >> >> >>>>>> milliohms of Rds-on. > >> >> >>>>>> > >> >> >>>>>>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. > >> >> >>>>>>> > >> >> >>>>>> > >> >> >>>>>> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA > >> >> >>>>>> would be 0.24 watts dissipated. Actually, I don't need that much > >> >> >>>>>> current to run a couple DRAM chips. > >> >> >>>>>> > >> >> >>>>> > >> >> >>>>> Not directly comparable to the ST1L08 but the Holtek HT75xx-1 > >> >> >>>>> series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV > >> >> >>>>> drop-out. 16 different fixed output voltages from 2.1V to 12V > >> >> >>>>> with 3% tolerance. As usual with products originating in the > >> >> >>>>> East, the datasheet is rather sparse about details, but I've used > >> >> >>>>> them and they do what I want. > >> >> >>>> > >> >> >>>> Is it stable with low ESR caps? We use polymers or ceramics mostly. > >> >> >>>> > >> >> >>>> We need so many goofy voltages that we usually buy adjustable > >> >> >>>> regulators for stock. The board that I'm doing now has a 24-channel > >> >> >>>> analog mux to BIST the power supplies, using the dreadful Xilinx > >> >> >>>> 1-volt XADC that's inside their FPGAs. Free and worth it. > >> >> >>>> > >> >> >>>>> > >> >> >>>>>> You sure are in a bad mood lately. > >> >> >>>>>> > >> >> >>>>> I've noticed that lately with some regulars here, including a few > >> >> >>>>> who normally exhibit decent manners. > >> >> >>>> > >> >> >>>> Well, some never show any sign of manners. They are repulsive but > >> >> >>>> you've got to feel sorry for them, stuck being around themselves all > >> >> >>>> day. > >> >> >>>> > >> >> >>>> There's a basically perfect -1 correlation between being obnoxious and > >> >> >>>> designing electronics. > >> >> >>> > >> >> >>> Well, now that Jim Thompson is apparently no longer with us. :( > >> >> >>> > >> >> >>> He was a bit of a statistical outlier. > >> >> >> > >> >> >> He was crabby and dismissive of people not as smart as he was, and > >> >> >> hostile to people that might have been smarter, but he was > >> >> >> occasionally helpful, and had a sense of humor, and was very brave at > >> >> >> the end. > >> >> > > >> >> >When he wasn't busy accusing peoples' wives of immoral behaviour, > >> >> >threatening folks with lawsuits or bodily harm, or siccing the FBI on > >> >> >some deserving individuals. ;) > >> >> > >> >> Gosh, nobody's perfect. > > > > He was imperfect enough to look remarkably like a psychopath. > > > >> >> >He was probably nice enough in person--we collaborated a couple of times > >> >> >but never met in person or even talked on the phone together. > >> >> > > >> >> >I agree that he had guts and seems to have died very well. > >> >> > >> >> I used a version of his clever CD ignition (without his permission) as > >> >> a gain-switched laser driver. Nice circuit. > >> >> > >> > I talked to him a couple of times, one review on a design when I guess he was close to not being with us any more > >> > > >> > He did an ASIC gatedriver design for us, nice design, cheap like we like it > >> > > >> > Suddenly we did not hear from him again, so another ASIC designer took over at that point > >> > > >> > He did minimum dev cost design, using an old version of Pspice to simulate the design, and then had another designer lay out the chip > >> > >> Got to ask here, if I didn't years ago. How much different in behavior are > >> analog circuits laid out with discrete components from the final IC > >> itself? > > > > My impression is integrated circuit designs don't look much like discrete component designs. > > > > Lot's more current sources, and many fewer resistors for a start. At high frequencies, the fact that the connections are lot shorter (and less inductive) makes a big difference. Bob Widlar and Barry Gilbert were famously good at exploiting the advantages these sorts of difference offer. > > > >> Let's talk pre computer simulations. For example, microwave and RF > >> boards are constructed different from audio circuit boards, but if you > >> look at a schematic, it's just a bunch of discretes wired together. > > > > If you look at the printed circuit boards, microwave and RF boards are > > constructed with the critical connections laid out as constant impedance > > transmission lines routed over (or between) solid ground planes (mostly > > buried in multilayer boards). Buried ground planes do show up in some > > audio circuits - they do a good job of shielding sensitive bits from > > noise radiated from the higher current bits, and any digital signals > > running around - but you can get by without them. > > > > Looking at the schematic isn't all that educational - essentially it's a > > way of representing the net-list (which pins on which components are > > connected to which other pins). It leaves out stray capacitances, lead > > inductances, mutual inductances between leads, heat dissipation, > > component dimensions and the rest of the stuff that constrains printed > > circuit layout. > > so how did they come up with designs that worked? Take the first op amps > for example. The behavior of the silicon isn't going to match a breadboard > with some parts on it. Was it just a completely iterative process back in > the day to get anything to work? > > > Back when I was designing circuits, the schematic got passed to the > > drafting shop with several pages of notes on how it was going to have to > > be