Transistor equivalent to UK's BC183B?

The pages at DataSheetArchive.com suggest a BC239 or 2N5827 as being similar.

DigiKey's catalog lists some ON Semiconductor TO-92 parts such as the MPSA18 and BC546 and BC547 which may have sufficiently high minimum gain. For example the BC546 lists minimum 150, typical 300, and an fT similar to that of the BC183B. You might have to buy a few and hand-select one with high enough gain, or you might get lucky right out of the box. At under $2 for ten, you might as well stock up :-)

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Loads of them.

BC548B or C should be readily available.

Graham

Thanks, Actually right now I have 5 transistors laying around, maybe I could ask you if they will work, as I don't know much about them.

Two are marked C945 GR331

one is 1702L PH 8 d

one is 1502C PH 8 n

one is 1502C PH 8 7

Sorry if this is a mess, but thanks!! Chloe H.

Probably a 2SC945, an NPN high-frequency oscillator. Voltage rating seems high enough, fT seems plenty high. Gain might or might not be high enough... one manufacturer's data sheet says gain minimum 70, max

700, while the NEC data sheet says that their parts are graded into four different ranges (90-180, 135-270, 200-400, and 300-600).

It's probably worth a try.

With the leads pointed up and the flat side towards you, the leads will be base/collector/emitter in that order.

Those are probably some company's "house numbers" rather than a standard part number. You'd have to test 'em to figure out what they are and how they behave.

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GR = the green gain grouping. Which one was that ?

Graham

I suspect they're SMT devices. PH = Philips. Very small SMT parts almost never have the part number you'd expect. You need to know what it is to begin with to decode it from the data sheet.

Graham

The NEC data sheet lists them by letter-code - R, Q, P, and K, in the order I gave the gains. Micro Electronics seems to have used the same binning convention NEC did. Usha, in India, uses a slightly different binning convention (R 40-80, O 70-140, Y 120-240, G 200-400, L

350-700). I don't see notations on any of the data sheets which would indicate a color coding.

Using a transistor tester to figure out the hFE would probably be the quickest way to figure out if this one transistor might work in the metal detector circuit.

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It's the Japanese norm. Red Orange Yellow Green and Blue come to mind. If it's GR then it's fine.

Why not just buy a BC548B ( gain graded ) ? You can get those even in the USA !

Graham

The BC183 is a plain vanilla NPN silicon small-signal transistor (a bit out of date, although I think I have one), and the "B" gain group is the middle of the range gain (hFE 240-500 at 2mA Ic and Vce=5; typically

330). Not especially high voltage, not especially low noise. So quite a few transistors should fit in there. Unfortunately, unless you have the

-A, -B and -C (or -16, -25 and -40) gain range specification, which many Pro-Electron (BC... - most European small signal transistors) you may have to go through transistors like PN100 or 2N3569 with a gain tester, as others have suggested. The best idea is to hunt down something like the BC549B (see below).

For what it's worth, the background to that family of transistors goes something like this: the "BC" at the start identifies a silicon audio transistor (using the Pro-electron naming scheme, which I think is more helpful than JEDEC), and is reasonably easy to find explained on the internet, but there isn't exactly a formal system to the number part... what is NPN or PNP, for instance. But back around 1966 a family of TO-18 silicon transistors came out, BC107 to BC109, that not only became very popular, their number system became popular and so was copied by many other transistors, up to the present day. This is how it works: ..7 means high voltage, ..9 means high/gain and low noise, and ..8 means cheap - not especially great in any way. This was followed by BC177 to BC179 for PNP counterparts. Then BC147-9 and BC157-9 for "lockfit" plastic casing versions, and various other plastic case versions with the middle digit EVEN for NPN and ODD for PNP. A lot (but beware: not all) BC... transistors use the ..7/8/9 tradition, a common pinout that goes e-b-c (dating back to the AC126 and OC71), and odd/even middle digits indicating PNP/NPN... exceptions being ones like BC338, BC640, etc. Standardisation is a wonderful thing in the electronics industry; it is just a pity there are so many different standards to choose from!

An even more well-used tradition/standard is the gain group letters at the end: A for low gain, B for middle gain, and C for high gain. While the BC..7/8/9 family was becoming popular, Texas Instruments had Pro-Electron transistors BC182/3/4 (NPN) and BC212/3/4 (PNP) with high voltage/cheap/high gain signified by the last digit a bit like the 7/8/9 family. But they had letters like "L" at the end giving the pinout (e.g. b-c-e), not the gain. Quite a few US manufacturers (including Motorola) made transistors with Pro-Electron names, many making the BC182/3/4 series. It is interesting to see them swing, over time, to follow the -A/B/C suffix giving gain ranges (which is nice), while some European brands eventually moved away from that to use -25, -40 etc to show 250+ gain, 400+ gain, etc!

Back to the problem at hand: Many transistors popular in the US (e.g. the 2N4124, and 2N930 - is that still popular?) *may* have the appropriate gain, but they often lack the restricted gain range marking that ensures a particular transistor will have enough gain. You may have to try a few on an hFE tester to get one that is suitable. Or you could try something like a 2N5088 and know you have enough gain, but it has less current capability and base-emitter reverse voltage rating - which might not matter in your circuit, but I cannot be sure. Some of the good 2N.... equivalents, that are pretty likely to have a high enough minimum gain, are somewhat rare (e.g. TO18 can). There is, however, a really good answer...

The best idea, as Eeyore suggested, is to get one of those many transistors like BC547B, BC549B, etc that have the gain range specified; these are pretty common at mail-order parts suppliers like futurelec, jaycar and digikey, and pretty much the transistor-of-choice for general circuits from Australia to England so not likely to go obsolete any time soon. But not everyone stocks the restricted gain range versions, or specifies them in the catalogue (e.g. Jaycar simply says "BC549" but you are likely to get BC549B). Shop around for a supplier that advertises a BC549B or whatever - they are plentiful.

Other examples: BC109B, BC168B,BC169B,BC547B,BC548B,BC549B,BC546B, or BC550B. The -C gain group is even better. If you have to get a BC54- transistor without the gain group specified choose the BC..9 or BC550, since they pretty much always don't include much below a gain of 250.

Mark A

The e-b-c pinout ( or c-b-e ) is for compatability with TO-18 devices which the BC107/8/9 were.

Even today the BC547/8/9 are very popular modern equivalents together with the pnp BC557/8/9 complements.

Beware that the BC182/3/4 and BC212/3/4 had an 'L' variant e.g. BC183L with a b-c-e pinout like the popular JEDEC 2N3904.....family parts ( another series that refuses to lay down and die ! ).

Graham

Is "refuses to lay down and die" a derogatory term?

What do people keep in their junk box for misc transistors?

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Not at all.

Graham

BC549, BC556 and some of that family, plus 2N2222A, PN100/200, and MPF102 (used MPF102s for all sorts of things, for years, but starting to think I should use a different/cheaper JFET), plus whatever power transistors I have left over/pulled out (mostly plastic equivs of

2N3055/MJ2955 and various little fellas like MJE340 or BD639 that change all the time - no particular favourites for power transistors, just whatever will do).

I also have an assortment of static-sensitive devices like the 2N7000 and IRFP460 that aren't in my junk box, which I don't tend to use as much as I should, now I come to think about it... perhaps out of sight, out of mind.

I tend to use cheap quad opamps instead of transistors nowadays, even when a transistor would be fine. Although I've used microprocessors since 1978 I've managed to resist the temptation to use them all the time when a few transistors or opamps could do the job.

Mark A

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