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Voltage section[edit]

Currently says: The BC548 and BC549, and their PNP counterparts (BC558 and BC559) can be used in circuits where voltages reach no more than 30 Volts, limited mainly by their VCEO rating. The VCBO rating refers to the maximum voltage between collector and base with the emitter open-circuit (not typical operation),

This is wrong. Vcbo is the relevant voltage so long as you ensure the b-e junction doesn't get forward biased by stray currents leaking across the c-b junction. Nick Hill (talk) 13:07, 26 July 2015 (UTC)

It isn't that emphasizing Vceo is so much "wrong" as the cautious rating. Unless you know the external resistance in the base-emitter circuit is going to be low enough the safe way to go is to abide by the Vceo rating. There is a curve - although not always published for each transistor - relating the Vce breakdown rating as a function of the R between base and emitter... and the resistance needed to bring the Vcbr rating up to the Vcbo rating can be surprisingly low for small-signal transistors. Most amplifier circuits shun such low value resistors in the bias circuit because it cripples the current gain. There are other factors to complicate things, but the text in the article mentioned above (" mainly by their VCEO rating...") is gone now, and fair enough... such discussions complicate, and are not entirely relevant to, this particular article, but there should be something more on this question of which breakdown voltage to go by... perhaps more is needed in the Breakdown Voltage article?? It hardly says anything at the moment. Maitchy (talk) 02:34, 28 March 2017 (UTC)

Split off series sections[edit]

The series sections should really be separate articles, perhaps with this redirecting to the BC series article. (talk) 03:52, 27 March 2011 (UTC)

It's a reasonable direction to go in, but those two groups are too broad. OC71, OC81, OC91 and the OCP71 could well be covered by one article (probably just called OC71), but the OC28 is quite a different beast, even though germanium and a contemporary. Likewise BC is even broader - the BC107, BC108 & BC109 go together, but the BC548 et al. is a few decades later, with quite a bit changed in the intervening. There's scope for "series" articles, even bundling the complementary PNP & NPN together, but doing it just from the naming prefix is too wide. Andy Dingley (talk) 11:07, 27 March 2011 (UTC)
We have an article called Transistor and even an article called Bipolar junction transistor - is there any reason the history of development of these devices can't go into existing articles? At least, until the development and references get so big that it needs to stand on its own. --Wtshymanski (talk) 16:08, 27 March 2011 (UTC)
Transistor is much too general, BJT is also too general. These are two different classes of BJTs, silicon based and germanium based. The semiconductor industry revolves around the substrate... germanium, silicon, gallium arsenide, etc; these should all be separate articles since they have different characteristics. (talk) 05:48, 28 March 2011 (UTC)
BJT is about the theory, these are about the practical instances that became commercially significant.
2N2926 is another one that warrants mention, because of the practice in the mid-70s of selling them as colour-coded post-manufacture sorted examples according to their measured gain. Manufacturing of silicon transistors at that time had become cheap and reliable, but couldn't make parts to a consistent specification and so they needed to be sorted afterwards. Andy Dingley (talk) 10:20, 28 March 2011 (UTC)

Merge "BC548" specific material to 2N3904[edit]

A merge was suggested at the wikiproject, that BC548 be merged to 2N3904. This should obviously involve BC548 specific material. The series/family material would probably be better in a different article. (talk) 05:53, 28 March 2011 (UTC)

I'd want to check the specs carefully before deciding (although I suspect not). As "benchtop parts bin" transistors, these two are regularly swapped around (I'm in Europe. I've probably never used a 2N3904, but I bulk-buy BC548). However although they're substitutable for one another, they're not identical to one another (pinouts are, I think, different). Nor are their manufacturers commodity-manufacturing them to a common spec. For that reason they're not close enough to merge. Andy Dingley (talk) 10:25, 28 March 2011 (UTC)
You might want to check out what was done at 2N7000 then... (talk) 18:51, 28 March 2011 (UTC)
Is it the same device sold under both the JEDEC and Pro Electron numbers? Or is it just "close enough" for writers of TAB books? If it's got different pinout, ir surely can't be registered under both numbers. --Wtshymanski (talk) 19:36, 28 March 2011 (UTC)
Two different transistors, with power ratings where one is more than twice the other, are obviously not the same device. 8-( Andy Dingley (talk) 19:55, 28 March 2011 (UTC)
Oh cool. You can apparently get the JEDEC standard .PDFs for free on registering with their site ( which hasn't worked for me yet). Doesn't sound like a good candidate for a merge. --Wtshymanski (talk) 20:04, 28 March 2011 (UTC)