laid out. > > > > The good layout draftsmen didn't need much, but they weren't all good. > > Once a printed circuit manufacturer didn't like my board stack-up - they > > feared that the board would warp - and the draftsman okayed their > > version. > > > > A whole lot of constant impedance transmission ended up with with the > > wrong impedance. It took us a couple weeks to wake up. > > Was any of this salvagable, or was it on to rev b?It got sort of cobbled into sort of working with lot's of sub-minature Filotex coaxial cable (about 1.1 mm OD IIRR). The other thing that messed up the board was Gigabit Logic's failure to put the input capacitance of their logic on the data sheet - on rev b every last clock input had it's own private driver. The other thing that messed it up was that it was supposed to clock a long 100k ECL synchronous counter at 200MHz, which would have been doable with careful design - as I had spelled out in the specification. The guy who did the detailed design of the board was entirely capable of managing that, but was also smart enough to know that the machine was never going to get into production - it didn't - and didn't bother. If we'd done a design review on the schematic before releasing for printed circuit layout I might well have caught it, but our idiot project manager didn't want to slow down the process by the day that would have taken. We had a similar drop-off on the digital signal process board which took much longer to find (but was much easier to cope with when it did get noticed). I was sufficiently peeved by the time the project got cancelled - after three years work when the machine was working - to take away three years worth of weekly reports. About fifteen years later I got around to scanning them. You could read them here http://sophia-elektronica.com/At_Cambridge.html if you were a glutton for punishment. The reports are accessible - in one year chunks - at the bottom of the page. There's also a link there to a document that fills in some of the immediate background. It will make more sense if your read my "short history of voltage contrast" link at the top of the page, which ends with links to same set of documents.> Anyone have stories of most expensive screw ups with board design or > assemble?I think we were paid about a thousand UK pounds for the board that got screwed up - it was a six layer board, with the two outer layers made of isocyanate bonded Teflon (PTFE) cloth, rather than than the standard epoxy-bonded glass fibre. The printed circuit house had had to buy in an expensive chunk of the PTFE based board material before they could make the board, and didn't expect to sell any of it to anybody else. We then stuck about five hundred UK pounds worth of GaAs integrated circuits from GigaBit Logic onto the board. That meant that wed spent more than two thousand US dollars on the board. It was a triple extended Eurocard, which was pretty big for a rack-mounted board plugging into a backplane. -- Bill Sloman, Sydney
Reply by ●May 24, 20202020-05-24
On Sunday, May 24, 2020 at 5:45:31 AM UTC+10, Ricketty C wrote:> On Saturday, May 23, 2020 at 3:06:25 PM UTC-4, Cydrome Leader wrote: > > jlarkin@highlandsniptechnology.com wrote: > > > On Sat, 23 May 2020 07:45:26 +0000 (UTC), Cydrome Leader > > > <presence@MUNGEpanix.com> wrote: > > > > > >>John Larkin <jlarkin@highland_atwork_technology.com> wrote: > > >>> On Thu, 21 May 2020 04:38:47 +0000 (UTC), Cydrome Leader > > >>> <presence@MUNGEpanix.com> wrote: > > >>> > > >>>>John Larkin <jlarkin@highland_atwork_technology.com> wrote: > > >>>>> On Wed, 20 May 2020 14:07:53 -0700 (PDT), Michael Terrell > > >>>>> <terrell.michael.a@gmail.com> wrote: > > >>>>> > > >>>>>>On Wednesday, May 20, 2020 at 12:09:51 PM UTC-4, John Larkin wrote: > > >>>>>>> > > >>>>>>> In our system, if you know any drawing or product part number, you > > >>>>>>> automatically know all the related ones. > > >>>>>>> > > >>>>>>> We refer to people by their names > > >>>>>> > > >>>>>> > > >>>>>> Some boards and modules were used in multiple product lines, so your system wouldn't have worked at Microdyne. It was a different market, requiring different methods. For instance: The 700 and 1620-base models shared a lot of boards, and the front panel/embedded controller was also used in the custom system built for NOAA to control their 100 foot dishes that track their LEO birds. Each board or model had it's own base model number, and some had over 20 versions because customers wanted different options, Some of their first products were still in use 24/7 for over 30 years at NASA, tracking deep space satellites. They had never been turned off, or repaired. > > >>>>> > > >>>>> We reuse boards, and assemblies, in multiple prducts. If there are > > >>>>> different versions, each has its own dash number and associated BOM. > > >>>>> That's standard mil practice. > > >>>> > > >>>>do you have to relabel parts to give them the correct (for the end user) > > >>>>part number? Sometimes there's goofiness with OEMed parts and trying to > > >>>>re-order them. I've gotten parts with say a different brand printed on > > >>>>them. > > >>> > > >>> We mostly sell products that we design and build. About the only > > >>> things we sell unmodified are wall-warts and a few cables, and we do > > >>> give those our own part numbers. A customer orders a 12-volt wart as a > > >>> model J12, and it has internal stock number 