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Jellybean hobbyist general purpose transistors..

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David Hess:

--- Quote from: Vtile on October 19, 2017, 02:18:37 pm ---It would be interesting to know if the garden variety actually do have different internals between models or are they actually just from one outcome from a machine and then sorted to meet different key specifications of garden variety part numbers. I wouldn't be too surprised (without having even general knowledge of semiconductor production) if this would be the case looking at how close the specks are in many parts.
--- End quote ---

It is common for one design to result in multiple part numbers and it happens with some ICs as well.  Bipolar transistors are often graded for Vce and of course hfe to be divided into different part numbers.  Some power MOSFETs are graded for Vds like Vce in bipolars.  Besides things like offset voltage, bias current, and offset voltage drift, many old bipolar operational amplifiers were also graded into 28, 36 and 44 volt versions.

And as mentioned earlier, some part numbers like the 2N3055 become a dumping ground for other parts which did not meet their intended specifications.

T3sl4co1l:
I recall measuring a random 2N4401 in the low nA.  It was a cold day, YMMV. :)

If it's not on the datasheet, you have to test it yourself.  Fine for breadboarding, or small run test equipment, say.  Not so great for production.

Again, jellybeans aren't tested for leakage, because it's slow -- expensive to test!  There may be special-purpose designations which are, but they'll be expensive for that reason (and also the much smaller quantity of product being moved).

Tim

Cerebus:

--- Quote from: T3sl4co1l on October 19, 2017, 09:10:05 pm ---If it's not on the datasheet, you have to test it yourself.  Fine for breadboarding, or small run test equipment, say.  Not so great for production.

--- End quote ---

But doable nevertheless. The HP/Agilent/Keysight 34401A had a selected JFET* in the input amplifier and they made 25,000 a year of the suckers.

*Q104, selected for a given range of VGS at an IDS of 1.36 mA.

SeanB:
Simple reason they do not change the spec is because the specification is for a MINIMUM requirement, that the transistor is guaranteed to meet when manufactured. That your device you bought is so much better is moot, you are buying one that gets that minimum spec exceeded.

As to different devices getting different part numbers, randomly opened the NS small signal transistor book, and looked at process 63, PNP medium power device. There the same die can be put into 5 different packages, and be variously a 2N2905A, 2N2907A, 2N4403, 2N3702, 2N3645 or a 2N4143.

Then you get the interesting ones, like process 59, a dual small signal MOSFET in TO99 package that is a whole series of FM3954 or FM1100 series.

Then process 1, which is graded into various power parts, including the venerable 2N3055.

Fun one is a MPQ6502, which is not a processor.

Cerebus:
Wouldn't life be easier if, instead of the JEDEC/whatever part numbering scheme evolving, we'd had something like the National book. Here's the set of dies, here's the parameters we actually test and here's the bins we put them into and the part numbers for those bins.

I still find myself going to the (defunct) National databook to find a suitable part from time to time just because the layout by process makes it easier to navigate.

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