Hello everybody, I am the creator of this page originally and live in Australia. I created the page after reading the 2N2222 page. I have seen many North American Electronics publications (such as the ARRL Handbook) and the constant references to 2N2222s and 2N2907s etc. These JEDEC devices give a typically North American view, but this is not the only view that there is! In other Geographical Realms, other similar devices are more commonly available and used. I agree with Andy Dingely, whom is probably in the U.K. that the BC family of devices deserve a page of their own, distinct from the North American pages featuring JEDEC devices. I propose yet another page....has anyone ever pulled apart a piece of Asian Consumer Electronics and found dozens of 2SC1815s, well these are yet another manifestation of the BC548 and 2N3904. I have been to Viet Nam and there, in the Yersin electronics market in Ho Chi Minh City, (Sai Gon), there were no BC548s or 2N3904s to be seen or even known about, but 2SC1815s and their compliment, the 2SA1015, and be bought in bags of hundreds at a very cheap price and can be substituted for the other realm devces in most applications by simply "dogging the legs about" because the collector lead is in the middle. So this page serves to introduce those new to electronics, and dare I say, some too poor to purchase devices new and must resort to wrecking them out of discarded gear, a hand into electronics by realizing that the 2SC1815 they scavanged from an old Getto blaster on a rubbish heap is actually nearly the same as that 2N3904 in the window of the local electronics dealer.

I hope to also use this page, and others like it, to share my considerable knowledge as an electronics technician for thirty years with a hopefully curious enough up and coming generation, because i won't be much good to anyone once I go up the Crematorium Chimney.

Globe Collector (talk) 11:27, 16 April 2011 (UTC)

I have compared data sheets for both BC54x and 2N3904. They appear to be quite different devices. BC54x would apparently be a superior replacement for the 2N3904 where gain linearity will improve circuit performance. Obviously, BC548 would not substitute a 2N3904 if the circuit needs to switch more than 30v. The article defines parameters (incidentally, erroneously) when the parameters are equally valid over thousands of different component part numbers. The article appears to be a verbose version of what can tersely be included in a table of common BJTs along with their key parameters and notes.I recommend deleting all pages such as 2N3904 2N2222 BC108 family then link them all to one page containing a table.

So they're different devices, but you advocate merging anyway?
These are never going to be long articles. Nor do they replace other broader articles on bipolar transistors or even a new article (mostly based on a comparison table) for small signal transistors. We can have both, we're just not limited by page count. But I see no reason given here why merging and deleting the article under this title would be an improvement. Andy Dingley (talk) 17:02, 26 July 2015 (UTC)

If we wanted to have information on 15 products, differing in only details, would it be better to have 15 pages, with most of the information duplicated across all those pages with edits here and edits there, some being good, others introducing errors, or would it be better to summarise what the devices do in general, describe the salient parameters, then list the devices showing the salient parameters?

I propose a table along the lines of this. This way, a hobbyist can make their own mind up about the cross compatibility, and all the information is easily accessible. Article should show a diagram of a TO18, a TO92 with pin numbering and explain Ic Vcb Vce Hfe Ft .

I don't expect there to be 15 articles, more like four or five and that's reasonable. One per family, not per part. BC107 / BC108 / BC109 would certainly be in one article. So should complementary PNP/NPN pairs. The BC548 can merge similarly with its family. We might even merge the two of them, as their history does overlap. Merging in the 2N2222 and the 2N3904 families? Only if it's sourceable that there's similar overlap. Andy Dingley (talk) 18:42, 26 July 2015 (UTC)

I suppose we need to approach this from the perspective of what would someone visiting a page or array of pages, most useful. If it is about the history of the companies involved, then we would start with the company, the designers, the processes then the parts themselves.

