Bad Omen?
in [Design]
|
Prev: DC motor opinion/question
Next: RPM Meter
From: Sergey Kubushyn on 29 Jul 2010 21:55 Joerg <invalid(a)invalid.invalid> wrote: > Sergey Kubushyn wrote: >> Joerg <invalid(a)invalid.invalid> wrote: >>> Sergey Kubushyn wrote: >>>> Joerg <invalid(a)invalid.invalid> wrote: >>>>> Sergey Kubushyn wrote: >>>>>> Joerg <invalid(a)invalid.invalid> wrote: >>>>>>> Sergey Kubushyn wrote: >>>>> [...] >>>>>>>> Just one example--I recently tried to buy several thousands of >>>>>>>> BC550/60C transistors. The funny thing was Avnet had BC560CTA @ $0.0163 >>>>>>>> each but no BC550C at all. I bought 2 ammopacks of 2,000 for $65 from them >>>>>>>> (that was all they had in stock.) On the other hand Arrow only had (and >>>>>>>> still have) BC550CTA at the same price but no BC560C at all. That was a >>>>>>>> couple of days ago. Now Avnet has 32K of BC550CTA in stock. If you were >>>>>>>> shopping at Avnet only a week ago you would've said that BC550C are >>>>>>>> unobtanium because they do not have them in stock while both findchips and >>>>>>>> octopart kept telling Arrow has plenty in stock. >>>>>>>> >>>>>>> Just what I said all along, should have gone to Digikey, they have >>>>>>> oodles of them: >>>>>>> >>>>>>> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=BC550CGOS-ND >>>>>> If you want to pay 3x the price, sure. And 7,055 pcs is not "oodles." And >>>>>> even those are just remnants, the other BC550Cxx are non-stocked. And this >>>>>> only one will also go non-stocked when they are bought. >>>>>> >>>>>> And they are exactly at the same point with BC560C. 4,000 left in stock at >>>>>> 2x price and a big fat warning they will go non-stocked once that inventory >>>>>> is sold. >>>>>> >>>>> Sergey, let's face it, nearly all thru-hole stuff is going to head for >>>>> lalaland. Ok, we were really early adopters over in Europe back then, >>>>> but since the start of my industrial career in 1986 I can't remember any >>>>> thru-hole board I have designed. And I've designed tons of boards. >>>>> >>>>> There will always be mfgs for thru-hole, just like Sovtek and Svetlana >>>>> do for tubes, but it's going to be boutique-ware. >>>> That is what I'm using them for. Not with tubes but for audio. >>>> >>>> The rumours about their death are grossly exagerrated. Fairchild makes those >>>> full steam and they are dirt cheap. Toshiba is back with their 2SK170 and >>>> 2SK369 parts that were discontinued long ago. And those parts are TO-92. >>>> BTW, Fairchild picked up a lot of Japanese transistors and now there is >>>> plenty of 2SA/SB/SC parts in their lineup. >>>> >>>> Definitely I could replace BC550/BC560 with SOT-23 BC850/BC860 but it >>>> doesn't make any sence because rest of the part is all big thruhole ones. >>>> Nobody makes SMD polystyrene capacitors, less for high-tolerance ones. There >>>> is no replacement for low-noise RN55/60 resistors (at least cheap one) for >>>> sub-millivolt audio circuits. I would love to make SMD version but there is >>>> no parts for that... >>>> >>> They won't go totally belly up by the only places I know that do >>> thru-hole mass production are all in China now. So some day you may have >>> to buy parts from Asia. >> >> Nah, I don't do mass-production of those. There is no _THAT_ many people who >> want to purchase a high-quality (not audiofool HiEnd one with inferior >> parameters but enormous price tag) phono corrector :) My program is a couple >> of thousands. And it is not just because of low demand but also because of >> component availability. I'm using Russian Military Surplus/Spare Parts >> Repository polystyrene capacitors, K71-1 with 0.5% tolerance and that is >> limited and finite supply. Once they gone they gone forever. >> >> That product is hand-assembled so I don't care who does mass production :) >> >>> If your needs are audio check out the BCX70k. Nice low 1/f corner. >> >> Thanks, but they are not any better than BC850/860. Roughly the same specs. >> >> BTW, I'd better go purchase a couple of reels of BC850C and BC860C while >> they are available (from Mouser :)) before they gone... >> >> It is not BJTs that are so rare, it is JFETs... I would've been extremely >> happy if 2SK369 existed in SOT-23... There is another problem though--I need >> matched pairs of those :( Not something that can be done with Pick-and-Place >> machine... >> >> There are Linear systems LSK389 but they are single source and not very >> reliable one... One should be out of his mind to design something with such >> a Maximese part... >> > > The only dual FETs I am aware of (I mean that are left) are RF > transistors. But it's MOSFETs. And even then you often down know how > they track because most are multi-chip, meaning just two devices in one > package, hoping that they come from the same area on the same wafer. > Even then tracking won't be good. There is LSK389 dual monolythic JFET from Linear Systems that is supposed to be a copy of Toshiba 2SK389 but they are not widely available. It is kinda boutique part. And they did not copy the 2SK389 p-channel twin, 2SJ109 :( So for the current production (since not so long ago) the only ones are single 2SK170/2SJ74 from Toshiba. They are TO-92 only... The better n-channel one, 2SK369 (it has twice the Yfs of 2SK170) unfortunately is not accompanied with a p-channel complement :( >> As for the capacitors, Panasonic makes SMD polyphenylensulfide (hope I >> spelled it right) ones that are supposedly on par with polypropylens but I >> didn't try them yet. And the tolerance issue remains--they are 5%... >> > > I've had that issue with 2x45 degree phase shifters in late 80s when > helping another team. Had told them not to use direct conversion but ... > > Anyhow, we paid through the nose for 0.5% film caps. For quality audio one should only use polystyrene or at least polypropylene capacitors so it is not just _film_ ones :) Russian surplus is not all that expensive but it is not easy to get and the supply is finite; they don't make them any more :( I'm paying something like $0.2-$0.35 when buying in bulk through my russian buddies close to those military warehouses. --- ****************************************************************** * KSI(a)home KOI8 Net < > The impossible we do immediately. * * Las Vegas NV, USA < > Miracles require 24-hour notice. * ******************************************************************
From: John Larkin on 29 Jul 2010 22:27 On Thu, 29 Jul 2010 23:45:42 GMT, Sergey Kubushyn <ksi(a)koi8.net> wrote: >Joerg <invalid(a)invalid.invalid> wrote: >> Sergey Kubushyn wrote: >>> Joerg <invalid(a)invalid.invalid> wrote: >>>> Sergey Kubushyn wrote: >> >> [...] >>>> >>>>> Just one example--I recently tried to buy several thousands of >>>>> BC550/60C transistors. The funny thing was Avnet had BC560CTA @ $0.0163 >>>>> each but no BC550C at all. I bought 2 ammopacks of 2,000 for $65 from them >>>>> (that was all they had in stock.) On the other hand Arrow only had (and >>>>> still have) BC550CTA at the same price but no BC560C at all. That was a >>>>> couple of days ago. Now Avnet has 32K of BC550CTA in stock. If you were >>>>> shopping at Avnet only a week ago you would've said that BC550C are >>>>> unobtanium because they do not have them in stock while both findchips and >>>>> octopart kept telling Arrow has plenty in stock. >>>>> >>>> Just what I said all along, should have gone to Digikey, they have >>>> oodles of them: >>>> >>>> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=BC550CGOS-ND >>> >>> If you want to pay 3x the price, sure. And 7,055 pcs is not "oodles." And >>> even those are just remnants, the other BC550Cxx are non-stocked. And this >>> only one will also go non-stocked when they are bought. >>> >>> And they are exactly at the same point with BC560C. 4,000 left in stock at >>> 2x price and a big fat warning they will go non-stocked once that inventory >>> is sold. >>> >> >> Sergey, let's face it, nearly all thru-hole stuff is going to head for >> lalaland. Ok, we were really early adopters over in Europe back then, >> but since the start of my industrial career in 1986 I can't remember any >> thru-hole board I have designed. And I've designed tons of boards. >> >> There will always be mfgs for thru-hole, just like Sovtek and Svetlana >> do for tubes, but it's going to be boutique-ware. > >That is what I'm using them for. Not with tubes but for audio. > >The rumours about their death are grossly exagerrated. Fairchild makes those >full steam and they are dirt cheap. Toshiba is back with their 2SK170 and >2SK369 parts that were discontinued long ago. And those parts are TO-92. >BTW, Fairchild picked up a lot of Japanese transistors and now there is >plenty of 2SA/SB/SC parts in their lineup. > >Definitely I could replace BC550/BC560 with SOT-23 BC850/BC860 but it >doesn't make any sence because rest of the part is all big thruhole ones. >Nobody makes SMD polystyrene capacitors, less for high-tolerance ones. There >is no replacement for low-noise RN55/60 resistors (at least cheap one) for >sub-millivolt audio circuits. I would love to make SMD version but there is >no parts for that... A thinfilm surface-mount resistor, Susumu or KOA maybe, should be indistinguishable from an RN55. Same Johnson noise, same (none!) shot noise. John