726-2012, which in turn > > >>> has a list of qualified sources. > > >>> > > >>> We don't encourage people to repair our stuff themselves, but if they > > >>> do need a part, like a transformer or connector or something, we > > >>> generally give them one. > > >> > > >>I came across something terrible once while servicing an older machine. It > > >>was "standard" octal socket/DIN mount timers or temp controllers that had > > >>been tampered with by the manufacturer of the final product. The intent > > >>was to render the use of off the shelf replacements inoperable. It took > > >>some time to figure this out. Never seen a dick move like that before. I > > >>went ahead and un-fucked the rest of the parts and rewired the sockets to > > >>allow replacement of parts in the future. Sort of surprised they didn't > > >>wire a NC relay contact across the power supply terminals to be honest. I > > >>broke one of the controllers open to see why the new counterparts did not > > >>work. > > >> > > >>If a customer sounds qualified, do you ever give tips in > > >>troubleshooting/recalibration or anything like that? > > > > > > Anything they want, including schematics and advice and replacement > > > loaners. But few customers can repair and recalibrate a product, > > > because that generally needs a rack full of computer and test gear. We > > > have sold a few test racks to customers who want to support the things > > > themselves. > > > > > > It really annoys me when somebody charges 100x the real value for a > > > replacement part that their design fried. Car dealerships sell low-end > > > cars at a loss and make their profit on parts and service, like a > > > $1000 door wiring harness. Kinda like ink cartriges. > > > > It's sort of sad wiring harnesses haven't been figured out yet. I was > > reading about some maker that used some sort of soybean based wired > > insulation that critters would eat up. Who the hell came up with > > compostable wire or whatever the heck it was supposed to be? > > It's not just soybean based plastics. The military often finds out the hard way when some critter decides a material is din-din. That's why there is a fungus spec in all military electronics now. I believe they had some airplane accidents because of bio-degradation of petroleum based plastics.One of the more famous examples was the WW2 Mosquito figher-bomber, which made brilliant use of urea-formaldehyde bonded layers of wood. It was extreme;y effective in the temperate zone, but fungi got at the structure in the tropics, and the planes exhibited a nasty habit of coming apart in midair in those theatres. -- Bill Sloman, Sydney
Reply by ●May 24, 20202020-05-24
On Saturday, May 23, 2020 at 9:32:38 AM UTC+2, Cydrome Leader wrote:> Klaus Kragelund <klauskvik@hotmail.com> wrote: > > On Thursday, May 21, 2020 at 10:44:39 PM UTC+2, John Larkin wrote: > >> On Thu, 21 May 2020 14:07:29 -0400, Phil Hobbs > >> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> > >> >On 2020-05-21 13:38, John Larkin wrote: > >> >> On Tue, 19 May 2020 09:55:39 -0400, Phil Hobbs > >> >> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> >> > >> >>> On 2020-05-19 09:50, jlarkin@highlandsniptechnology.com wrote: > >> >>>> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: > >> >>>> > >> >>>>> On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: > >> >>>>>> On Mon, 18 May 2020 17:57:06 -0700 (PDT), > >> >>>>>> bloggs.fredbloggs.fred@gmail.com wrote: > >> >>>>>> > >> >>>>>>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: > >> >>>>>>>> ST makes a nice little LDO, super-low dropout with an aux Vbias > >> >>>>>>>> supply. Saves me from rolling my own with an opamp and a mosfet. > >> >>>>>>>> > >> >>>>>>>> It's an ST1L08. > >> >>>>>>>> > >> >>>>>>>> So why is the data sheet file en.DM00123507.pdf ? > >> >>>>>>> > >> >>>>>>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. > >> >>>>>> > >> >>>>>> Lying? It's all over the data sheet. It's how they get the millivolts > >> >>>>>> of dropout. I do that when I make my own super-LDOs, power an opamp > >> >>>>>> from some higher voltage and over-drive an nfet follower down to > >> >>>>>> milliohms of Rds-on. > >> >>>>>> > >> >>>>>>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. > >> >>>>>>> > >> >>>>>> > >> >>>>>> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA > >> >>>>>> would be 0.24 watts dissipated. Actually, I don't need that much > >> >>>>>> current to run a couple DRAM chips. > >> >>>>>> > >> >>>>> > >> >>>>> Not directly comparable to the ST1L08 but the Holtek HT75xx-1 > >> >>>>> series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV > >> >>>>> drop-out. 16 different fixed output voltages from 2.1V to 12V > >> >>>>> with 3% tolerance. As usual with products originating in the > >> >>>>> East, the datasheet is rather sparse about details, but I've used > >> >>>>> them and they do what I want. > >> >>>> > >> >>>> Is it stable with low ESR caps? We use polymers or ceramics mostly. > >> >>>> > >> >>>> We need so many goofy voltages that we usually buy adjustable > >> >>>> regulators for stock. The board that I'm doing now has a 24-channel > >> >>>> analog mux to BIST the power supplies, using the dreadful Xilinx > >> >>>> 1-volt XADC that's inside their FPGAs. Free and worth it. > >> >>>> > >> >>>>> > >> >>>>>> You sure are in a bad mood lately. > >> >>>>>> > >> >>>>> I've noticed that lately with some regulars