If we are talking about Transistors from a functional and usefulness perspective, we would generalise in an order similar to most catalogues: 1) It's a transistor 2) it's bipolar 3) Silicon 4) Small signal Ptot <=1W 5) Part numbers, salient parameters and what they would be most useful for.

Couldn't all relevant information about small signal silicon bipolar transistors live on one page, and wouldn't this make sense? Indeed, if the information isn't extremely detailed, see how it grows, have a page on silicon bipolar transistors with sections going into details of examples of small, medium and high power. A table for each category with perhaps 20-30 examples would be a great cross reference and information resource. It doesn't seem to make sense to spread it over a large number of pages as the same information will tend to be repeated time and again. Nick Hill (talk) 19:01, 26 July 2015 (UTC)

That's an argument in favour of creating an article on (list of)? small signal silicon bipolar transistors. Great article, go for it.
We're not constrained to avoid overlaps though, we can keep both. So no argument in favour of creating the broad list is a strong argument to delete the narrow articles.
Some of these families are sufficiently significant that they do warrant individual articles and textbook WP:Notability is easily met by almost all of them. There are a few that are less clear, mostly those important in the early years and now obsolete. Does the BC107 belong in a current list? I think (opinion, not sourced) that those belong in a section of the BC548 article as important ancestors, but don't have much relevance for ongoing use. Worth adding to the list for comparison though. The 2N2926 is another one: important historically and for its widespread use of post-manufacture hfe coding with coloured dots, but no one has specified one for new use in years. That should be in the list, but probably not with an article. Andy Dingley (talk) 22:09, 26 July 2015 (UTC)

Table of common small signal transistors[edit]

Typical values. Refer to specific manufacturer's data sheets. Case numbering looking from below. TO18 pin 1 next to tab, counting clockwise. TO92 flat facing up, 1 to the left.

Type Ic (ma) Vcb Vce Hfe Ft Ptot (Mw) Pin Layout
1 2 3
Case Notes
BC546 NPN 100 80 65 100-800 300 500 C B E TO92 Linear gain [1]
BC556 PNP 100 80 65 100-800 150 500 C B E TO92 Linear gain [2]
BC107 NPN 100 50 45 100-800 150 600 E B C TO18 Replaced with BC547 [3]
BC547 NPN 100 50 45 100-800 300 500 C B E TO92 Linear gain [1]
BC557 PNP 100 50 45 100-800 150 500 C B E TO92 Linear gain [2]
BC108 NPN 100 30 25 100-800 150 600 E B C TO18 Replaced with BC548 [3]
BC548 NPN 100 30 30 100-800 300 500 C B E TO92 Linear gain, Low noise [1]
BC558 PNP 100 30 30 100-800 150 500 C B E TO92 Linear gain, Low noise [2]
BC109 NPN 100 30 25 100-800 150 600 E B C TO18 Lower noise version of BC108
Replaced with BC549 [3]
BC549 NPN 100 30 30 100-800 300 500 C B E TO92 Linear gain, Low noise [1]
BC559 PNP 100 30 30 100-800 150 500 C B E TO92 Linear gain, Low noise [2]
BC550 NPN 100 50 45 100-800 300 500 C B E TO92 Linear gain, Low noise [1]
BC560 PNP 100 50 45 100-800 150 500 C B E TO92 Linear gain, Low noise [2]
2N3904 NPN 200 60 40 30-300 270 625 E B C TO92 Non-linear gain [4]
2N3906 PNP 200 60 40 30-300 250 625 E B C TO92 Non-linear gain [5]
NPN 600 75 40 35-300 250 500 E B C
Non-linear gain [6]

Nick Hill (talk) 19:47, 26 July 2015 (UTC)


Why do Pro Electron devices come in JEDEC packages? Surely they would at least have come up with their own metric packages. --Wtshymanski (talk) 03:27, 4 April 2011 (UTC)