From: Sergey Kubushyn on 29 Jul 2010 23:34 John Larkin <jjlarkin(a)highnotlandthistechnologypart.com> wrote: > On Thu, 29 Jul 2010 23:45:42 GMT, Sergey Kubushyn <ksi(a)koi8.net> > wrote: > >>Joerg <invalid(a)invalid.invalid> wrote: >>> Sergey Kubushyn wrote: >>>> Joerg <invalid(a)invalid.invalid> wrote: >>>>> Sergey Kubushyn wrote: >>> >>> [...] >>>>> >>>>>> Just one example--I recently tried to buy several thousands of >>>>>> BC550/60C transistors. The funny thing was Avnet had BC560CTA @ $0.0163 >>>>>> each but no BC550C at all. I bought 2 ammopacks of 2,000 for $65 from them >>>>>> (that was all they had in stock.) On the other hand Arrow only had (and >>>>>> still have) BC550CTA at the same price but no BC560C at all. That was a >>>>>> couple of days ago. Now Avnet has 32K of BC550CTA in stock. If you were >>>>>> shopping at Avnet only a week ago you would've said that BC550C are >>>>>> unobtanium because they do not have them in stock while both findchips and >>>>>> octopart kept telling Arrow has plenty in stock. >>>>>> >>>>> Just what I said all along, should have gone to Digikey, they have >>>>> oodles of them: >>>>> >>>>> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=BC550CGOS-ND >>>> >>>> If you want to pay 3x the price, sure. And 7,055 pcs is not "oodles." And >>>> even those are just remnants, the other BC550Cxx are non-stocked. And this >>>> only one will also go non-stocked when they are bought. >>>> >>>> And they are exactly at the same point with BC560C. 4,000 left in stock at >>>> 2x price and a big fat warning they will go non-stocked once that inventory >>>> is sold. >>>> >>> >>> Sergey, let's face it, nearly all thru-hole stuff is going to head for >>> lalaland. Ok, we were really early adopters over in Europe back then, >>> but since the start of my industrial career in 1986 I can't remember any >>> thru-hole board I have designed. And I've designed tons of boards. >>> >>> There will always be mfgs for thru-hole, just like Sovtek and Svetlana >>> do for tubes, but it's going to be boutique-ware. >> >>That is what I'm using them for. Not with tubes but for audio. >> >>The rumours about their death are grossly exagerrated. Fairchild makes those >>full steam and they are dirt cheap. Toshiba is back with their 2SK170 and >>2SK369 parts that were discontinued long ago. And those parts are TO-92. >>BTW, Fairchild picked up a lot of Japanese transistors and now there is >>plenty of 2SA/SB/SC parts in their lineup. >> >>Definitely I could replace BC550/BC560 with SOT-23 BC850/BC860 but it >>doesn't make any sence because rest of the part is all big thruhole ones. >>Nobody makes SMD polystyrene capacitors, less for high-tolerance ones. There >>is no replacement for low-noise RN55/60 resistors (at least cheap one) for >>sub-millivolt audio circuits. I would love to make SMD version but there is >>no parts for that... > > A thinfilm surface-mount resistor, Susumu or KOA maybe, should be > indistinguishable from an RN55. Same Johnson noise, same (none!) shot > noise. Eh, this is not _THAT_ simple... If you look at CMF/RN datasheet, you'll notice that they explicitely tell about noise and voltage coefficient. I haven't seen any other resistor datasheet that had any mention to those two parameters. Ideal resistor is all Johnson noise. But there is no such thing as ideal resistor and all of them have additional noise, usually voltage dependent. Of all resistors CMF/RN are the only ones that have any mention of this. The other thing is voltage coefficient. Real resistor are not 100% linear and again CMF/RN is only one that explicitely provides this parameter. And finally, even though I'm not targeting audiofools, people get very suspicios seeing those tiny SMD resistors instead of gold standard RNs :) --- ****************************************************************** * KSI(a)home KOI8 Net < > The impossible we do immediately. * * Las Vegas NV, USA < > Miracles require 24-hour notice. * ******************************************************************