here, including a few > >> >>>>> who normally exhibit decent manners. > >> >>>> > >> >>>> Well, some never show any sign of manners. They are repulsive but > >> >>>> you've got to feel sorry for them, stuck being around themselves all > >> >>>> day. > >> >>>> > >> >>>> There's a basically perfect -1 correlation between being obnoxious and > >> >>>> designing electronics. > >> >>> > >> >>> Well, now that Jim Thompson is apparently no longer with us. :( > >> >>> > >> >>> He was a bit of a statistical outlier. > >> >> > >> >> He was crabby and dismissive of people not as smart as he was, and > >> >> hostile to people that might have been smarter, but he was > >> >> occasionally helpful, and had a sense of humor, and was very brave at > >> >> the end. > >> >> > >> > > >> >When he wasn't busy accusing peoples' wives of immoral behaviour, > >> >threatening folks with lawsuits or bodily harm, or siccing the FBI on > >> >some deserving individuals. ;) > >> > >> Gosh, nobody's perfect. > >> > >> > > >> >He was probably nice enough in person--we collaborated a couple of times > >> >but never met in person or even talked on the phone together. > >> > > >> >I agree that he had guts and seems to have died very well. > >> > >> I used a version of his clever CD ignition (without his permission) as > >> a gain-switched laser driver. Nice circuit. > >> > > I talked to him a couple of times, one review on a design when I guess he was close to not being with us any more > > > > He did an ASIC gatedriver design for us, nice design, cheap like we like it > > > > Suddenly we did not hear from him again, so another ASIC designer took over at that point > > > > He did minimum dev cost design, using an old version of Pspice to simulate the design, and then had another designer lay out the chip > > > > Cheers > > > > Klaus > > Got to ask here, if I didn't years ago. How much different in behavior are > analog circuits layed out with discrete components from the final IC > itself? Let's talk pre computer simulations. For example, microwave and RF > boards are constructed different from audio circuit boards, but if you > look at a schematic, it's just a bunch of discretes wired together.It can be very simelar In our case, to keep NRE low, we needed to use almost only predefined blocks. When you team up with a fab, they supply all datasheets and simulation models for standard blocks. So, opamps, comparators, digital blocks, voltage references, PWM circuits and individual transistors The blocks are proven in the technology and simulation vs real life is 100% spot on. The tools are very expensive, but they model the chip to every detail. Thus, experienced ASIC designers never need to do new revisions. If you wander off, and do custom blocks, it gets a lot more expensive So you if you find a discrete opamp that matches your ASIC block, so can do proof of concept in discrete design If not, simulations is the way forward And by the way, prototypes with MOSIS is very cheap, you just need to wait a loooooong time from design to the first chips comes in Cheers Klaus
Reply by ●May 24, 20202020-05-24
Bill Sloman <bill.sloman@ieee.org> wrote:> On Sunday, May 24, 2020 at 4:54:41 AM UTC+10, Cydrome Leader wrote: >> Bill Sloman <bill.sloman@ieee.org> wrote: >> > On Saturday, May 23, 2020 at 5:32:38 PM UTC+10, Cydrome Leader wrote: >> >> Klaus Kragelund <klauskvik@hotmail.com> wrote: >> >> > On Thursday, May 21, 2020 at 10:44:39 PM UTC+2, John Larkin wrote: >> >> >> On Thu, 21 May 2020 14:07:29 -0400, Phil Hobbs >> >> >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >> >> >> >> >> >On 2020-05-21 13:38, John Larkin wrote: >> >> >> >> On Tue, 19 May 2020 09:55:39 -0400, Phil Hobbs >> >> >> >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >> >> >> >> >> >> >>> On 2020-05-19 09:50, jlarkin@highlandsniptechnology.com wrote: >> >> >> >>>> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: >> >> >> >>>> >> >> >> >>>>> On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: >> >> >> >>>>>> On Mon, 18 May 2020 17:57:06 -0700 (PDT), >> >> >> >>>>>> bloggs.fredbloggs.fred@gmail.com wrote: >> >> >> >>>>>> >> >> >> >>>>>>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: >> >> >> >>>>>>>> ST makes a nice little LDO, super-low dropout with an aux Vbias >> >> >> >>>>>>>> supply. Saves me from rolling my own with an opamp and a mosfet. >> >> >> >>>>>>>> >> >> >> >>>>>>>> It's an ST1L08. >> >> >> >>>>>>>> >> >> >> >>>>>>>> So why is the data sheet file en.DM00123507.pdf ? >> >> >> >>>>>>> >> >> >> >>>>>>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. >> >> >> >>>>>> >> >> >> >>>>>> Lying? It's all over the data sheet. It's how they get the millivolts >> >> >> >>>>>> of dropout. I do that when I make my own super-LDOs, power an opamp >> >> >> >>>>>> from some higher voltage and over-drive an nfet follower down to >> >> >> >>>>>> milliohms of Rds-on. >> >> >> >>>>>> >> >> >> >>>>>>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. >> >> >> >>>>>>> >> >> >> >>>>>> >> >> >> >>>>>> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA >> >> >> >>>>>> would be 0.24 watts dissipated. Actually, I don't need that much >> >> >> >>>>>> current to run a couple DRAM chips. >> >> >> >>>>>> >> >> >> >>>>> >> >> >> >>>>> Not directly comparable to the ST1L08 but the Holtek HT75xx-1 >> >> >> >>>>> series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV >> >> >> >>>>> drop-out. 16 different fixed