What time period are you talking about? There's a lot more use of common package formats today than there was in the '70s. As JEDEC packages are workable, the obvious encouragement is to use them for nearly everything and only use a non-"mainstream"(sic) package if there's a real need to, leaving the metal TO18 cans to those devices that really need them. The increased shift from hand-assembly to pick-and-place is also going to favour standard packages and in-line leads, rather than triangular pin spacings (easier to hand place, but harder to machine place). There's also the cost aspect, as plastic packs are cheaper than cans.
For this particular transistor, there's a widespread view (dating back to the '80s) that it's just the old favourite BC107 (metal TO18 can) in a TO92 plastic package with flat leads. I don't know how true this ever was "under the hood", but it was a widely held pragmatic viewpoint that built an awful lot of circuits. Andy Dingley (talk) 09:04, 4 April 2011 (UTC)
The 0.1 inch pitch of some circuit boards, and probably what automatic assembly equipment was designed to, would have affected the choice of package dimensions for quite a while. I'm not sure why the Mullard/Philips lockfit transistors stuck to the same 0.1" pitch... the timing of Englands switch to metric may or may not have been a factor there. Maitchy (talk) 04:56, 17 March 2014 (UTC)
Independent of time period; surely the European manufacturers couldn't bear to adopt American standards? The Chinese, of course, will build anything you like to any price point you like. And the above discussion (with citations) would be interesting in an article about Transistor packages which could merge in the rat-bag listing of random TOXXX articles we have now. Organizations such as National Semiconductor regularly put in the process and die used to make various transistors, this nformation can't be too super secret if National is disclosing it. There's got to be something written about this that's more authoritative than "Build this code practice oscillator in only 13 separate articles" that the hobby magazines print. --Wtshymanski (talk) 13:35, 4 April 2011 (UTC)
The English valve (tube) socket standards were sometimes a case of "copy what the USA does as fast as possible", sometimes they resolutely stuck to their old standard, and sometimes made a bit of a change to make it darned difficult to substitute a different device for their own odd standard (e.g. an octal socket which almost-but-not-exactly International Octal holes). Maybe some of that continued into the semiconductor era? For example, Philips/Mullard sold 2N3055's and other popular RCA types soon after they came out in America, plus they made their own "BDY20" which I still don't know how it differs from a 2N3055. On the other hand, it took a long time for US manufacturers to take on board European device types (but when they did, they did it very well), so decades of (say) US ARRL books never mention European transistors while electronics magazines in Australia, England, Continental Europe, etc have had a reasonable percentage of 2N... types since the 1960's. Maitchy (talk) 04:56, 17 March 2014 (UTC)


This part number is not notable and is not a suitable topic for an encyclopedia article. Even history books about the semiconductor business don't spend any time on individual part numbers, because they aren't important to understanding semiconductors and thier roles. --Wtshymanski (talk) 13:38, 5 April 2011 (UTC)

Haven't you just finished an AfD on this? What's the point of opening the discussion again? SpinningSpark 21:30, 5 April 2011 (UTC)
Someone keeps pulling the notability tag off the article. I think the concern should be recorded, so the talk page looks like a place to note that this part number is not notable. --Wtshymanski (talk) 17:46, 6 April 2011 (UTC)
The thing is that some individual type numbers (for transistors, ICs, pentodes, etc) are so well known amongst the electronics fraternity that knowledge of them is kind of taken for granted by some people and any reader of a huge number of electronics hobby magazines is going to want to know about them - not just look up the specs, but will need to understand something more than that. One example is the 555 timer; I'd say there are lots of others - for example if somebody sees a 7474 specified it is pretty much taken for granted that a knowledgeable person should immediately say to themselves "Ah! that is obviously an TTL J-K Flip Flop... I might be able to use a 74HC74 in its place", or failing that they might at least recognise "74.." probably is shorthand for "SN74.." then "But the original 74.. series is old and power-hungry, but there's a whole lot of 74xyz... types with the same pinouts to consider". So all of this goes beyond the simple historical development type of approach. It needs an encyclopedic entry that explains what its all about, for average readers who stumble across some of these famous devices. And I'd say the same sort of comments can be said about BC108 transistors and their relationship to BC548s (in fact: BC546 to BC550)... many, many electronics people in England, Australia, etc will know a lot about them, probably consider them "jelly beans" (do people still use this term for cheap all-kinda-similar devices used where super quality doesn't matter?), but their famousness depends on where in the world you are. There are (2S)A.... types absolutely famous in Asia, as another example. It would be terrible if Wiki articles got shot down because of USA-centric ideas of what is noteable. Maitchy (talk) 09:58, 15 February 2015 (UTC)
That's not the problem. The problem is WP:NOTABLE - individual spare parts aren't notable. --Wtshymanski (talk) 19:13, 16 February 2015 (UTC)
The BCxx7/8/9 family is very notable (for reasons I mentioned below - the magnitude of its prominence in Europe/Australasia plus the simple need many readers will have in knowing something about it) plus, I should add: it is notable because of its position in the history of the semiconductor industry. I have just finished reading some histories of early transistors from the point-contact days on to the 1960s and beyond... there are devices like the OC50, 2N34, 2N280, OC10, and OC71 that keep being mentioned in each article, and if they go far enough, the BC108 family. I totally agree it is not appropriate to have every silly little device like a 2SA123 or NKT456 mentioned but the BC548 family is notable and deserves inclusion more than some others that have articles here. Maitchy (talk) 02:57, 28 March 2017 (UTC)