From: Sergey Kubushyn on 29 Jul 2010 23:46 Joerg <invalid(a)invalid.invalid> wrote: > Sergey Kubushyn wrote: >> Joerg <invalid(a)invalid.invalid> wrote: >>> Sergey Kubushyn wrote: >>>> Joerg <invalid(a)invalid.invalid> wrote: >>>>> Sergey Kubushyn wrote: >>>>>> Joerg <invalid(a)invalid.invalid> wrote: >>>>>>> Sergey Kubushyn wrote: >>>>>>>> krw(a)att.bizzzzzzzzzzzz <krw(a)att.bizzzzzzzzzzzz> wrote: >>>>>>>>> On Thu, 29 Jul 2010 01:10:20 GMT, Sergey Kubushyn <ksi(a)koi8.net> wrote: >>>>>>>>> >>>>>>>>>> Joerg <invalid(a)invalid.invalid> wrote: >>>>>>>>>>> Sergey Kubushyn wrote: >>>>>>>>>>>> Tim Williams <tmoranwms(a)charter.net> wrote: >>>>>>>>>>>>> "Martin Riddle" <martin_rid(a)verizon.net> wrote in message news:i2ntnv$o1h$1(a)news.eternal-september.org... >>>>>>>>>>>>>> Maybe they don't like paying 3x the price for those parts? >>>>>>>>>>>>> I don't know about that, I've shopped around and it's no worse than a factor of 2, with most of them being on par or better. >>>>>>>>>>>> As a matter of fact Mouser is not _THAT_ bad. It is almost on par with >>>>>>>>>>>> Arrow/Avnet/etc. Sometimes even cheaper. And in most cases their markup is >>>>>>>>>>>> less than 100%. >>>>>>>>>>>> >>>>>>>>>>>> That is another twin, DigiKey, that has everything marked up to the ears. I >>>>>>>>>>>> never understood why people do purchase anything from them... >>>>>>>>>>>> >>>>>>>>>>> Because they have the only search engine that works. >>>>>>>>>> Do they? >>>>>>>>> Yes. >>>>>>>> Have you ever tried findchips/octopart? >>>>>>>> >>>>>>> Have you tried the example I gave you this morning? >>>>>> So what? Findchips shows quite a bunch. >>>>> A mere fraction of what Digikey offers. >>>>> >>>>> >>>>>> ... And it is beyond my understanding >>>>>> why would one search for those... >>>>>> >>>>> Maybe because you don't design for mass production :-) >>>>> >>>>> I need to see the offerings of half a dozen mfgs right at my finger >>>>> tips. At Digikey I do, at Findchips I don't. >>>> Eh, if I need a million of 0.1uF ceramic capacitors I simply send an email >>>> to all my vendors and let them compete... >>>> >>> On my projects there usually isn't time for that. And this was just an >>> example. It's even worse for specialty stuff such as RF caps that are >>> high voltage. Without Digikey that would take forever. Like it did in >>> the early 90's. >>> >>> On my designs there are typically between 50 and several hundred >>> different discrete parts. >> >> I agree there are some reasons why people stay with them. They would've ran >> out of business if there were none :) >> >> But in my case there is nothing that would've justified paying a higher >> price for the same parts. I do even purchase from them on those rare >> occasions they have something in stock that nobody else does but that is >> extremely rare... >> > > I and my clients only purchase prototype quantities there. IME they are > mostly too expensive for larger production runs. On prototypes, however, > only time matters. Cost really doesn't. Yes, that's true. I also used to buy prototype parts from DigiKey. Then it shifted to DigiKey _and_ Mouser because the latter started having parts the former didn't have in stock or at all. Then it became Mouser and Digikey because Mouser almost always had most of the parts I needed and they were cheaper. Not a big deal for prototyping for mass production but quite significant for a business of one as I am. Now it is Arrow, Avnet, Quest, Mouser in that order, ocassionally Onlinecomponents, Allied, Newark, Future, America II, and extremely rarely DigiKey. I only buy from them if nobody else have something they have that is almost as rare as being striken by lightning four times in a row in one day... They used to have that database of the products they carry for OrCAD (I don't know if they still have something like this) but it was absolutely useless for me because I do not use OrCAD and even if I did it didn't have anything but their part no. and price -- no schematic symbols, no footprints, nothing. --- ****************************************************************** * KSI(a)home KOI8 Net < > The impossible we do immediately. * * Las Vegas NV, USA < > Miracles require 24-hour notice. * ******************************************************************
From: JW on 30 Jul 2010 06:30
On Thu, 29 Jul 2010 14:11:22 -0700 Joerg <invalid(a)invalid.invalid> wrote in Message id: <8be944Fih7U2(a)mid.individual.net>: >Spehro Pefhany wrote: [...] >> I like the hack that allows you to sort by price on Digikey (using >> Greasemonkey). Shame they don't incorporate it themselves. >> > >Hack? Where? Where? <pant ... pant> I believe he's referring to a Firefox add-on: https://addons.mozilla.org/en-US/firefox/addon/748/ |