output voltages from 2.1V to 12V >> >> >> >>>>> with 3% tolerance. As usual with products originating in the >> >> >> >>>>> East, the datasheet is rather sparse about details, but I've used >> >> >> >>>>> them and they do what I want. >> >> >> >>>> >> >> >> >>>> Is it stable with low ESR caps? We use polymers or ceramics mostly. >> >> >> >>>> >> >> >> >>>> We need so many goofy voltages that we usually buy adjustable >> >> >> >>>> regulators for stock. The board that I'm doing now has a 24-channel >> >> >> >>>> analog mux to BIST the power supplies, using the dreadful Xilinx >> >> >> >>>> 1-volt XADC that's inside their FPGAs. Free and worth it. >> >> >> >>>> >> >> >> >>>>> >> >> >> >>>>>> You sure are in a bad mood lately. >> >> >> >>>>>> >> >> >> >>>>> I've noticed that lately with some regulars here, including a few >> >> >> >>>>> who normally exhibit decent manners. >> >> >> >>>> >> >> >> >>>> Well, some never show any sign of manners. They are repulsive but >> >> >> >>>> you've got to feel sorry for them, stuck being around themselves all >> >> >> >>>> day. >> >> >> >>>> >> >> >> >>>> There's a basically perfect -1 correlation between being obnoxious and >> >> >> >>>> designing electronics. >> >> >> >>> >> >> >> >>> Well, now that Jim Thompson is apparently no longer with us. :( >> >> >> >>> >> >> >> >>> He was a bit of a statistical outlier. >> >> >> >> >> >> >> >> He was crabby and dismissive of people not as smart as he was, and >> >> >> >> hostile to people that might have been smarter, but he was >> >> >> >> occasionally helpful, and had a sense of humor, and was very brave at >> >> >> >> the end. >> >> >> > >> >> >> >When he wasn't busy accusing peoples' wives of immoral behaviour, >> >> >> >threatening folks with lawsuits or bodily harm, or siccing the FBI on >> >> >> >some deserving individuals. ;) >> >> >> >> >> >> Gosh, nobody's perfect. >> > >> > He was imperfect enough to look remarkably like a psychopath. >> > >> >> >> >He was probably nice enough in person--we collaborated a couple of times >> >> >> >but never met in person or even talked on the phone together. >> >> >> > >> >> >> >I agree that he had guts and seems to have died very well. >> >> >> >> >> >> I used a version of his clever CD ignition (without his permission) as >> >> >> a gain-switched laser driver. Nice circuit. >> >> >> >> >> > I talked to him a couple of times, one review on a design when I guess he was close to not being with us any more >> >> > >> >> > He did an ASIC gatedriver design for us, nice design, cheap like we like it >> >> > >> >> > Suddenly we did not hear from him again, so another ASIC designer took over at that point >> >> > >> >> > He did minimum dev cost design, using an old version of Pspice to simulate the design, and then had another designer lay out the chip >> >> >> >> Got to ask here, if I didn't years ago. How much different in behavior are >> >> analog circuits laid out with discrete components from the final IC >> >> itself? >> > >> > My impression is integrated circuit designs don't look much like discrete component designs. >> > >> > Lot's more current sources, and many fewer resistors for a start. At high frequencies, the fact that the connections are lot shorter (and less inductive) makes a big difference. Bob Widlar and Barry Gilbert were famously good at exploiting the advantages these sorts of difference offer. >> > >> >> Let's talk pre computer simulations. For example, microwave and RF >> >> boards are constructed different from audio circuit boards, but if you >> >> look at a schematic, it's just a bunch of discretes wired together. >> > >> > If you look at the printed circuit boards, microwave and RF boards are >> > constructed with the critical connections laid out as constant impedance >> > transmission lines routed over (or between) solid ground planes (mostly >> > buried in multilayer boards). Buried ground planes do show up in some >> > audio circuits - they do a good job of shielding sensitive bits from >> > noise radiated from the higher current bits, and any digital signals >> > running around - but you can get by without them. >> > >> > Looking at the schematic isn't all that educational - essentially it's a >> > way of representing the net-list (which pins on which components are >> > connected to which other pins). It leaves out stray capacitances, lead >> > inductances, mutual inductances between leads, heat dissipation, >> > component dimensions and the rest of the stuff that constrains printed >> > circuit layout. >> >> so how did they come up with designs that worked? Take the first op amps >> for example. The behavior of the silicon isn't going to match a breadboard >> with some parts on it. Was it just a completely iterative process back in >> the day to get anything to work? >> >> > Back when I was designing circuits, the schematic got passed to the >> > drafting shop with several pages of notes on how it was going to have to >> > be laid out. >> > >> > The good layout draftsmen didn't need much, but they weren't all good. >> > Once a printed circuit manufacturer didn't like my board stack-up - they >> > feared that the board would warp - and the draftsman okayed their >> > version. >> > >> > A whole lot of constant impedance transmission ended up with with the >> > wrong impedance. It took us a couple weeks to wake up. >> >> Was any of this salvagable, or was it on to rev b? > > It got sort of cobbled into