Historical Significance of BCxx7/8/9 Series[edit]

The BC548, and the family it belongs to, are VERY notable in Europe and places like Australia/New Zealand, but some of the comments on this page are understandable given the way that some types were famous in half of the world but hardly known in the other half. There are many references that could (and should) be brought in to show the significance of the family that can be described by the neat table:

Case Polarity 80Vcbo 50Vcbo 30Vcbo Low-Noise 30V Low-Noise 50V
TO-18 NPN BC107 BC108 BC109
PNP BC177 BC178 BC179
Lockfit NPN BC147 BC148 BC149
PNP BC157 BC158 BC159
NPN BC167 BC168 BC169
PNP BC257 BC258 BC259
(c-b-e) 350mW
NPN BC237 BC238 BC239
PNP BC307 BC308 BC309
NPN BC317 BC318 BC319
PNP BC320 BC321 BC322
(c-b-e) 625mW
NPN BC546 BC547 BC548 BC549 BC550
PNP BC556 BC557 BC558 BC559 BC560
SMD NPN BC846 BC847 BC848 BC849 BC850
PNP BC856 BC857 BC858 BC859 BC860

(see also: [1] for a neat summary of some of the family).

One typical reference is: [2], another is a news item in Practical Wireless (I think it was) when the grandparents of the family were introduced around 1966 (I don't have that reference to hand, but could find it). The fact is that the BC107/8/9 family became the most common types to be specified in magazine articles and so on for many years after the days of the OC71 and before the plastic versions BC547/8/9 took over. The Australian Philips "MiniWatt" article I just mentioned begins with a statement saying how important the BC107/8/9 transistors were.

Where the criticisms on this page have something worth noting is that there is a lack of encyclopedic information, and this could and should be expanded. The article should show:

  • how to understand the pattern in the naming scheme (BC10x = TO18-cased NPN, BC17x = TO18 PNP; BC14x = lock-fit NPN, BC15x = lock-fit PNP; BC54x = TO92ebc NPN; BC55x = TO92ebc PNP, and probably BC8xx SMD versions), and the meaning of final the 7/8/9 (etc) and optional A/B/C.
  • the historical progression from TO-18 to lockfit then TO92 them surface-mount
  • The part Philips/Mullard had to play in this history
  • some indications of how popular these were in some parts of the world (and maybe links to the alternative types popular at the same time in the USA and Japan?)
  • the common features, such as 0.1A continuous collector current rating, roughly 300mW power free-air dissipation (and how it varies with package type), fT, and how these features mark it is a "general purpose" silicon transistor for many audio and low-MHz RF applications.
  • possibly needed is a link here to an article listing (what some people call) "jellybean" transistors like the BC548 - the very common general-purpose types which have many, many substitutes... often I see people posting questions on one Internet forum or another "what is a good replacement for (some really common type)?" which a google search should point people to an article saying "you can replace any of these cheap transistors with any other in the same family with higher ratings (e.g. BC548 can be replaced by a BC547 or BC546) or better noise specification (with a BC549) or in a different package with the same/better ratings if the different pinout and power dissipation is checked). It needs to be said somewhere that if anybody specifies a BC548 or BC108 etc for a circuit they are saying many parameters aren't too important and so (with a few caveats) just about any transistor of the correct polarity can be used in its place.
  • possibly mention Process Numbers (e.g. Motorola uses Process 10 for many of the NPN members of this family)
  • other European BCxx7/8/9 series (such as BC167/8/9) that match the pattern plus some of the notable BCxx7/8 types that should not be confused with this series (e.g. the popular BC327/8 isn't really related, is it?)

