NPN silicon transistors that sit right around 400 hfe?

[skiraly017]

Mouser allows me to search by minimum and spits back the usual suspects...2N500, 2N5089, etc. but those have a tendency to be much higher. Does anyone know of some transistors that seem to sit in the 400 to 450 range fairly consistently? Thanks.

[5thumbs]

Not that I can recommend and have you find the same hFE right out of the (shipping) box.  I've found that, once I find a transistor model I'm comfortable with spec-wise, I have to "audition" a lot of samples of that transistor model (via DMM) to get a sub-population of them that are within spec for what I need.  I suspect you'll need to audition some NPNs yourself to find what you need hFE-wise.

That aside, you've mentioned a few of the usual "first choice" NPNs I'd suggest...2N5088, 2N5089, etc.  But I was wondering why you didn't mention the 2N3904, which is usually a 100-300 hFE NPN, but you might find odd high-hFE 2N3904 examples that are closer to your spec.  (Everytime I buy transistors, I *always* get some that are way out of spec, both high and low.  If you buy them by the 100s, you'll get enough of these "oddballs" that you can get enough in a given sub-grouping for your project.)

Hopefully someone else will have a magic NPN tranny that meets your requirement, but if not, that's what I suggest to find your match.

Good luck!

[skiraly017]

2N5088/89's seen to hang around in the 800+ range while the 2N3904's fall into the 200 to 300 range (as you mentioned). All of these seem to fall into theses ranges pretty consistently so I was hoping that another type fell into the 400 range without having to audition bulk amounts.

[John Lyons]

I just have a couple inexpensive DMMs but my 2N5089s and 88s fall into the 400 to 500+/- hfe.
The 2N3904s I have are 150+/-


John

[skiraly017]

I just have a couple inexpensive DMMs but my 2N5089s and 88s fall into the 400 to 500+/- hfe.
The 2N3904s I have are 150+/-


John

Cool, I'll double check mine. Thanks.

[brett]

Hi
I suspect everyone will get different results because the hFE is dependent on several things, including the batch and test conditions, especially the collector current (Ic, mA). Many devices show increasing hFE as Ic goes from low (1uA) to medium (1mA), then may fall again.(check out a datasheet for a typical curve).  Older devices and power devices usually have a bigger "knee".

My DMM shows 600 to 700 for 2N5089s, and 250 to 300 for my batch of 2n3904s.

Why do you want hFE = 400? In the majority of circuits, hFE isn't important, as long as it isn't too low.  e.g. Gain in a common emitter circuit is set by the ratio of collector to emitter resistance.

For hFE = 400 you might try a PN100.  They are slightly higher hFE than a 2N3904, handle more current (500mA ??) and IIRC handle a little more heat, too.  A really useful general purpose NPN BJT.  The PN200 is the complementary PNP.
cheers

[cpm]

BC107 or BC108, 109 type "A", if i remember well are around that hfe??

[Dizzy_G]

Would BC337-40 help? Hfe rating of 250-600 and current handling of 0.5A with peak of 1A.

D_G

[petemoore]

  2n3904 around 300-400  RS Has 'em so I used some.
  5088's around 400-500    Low noise, my favorite transistor it turned out
  5089's around 800           Also low noise...higher gain.
  Really depends on what they're doing as to what/how well they do though.