sort of working with lot's of sub-minature Filotex coaxial cable (about 1.1 mm OD IIRR). The other thing that messed up the board was Gigabit Logic's failure to put the input capacitance of their logic on the data sheet - on rev b every last clock input had it's own private driver. > > The other thing that messed it up was that it was supposed to clock a long 100k ECL synchronous counter at 200MHz, which would have been doable with careful design - as I had spelled out in the specification. The guy who did the detailed design of the board was entirely capable of managing that, but was also smart enough to know that the machine was never going to get into production - it didn't - and didn't bother. > > If we'd done a design review on the schematic before releasing for printed circuit layout I might well have caught it, but our idiot project manager didn't want to slow down the process by the day that would have taken. > > We had a similar drop-off on the digital signal process board which took much longer to find (but was much easier to cope with when it did get noticed). > > I was sufficiently peeved by the time the project got cancelled - after three years work when the machine was working - to take away three years worth of weekly reports. About fifteen years later I got around to scanning them. > > You could read them here > > http://sophia-elektronica.com/At_Cambridge.htmlInteresting read- nearly completed with 1989. Got some more observations questions, if you don't mind. How were low production SMD boards populated back then? Semi-manual or automated? The references to 17A -5.2v ECL boards was amusing too. I was reading somewhere that some folks didn't use convention regulated power supplies for ECL boards as the load never changed. Is there any truth to this? What were the special mu-metal tanks and covers for? The 0.4hz cursor update speed on a display is funny, in comparison for the hunt for 100ps timing on other parts of the device. There was reference to some type of glue logic (7400 series?) LS vs HC where the HC series stuff used too much power. Wasn't the CMOS stuff supposed to be lower power, or was this only below certain frequencies? I recall some other boards where the power hungry "S" series stuff was still used in place of LS series parts.> if you were a glutton for punishment. The reports are accessible- in> one year chunks - at the bottom of the page. There's also a link there > to a document that fills in some of the immediate background. > > It will make more sense if your read my "short history of voltage > contrast" link at the top of the page, which ends with links to same set > of documents. > >> Anyone have stories of most expensive screw ups with board design or >> assemble? > > I think we were paid about a thousand UK pounds for the board that got > screwed up - it was a six layer board, with the two outer layers made of > isocyanate bonded Teflon (PTFE) cloth, rather than than the standard > epoxy-bonded glass fibre. The printed circuit house had had to buy in an > expensive chunk of the PTFE based board material before they could make > the board, and didn't expect to sell any of it to anybody else.I wonder what the board houses yield was, 0.008" traces is still pretty small. How large were these boards? The AMD 0.1% yield on another component was pretty funny too. There was an issue at work where a process (not product) had a 5% pass rate. My joke was the systems that passed validation were simply done right, by accident.> We then stuck about five hundred UK pounds worth of GaAs integrated > circuits from GigaBit Logic onto the board. That meant that wed spent > more than two thousand US dollars on the board. It was a triple extended > Eurocard, which was pretty big for a rack-mounted board plugging into a > backplane.OK, so triple extended euro card was the size of the fancy board? Need to look that up. How hard would all this be to contruct using modern technology? I find it fascinating that we still fall back to plain silicon and don't require exotic materials for speeds you were dealing with. Is this simply because components can be made smaller now? The spec sheets for USB3 transceivers have many values in uS and even nS, way faster than even fancy chips back then. They're plain old silicon and work fine on even crappy circuit boards, and cost nothing. It's quite amazing.
Reply by ●May 24, 20202020-05-24
Klaus Kragelund <klauskvik@hotmail.com> wrote:> On Saturday, May 23, 2020 at 9:32:38 AM UTC+2, Cydrome Leader wrote: >> Klaus Kragelund <klauskvik@hotmail.com> wrote: >> > On Thursday, May 21, 2020 at 10:44:39 PM UTC+2, John Larkin wrote: >> >> On Thu, 21 May 2020 14:07:29 -0400, Phil Hobbs >> >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >> >> >> >On 2020-05-21 13:38, John Larkin wrote: >> >> >> On Tue, 19 May 2020 09:55:39 -0400, Phil Hobbs >> >> >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >> >> >> >> >>> On 2020-05-19 09:50, jlarkin@highlandsniptechnology.com wrote: >> >> >>>> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: >> >> >>>> >> >> >>>>> On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: >> >> >>>>>> On Mon, 18 May 2020 17:57:06 -0700 (PDT), >> >> >>>>>> bloggs.fredbloggs.fred@gmail.com wrote: >> >> >>>>>> >> >> >>>>>>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: >> >> >>>>>>>> ST makes a nice little LDO, super-low dropout with an aux Vbias >> >> >>>>>>>> supply. Saves