I certainly think the BC548-family article is needed, and trying to cover this only in something spanning all BCxxx types would be a mistake - it is too notable a group of transistors. Maitchy (talk) 00:17, 17 March 2014 (UTC)


Most of this article isn't about its putative subject. Aside from the parts list data sheet numbers, we still haven't been told anything about *this* transistor type. What company first registered it, and when? Is it still made? Are as many being made now as in, oh, say, 1978? Do we know anything notable about this transistor at all? --Wtshymanski (talk) 18:48, 17 April 2011 (UTC)


What is the purpose of this page? So far I see

  • data sheet info, widely available
  • discussions of numbering/naming schemes, which I dont see being specific to any one transistor type
  • mention that its popular, as are many trs
  • discussion of some nonstandard diode naming (DUN)

If people want datasheet type content, there's a vast amount of it available, and someone could write thousands of new pages. (talk) 14:48, 24 July 2011 (UTC)

Yeah, see above ( and this spring's rather bitter AfD nomination discussions, the very model of the collegial process that the Wikipedia is so justly famous for). You're welcome to put your hand into the wood chipper if you like, but I'm still waiting for the scars to heal. Every single part number of anything ever made is a notable topic for the encyclopedia, you see; the fanboys will mass in hordes if this article is nominated for merging or deletion again. --Wtshymanski (talk) 15:56, 24 July 2011 (UTC)
Yes, I agree with your sentiments entirely Wtshymanski. Do you want to see my scars? -- Alan Liefting (talk) - 20:20, 24 July 2011 (UTC)
I've just noticed we've carefully linked to the articles for volt, watt and amp but we dno't explain what a Vcbo or a Vceo is. Nor do we give a fig about explaining what an Ft is nor what you should do if one comes at you in a dark alley. Too bad the editors exhausted themselves in the AfD and now have no energy to work on making this an article instead of a random essay. --Wtshymanski (talk) 14:49, 27 February 2012 (UTC)
Maybe the editors are just pissed off at your continual sniping. I know one who certainly is. Andy Dingley (talk) 16:18, 27 February 2012 (UTC)
"The BC548 was first made by we don't know who, and we don't know when. We have no idea if they are still made, nor how many were made in a typical year. Wikipedia can't tell you how this transistor compares with other similar devices because we don't know. We don't even know what they were used for, or why they were invented in the first place. We can't tell you what a Vcbo or a Ft is. If you want to find out about this device, Google for it. " --Wtshymanski (talk) 22:43, 27 February 2012 (UTC)
WP:SOFIXIT and stop whining. Andy Dingley (talk) 22:46, 27 February 2012 (UTC)
Wikipedia CAN tell you that Ft is the abbreviation for the Hungarian forint, that Vcbo is a Salt Lake City architectural firm, that Ic stands for Interstitial Cystitis, but Wikipedia can't tell you anything about Ptotal (though it thinks you may have meant "total"). Wikipedia isn't even as good as a real parts catalog, which would *define* all the gobbletygook on page iii of the parts substitution guide which you should have consulted instead of an encyclopedia. I tried to fix this but the obvious solution got shot down.--Wtshymanski (talk) 22:50, 27 February 2012 (UTC)
I found a good treatment of transistor data on the Dutch wikipedia: [3]; my view is that the transistors that get an article dedicated to them should be very few, and selected because they are very significant, but there are families of devices (the best example being the BCxx7/8/9 family here) that are interesting for more than just an opportunity to quote some specifications off a datasheet. The 2N3055 is one that is interesting in its own right - it had an interesting development, has lasted many decades, and was a milestone in the history of electronics (as was the NE555 timer and the 741 opamp) whether we still use them or not... one of the key questions is whether it helps a reasonable number of readers to be able to see what somebody might mean when they write something that assumes everyone knows what a 741 or BC108 or 555 or 2N2222 is. Maitchy (talk) 04:56, 17 March 2014 (UTC)
I have added some links and explanations for Vcbo/Vceo breakdown terminology. Hope that helps. Maitchy (talk) 04:56, 17 March 2014 (UTC)
I notice much (most?) of the content of this article isn't about the BC548 at all. Articles are about their subjects. --Wtshymanski (talk) 00:02, 1 January 2015 (UTC)
I see your point about much of the article talking about the family of devices than contains the BC548; I will try to adjust that. But remember that the naming convention gives us "BC548A" and "BC548B" etc (as obviously relevant for this article on the BC548, but the higher-voltage and lower noise versions of the BC548 have their last digit changed (e.g. BC547 or BC549) yet they are still very much related... so is it better to have an article called something like BC54x and have BC548 (etc) redirect there? I personally don't think "BC54x" is a good article name because it doesn't actually exist as a device, but compare the situation with something like the 6L6 article where variants are mentioned - and I think everybody finds that totally fine. I t is a question of finding a reasonable balance. Maitchy (talk) 05:05, 7 April 2015 (UTC)
Leave the name at BC548, until such time as someone has a visionary idea for a better one.
Transistor families BTW are drawn at several levels:
  • Collector current limits. This is not part of the same family. A larger die is needed, the finished parts may sell for a higher price, they're considered to define separate component families.
  • PNP / NPN complementary pairs. Obviously these are useful to the users of the devices, so it's an obvious thing to try and manufacture. Even though, especially in the early days of LEDs, it turns out that complementary doped semiconductors just don't want to play ball or to behave as epitaxially interchangeable partners. Even though these may be substantially different designs, tailored to make the electrical behaviours match, they're placed in the same family for marketing reasons.
  • Encapsulation. Metal or resin, with appropriate temperature ratings and maybe a different collector current derating as a result. (NB - that's not the same thing as collector current noted above.) Usually, but not always, the same family. Sometimes it also involves differences like production in cleaner clean rooms, or on sites that are more trusted to make reliable parts - especially for long-term space-rated hardware.
  • Voltage rating. This is usually a matter of layer thicknesses and breakdowns. The same design is used, but process times are changed. It's a decision made after design and before manufacture, so they're considered as part of the same family, but a different part number, usually sequential.
  • Gain. This is (and mostly 'was', back when production to consistent gains was hard) a matter of grading after production. The part number is a suffix, or even a coloured paint spot. Certainly within the same family as they aren't even identified as to grade until after manufacture. Some parts, like the CK722, used sequential numbers for this grading.
Why has epitaxy been removed from this article? It's pretty crucial. Andy Dingley (talk) 08:57, 7 April 2015 (UTC)

