Rebranded transistors?
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From: Jan Panteltje on 18 Feb 2010 09:52 I ordered some BC557 from Conrad.nl. Normally you can hardly red what is written on a transistor, but in this case the label is silver painted masked, and does not say 'BC557', but 'B557C': ftp://panteltje.com/pub/strange_transistors/BC557_rebranded_img_1806.jpg Also it looks like the top has been grinded so as to remove any original marking. I scraped of some of the silver painted text, but I could find nothing under it. On one of these I thought I could make out the number '2' on the top, but then there are people whio see the strangest things in random patterns, so I am not sure: ftp://panteltje.com/pub/strange_transistors/BC557_top_img_1808.jpg Any body has any idea what the difference is between a BC557 and a C557B? Or is it a BC557B? Or just any thing painted with the required number? Other transistors (BC547) look totally normal from Conrad. I got a bit supicious when one of these did not work as expected, measured the beta, about 330 at low currents, but seems to drop to much lower at 100 mA.
From: John Larkin on 18 Feb 2010 10:30 On Thu, 18 Feb 2010 14:52:25 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >I ordered some BC557 from Conrad.nl. >Normally you can hardly red what is written on a transistor, >but in this case the label is silver painted masked, >and does not say 'BC557', but 'B557C': > ftp://panteltje.com/pub/strange_transistors/BC557_rebranded_img_1806.jpg > >Also it looks like the top has been grinded so as to remove any original marking. >I scraped of some of the silver painted text, but I could find nothing under it. >On one of these I thought I could make out the number '2' on the top, >but then there are people whio see the strangest things in random patterns, >so I am not sure: > ftp://panteltje.com/pub/strange_transistors/BC557_top_img_1808.jpg > >Any body has any idea what the difference is between a BC557 and a C557B? >Or is it a BC557B? >Or just any thing painted with the required number? > >Other transistors (BC547) look totally normal from Conrad. >I got a bit supicious when one of these did not work as expected, >measured the beta, about 330 at low currents, but seems to drop to much lower at 100 mA. http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=222900688 John
From: pimpom on 18 Feb 2010 10:46 Jan Panteltje wrote: > I ordered some BC557 from Conrad.nl. > Normally you can hardly red what is written on a transistor, > but in this case the label is silver painted masked, > and does not say 'BC557', but 'B557C': > ftp://panteltje.com/pub/strange_transistors/BC557_rebranded_img_1806.jpg > > Also it looks like the top has been grinded so as to remove any > original marking. > I scraped of some of the silver painted text, but I could find > nothing under it. > On one of these I thought I could make out the number '2' on > the top, > but then there are people whio see the strangest things in > random > patterns, > so I am not sure: > ftp://panteltje.com/pub/strange_transistors/BC557_top_img_1808.jpg > > Any body has any idea what the difference is between a BC557 > and a > C557B? > Or is it a BC557B? > Or just any thing painted with the required number? > I've occasionally had batches of BC547s and BC557s marked just as in the first picture, printed on the silvered front face of a TO92 case with the leading 'B' omitted. I didn't measure the beta carefully but never encountered any unexpected results on using them. As for the missing B, I assumed that some manufacturers were following the Japanese practice of omitting the leading '2S' from their type numbers, presumably to enable using reasonably large characters on a limited surface area. I remember saying to a friend when I first came across such markings on European type transistors, "Oh oh, this could lead to some confusion. There may be times when we can't be sure if it's BCxxx or 2SCxxx." > Other transistors (BC547) look totally normal from Conrad. > I got a bit supicious when one of these did not work as > expected, > measured the beta, about 330 at low currents, but seems to drop > to > much lower at 100 mA. The beta vs. Ic curve on Philips' datasheet for a typical BC557B gives beta of ~320 at 1mA and ~170 at 100mA. I don't find this surprising as 100mA _is_ the maximum continuous Ic rating, and it's quite normal for Si transistors to show considerable drops in beta as we approach max Ic.