me from rolling my own with an opamp and a mosfet. >> >> >>>>>>>> >> >> >>>>>>>> It's an ST1L08. >> >> >>>>>>>> >> >> >>>>>>>> So why is the data sheet file en.DM00123507.pdf ? >> >> >>>>>>> >> >> >>>>>>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. >> >> >>>>>> >> >> >>>>>> Lying? It's all over the data sheet. It's how they get the millivolts >> >> >>>>>> of dropout. I do that when I make my own super-LDOs, power an opamp >> >> >>>>>> from some higher voltage and over-drive an nfet follower down to >> >> >>>>>> milliohms of Rds-on. >> >> >>>>>> >> >> >>>>>>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. >> >> >>>>>>> >> >> >>>>>> >> >> >>>>>> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA >> >> >>>>>> would be 0.24 watts dissipated. Actually, I don't need that much >> >> >>>>>> current to run a couple DRAM chips. >> >> >>>>>> >> >> >>>>> >> >> >>>>> Not directly comparable to the ST1L08 but the Holtek HT75xx-1 >> >> >>>>> series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV >> >> >>>>> drop-out. 16 different fixed output voltages from 2.1V to 12V >> >> >>>>> with 3% tolerance. As usual with products originating in the >> >> >>>>> East, the datasheet is rather sparse about details, but I've used >> >> >>>>> them and they do what I want. >> >> >>>> >> >> >>>> Is it stable with low ESR caps? We use polymers or ceramics mostly. >> >> >>>> >> >> >>>> We need so many goofy voltages that we usually buy adjustable >> >> >>>> regulators for stock. The board that I'm doing now has a 24-channel >> >> >>>> analog mux to BIST the power supplies, using the dreadful Xilinx >> >> >>>> 1-volt XADC that's inside their FPGAs. Free and worth it. >> >> >>>> >> >> >>>>> >> >> >>>>>> You sure are in a bad mood lately. >> >> >>>>>> >> >> >>>>> I've noticed that lately with some regulars here, including a few >> >> >>>>> who normally exhibit decent manners. >> >> >>>> >> >> >>>> Well, some never show any sign of manners. They are repulsive but >> >> >>>> you've got to feel sorry for them, stuck being around themselves all >> >> >>>> day. >> >> >>>> >> >> >>>> There's a basically perfect -1 correlation between being obnoxious and >> >> >>>> designing electronics. >> >> >>> >> >> >>> Well, now that Jim Thompson is apparently no longer with us. :( >> >> >>> >> >> >>> He was a bit of a statistical outlier. >> >> >> >> >> >> He was crabby and dismissive of people not as smart as he was, and >> >> >> hostile to people that might have been smarter, but he was >> >> >> occasionally helpful, and had a sense of humor, and was very brave at >> >> >> the end. >> >> >> >> >> > >> >> >When he wasn't busy accusing peoples' wives of immoral behaviour, >> >> >threatening folks with lawsuits or bodily harm, or siccing the FBI on >> >> >some deserving individuals. ;) >> >> >> >> Gosh, nobody's perfect. >> >> >> >> > >> >> >He was probably nice enough in person--we collaborated a couple of times >> >> >but never met in person or even talked on the phone together. >> >> > >> >> >I agree that he had guts and seems to have died very well. >> >> >> >> I used a version of his clever CD ignition (without his permission) as >> >> a gain-switched laser driver. Nice circuit. >> >> >> > I talked to him a couple of times, one review on a design when I guess he was close to not being with us any more >> > >> > He did an ASIC gatedriver design for us, nice design, cheap like we like it >> > >> > Suddenly we did not hear from him again, so another ASIC designer took over at that point >> > >> > He did minimum dev cost design, using an old version of Pspice to simulate the design, and then had another designer lay out the chip >> > >> > Cheers >> > >> > Klaus >> >> Got to ask here, if I didn't years ago. How much different in behavior are >> analog circuits layed out with discrete components from the final IC >> itself? Let's talk pre computer simulations. For example, microwave and RF >> boards are constructed different from audio circuit boards, but if you >> look at a schematic, it's just a bunch of discretes wired together. > > It can be very simelar > > In our case, to keep NRE low, we needed to use almost only predefined blocks. When you team up with a fab, they supply all datasheets and simulation models for standard blocks. So, opamps, comparators, digital blocks, voltage references, PWM circuits and individual transistors > > The blocks are proven in the technology and simulation vs real life is 100% spot on. The tools are very expensive, but they model the chip to every detail. Thus, experienced ASIC designers never need to do new revisions. > > If you wander off, and do custom blocks, it gets a lot more expensive > > So you if you find a discrete opamp that matches your ASIC block, so can do proof of concept in discrete design > If not, simulations is the way forward > > And by the way, prototypes with MOSIS is very cheap, you just need to wait a loooooong time from design to the first chips comes in > > > Cheers > > KlausHmm. What about equivalent, full sized components? Take the example the 74LS00 nand gate, TI has a schematic https://html.alldatasheet.com/html-pdf/27361/TI/74LS00N/73/3/74LS00N.html Are there equivalent transistors and diodes used in that schematic I can run out and buy, to make an as close to 100% electrically compatible, drop in replacement? I'm not even sure what the first transitor is with A and B inputs is even called. What is it?