A few edits[edit]

I came to this article because I am doing up a circuit that uses the BC548, and it isn't as common in North America as it is in Europe and the UK. So I thought: I'll read up!

The article, before I went to work on it with a few dozen or more edits, was tagged as Refimprove and "incomprehensible", or "too technical". I have to agree. It was a fairly large assortment of very technical info. I made quite a large number of edits based on the following:

  • Wikipedia is an encyclopedia for a general readership, not a place to lay out technical info that is better held in the actual datasheet. Think about it: the ultimate arbiter for the HfE of a transistor is the manufacturer, not Wikipedia. If you are going into production you will look to the datasheet for the VCE breakdown voltage, not Wikipedia.
  • Following from the above, readability is key, and I made many edits to try and improve this.
  • I removed some factualy incorrect info. For example, it is produced by ON Semi and Fairchild, so it is available through their distributors globally. I had zero trouble buying a couple the other day in North America. Digikey, Mouser, Farnel, etc all distribute it, so it can be gotten anywhere that there is mail or courrier service. Also, it appears to be only produced by Fairchild and ON Semi these days.
  • I added four or five references and cleaned up some others. The article was chockablock with well-meaning but largely unreferenced statements.

In any case, I think it now reads well. It brings out the main points:

  • it's a common transistor that is
  • widely known in the electronics field, and
  • it has the following basic characteristics.

For more info, see datasheet!HappyValleyEditor (talk) 02:36, 8 March 2016 (UTC)