From: Jan Panteltje on 18 Feb 2010 10:59 On a sunny day (Thu, 18 Feb 2010 21:16:06 +0530) it happened "pimpom" <pimpom(a)invalid.invalid> wrote in <hljnc5$5pm$1(a)news.albasani.net>: >Jan Panteltje wrote: >> I ordered some BC557 from Conrad.nl. >> Normally you can hardly red what is written on a transistor, >> but in this case the label is silver painted masked, >> and does not say 'BC557', but 'B557C': >> ftp://panteltje.com/pub/strange_transistors/BC557_rebranded_img_1806.jpg >> >> Also it looks like the top has been grinded so as to remove any >> original marking. >> I scraped of some of the silver painted text, but I could find >> nothing under it. >> On one of these I thought I could make out the number '2' on >> the top, >> but then there are people whio see the strangest things in >> random >> patterns, >> so I am not sure: >> ftp://panteltje.com/pub/strange_transistors/BC557_top_img_1808.jpg >> >> Any body has any idea what the difference is between a BC557 >> and a >> C557B? >> Or is it a BC557B? >> Or just any thing painted with the required number? >> > >I've occasionally had batches of BC547s and BC557s marked just as >in the first picture, printed on the silvered front face of a >TO92 case with the leading 'B' omitted. I didn't measure the beta >carefully but never encountered any unexpected results on using >them. As for the missing B, I assumed that some manufacturers >were following the Japanese practice of omitting the leading '2S' >from their type numbers, presumably to enable using reasonably >large characters on a limited surface area. OK, but then why grind of the top? >I remember saying to a friend when I first came across such >markings on European type transistors, "Oh oh, this could lead to >some confusion. There may be times when we can't be sure if it's >BCxxx or 2SCxxx." Yes, numbers should be the way they are. > >> Other transistors (BC547) look totally normal from Conrad. >> I got a bit supicious when one of these did not work as >> expected, >> measured the beta, about 330 at low currents, but seems to drop >> to >> much lower at 100 mA. > >The beta vs. Ic curve on Philips' datasheet for a typical BC557B >gives beta of ~320 at 1mA and ~170 at 100mA. I don't find this >surprising as 100mA _is_ the maximum continuous Ic rating, and >it's quite normal for Si transistors to show considerable drops >in beta as we approach max Ic. Maybe these are genuine, but I would prefer a label like 'Philips' or 'Motorola' or whatever. Why hide the manufacturer? Or does 'W' stand for some company? Maybe someone in China is just spray-painting a lot of universal PNPs :-) And you also had some of those :-)
From: Jan Panteltje on 18 Feb 2010 11:00
On a sunny day (Thu, 18 Feb 2010 07:30:10 -0800) it happened John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in <47nqn5tj28k8tpqgb3nre51jkpjo9fu3c8(a)4ax.com>: >On Thu, 18 Feb 2010 14:52:25 GMT, Jan Panteltje ><pNaonStpealmtje(a)yahoo.com> wrote: > >>I ordered some BC557 from Conrad.nl. >>Normally you can hardly red what is written on a transistor, >>but in this case the label is silver painted masked, >>and does not say 'BC557', but 'B557C': >> ftp://panteltje.com/pub/strange_transistors/BC557_rebranded_img_1806.jpg >> >>Also it looks like the top has been grinded so as to remove any original marking. >>I scraped of some of the silver painted text, but I could find nothing under it. >>On one of these I thought I could make out the number '2' on the top, >>but then there are people whio see the strangest things in random patterns, >>so I am not sure: >> ftp://panteltje.com/pub/strange_transistors/BC557_top_img_1808.jpg >> >>Any body has any idea what the difference is between a BC557 and a C557B? >>Or is it a BC557B? >>Or just any thing painted with the required number? >> >>Other transistors (BC547) look totally normal from Conrad. >>I got a bit supicious when one of these did not work as expected, >>measured the beta, about 330 at low currents, but seems to drop to much lower at 100 mA. > >http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=222900688 > >John Thank you John, that article sure makes one wonder. |