Reply by ●May 24, 20202020-05-24
Jasen Betts <jasen@xnet.co.nz> wrote:> On 2020-05-23, Cydrome Leader <presence@MUNGEpanix.com> wrote: >> jlarkin@highlandsniptechnology.com wrote: >>> On Sat, 23 May 2020 07:45:26 +0000 (UTC), Cydrome Leader >>> <presence@MUNGEpanix.com> wrote: >>> >>>>John Larkin <jlarkin@highland_atwork_technology.com> wrote: >>>>> On Thu, 21 May 2020 04:38:47 +0000 (UTC), Cydrome Leader >>>>> <presence@MUNGEpanix.com> wrote: >>>>> >>>>>>John Larkin <jlarkin@highland_atwork_technology.com> wrote: >>>>>>> On Wed, 20 May 2020 14:07:53 -0700 (PDT), Michael Terrell >>>>>>> <terrell.michael.a@gmail.com> wrote: >>>>>>> >>>>>>>>On Wednesday, May 20, 2020 at 12:09:51 PM UTC-4, John Larkin wrote: >>>>>>>>> >>>>>>>>> In our system, if you know any drawing or product part number, you >>>>>>>>> automatically know all the related ones. >>>>>>>>> >>>>>>>>> We refer to people by their names >>>>>>>> >>>>>>>> >>>>>>>> Some boards and modules were used in multiple product lines, so your system wouldn't have worked at Microdyne. It was a different market, requiring different methods. For instance: The 700 and 1620-base models shared a lot of boards, and the front panel/embedded controller was also used in the custom system built for NOAA to control their 100 foot dishes that track their LEO birds. Each board or model had it's own base model number, and some had over 20 versions because customers wanted different options, Some of their first products were still in use 24/7 for over 30 years at NASA, tracking deep space satellites. They had never been turned off, or repaired. >>>>>>> >>>>>>> We reuse boards, and assemblies, in multiple prducts. If there are >>>>>>> different versions, each has its own dash number and associated BOM. >>>>>>> That's standard mil practice. >>>>>> >>>>>>do you have to relabel parts to give them the correct (for the end user) >>>>>>part number? Sometimes there's goofiness with OEMed parts and trying to >>>>>>re-order them. I've gotten parts with say a different brand printed on >>>>>>them. >>>>> >>>>> We mostly sell products that we design and build. About the only >>>>> things we sell unmodified are wall-warts and a few cables, and we do >>>>> give those our own part numbers. A customer orders a 12-volt wart as a >>>>> model J12, and it has internal stock number 726-2012, which in turn >>>>> has a list of qualified sources. >>>>> >>>>> We don't encourage people to repair our stuff themselves, but if they >>>>> do need a part, like a transformer or connector or something, we >>>>> generally give them one. >>>> >>>>I came across something terrible once while servicing an older machine. It >>>>was "standard" octal socket/DIN mount timers or temp controllers that had >>>>been tampered with by the manufacturer of the final product. The intent >>>>was to render the use of off the shelf replacements inoperable. It took >>>>some time to figure this out. Never seen a dick move like that before. I >>>>went ahead and un-fucked the rest of the parts and rewired the sockets to >>>>allow replacement of parts in the future. Sort of surprised they didn't >>>>wire a NC relay contact across the power supply terminals to be honest. I >>>>broke one of the controllers open to see why the new counterparts did not >>>>work. >>>> >>>>If a customer sounds qualified, do you ever give tips in >>>>troubleshooting/recalibration or anything like that? >>> >>> Anything they want, including schematics and advice and replacement >>> loaners. But few customers can repair and recalibrate a product, >>> because that generally needs a rack full of computer and test gear. We >>> have sold a few test racks to customers who want to support the things >>> themselves. >>> >>> It really annoys me when somebody charges 100x the real value for a >>> replacement part that their design fried. Car dealerships sell low-end >>> cars at a loss and make their profit on parts and service, like a >>> $1000 door wiring harness. Kinda like ink cartriges. >> >> It's sort of sad wiring harnesses haven't been figured out yet. I was >> reading about some maker that used some sort of soybean based wired >> insulation that critters would eat up. Who the hell came up with >> compostable wire or whatever the heck it was supposed to be? >> >>>>>>> In the aircraft business, xxxxx was a drawing and xxxxx-1 was a thing, >>>>>>> and xxxxx-2 was its mirror image thing. Odds and evens were mirrors, >>>>>>> like wings maybe, without requiring two drawings. We don't mirror >>>>>>> parts, so for us -1 and -2 are just assembly versions of some sort. >>>>>> >>>>>>Were there ever "funny" issues with mirror image parts, like the left part >>>>>>ended up with english thread fasteners or something dumb like that? >>>>> >>>>> I wonder if they tapped reverse threads! >>>> >>>>There should be callouts, but sometimes folks have to learn the hard way. >>>>I recently came some not-working test equipment that somebody tried on 208 >>>>volts instead of 120 volts. Guess they forgot about that fuse block >>>>voltage selector. >>> >>> Ancient history! It's great that most gear now runs on most any AC or >>> DC voltage. >> >> yes and no. Most throw away type internal switching power supplies are not >> serviceable and it might be hard to find replacement down the road. I >> actually hit a roadblock with a plain old filament+isolation transformer. >> I don't recall the generic part #, but they were a dime a dozen 100 years >> ago, but not now and I can't find a suitable replacement, even if I mount >> the new transformer somewhere else in the chassis. Sort of annoying. May >> have to give in an call the manufacturer to see how much they want, >> assuming they have spares. The 6.3 winding voltage seems too high so I >> suspect shorted turns, but can't really confirm that easily. > > Shorted turns: look for smoke. > > Most likely just poor regulation... add some more load on the 6.3 and > see if it gets sensible. Phil A knows mains transformers and will > no-doubt be around to correct me if I am mistaken.I'll re-open the thing soon and post more data. The transformer itself is really small, maybe rated 15VA so the regulation and efficiency will be pretty terrible to start with. I think I was measuring 7.5 VAC out, with the load of a single tube, this seemed wrong, but I don't work with tubes. Will have to snip the leads off to really test further.
