Yep. Samey samey. The bottom numbers might be batch numbers, code dates, or sorting bins.
I think they are irrelevant to people like us but somebody wiser might fill in the proper information.

 

There can be different grading mostly in terms of hFE. Its sometimes rather attached to the model number as such.

 

That's what I meant by, "sorting bins". Sorted for best gain.
As takao said, Sometimes it is added to the model number as 2N4403A or 2N4403B
That doesn't mean A is better than B. Sometimes the manufacturer does it backwards.

 

some applications benefit from low or lower gain...

The gain is a complex parameter, among other things, largely depends on the current.

 

some applications benefit from low or lower gain...

The gain is a complex parameter, among other things, largely depends on the current.

An alphabetic suffix can mean other things as well:

On the old BC182/212 pairs, A, B and C were gain ratings while an L suffix indicated inline leads with the same pin designations as most Asian TO92 packages.

AFAICR: the A, B and C variants had the lead outs like the corners of a triangle, more or less similar to the lead spacing on the metal TO18.

Some Asian transistors have odd letter sequences, the 2SC945/2SA733 had O, P and Q (and possibly also R) for gain bands, while other makes have denoted gain bands by colours - but instead of marking the device with the actual colour, they suffix it with the first letter of the colour.

 

the ones I have for selling:

C945
P331

A big H on the backside, embossed into the epoxy

Color stamping is out of use for quite a while AFAIK

 

Cool... so I have replaced the 2 with new... er..generics... I assume in this circuit they will work.
Thanks...

 

If I recall correctly, the 2N4403 is a switching transistor with a fairly high current capability. If you replaced them with a 2N3904 type, you might have trouble. It depends entirely on the circuit which you have not revealed to us.

 

If I recall correctly, the 2N4403 is a switching transistor with a fairly high current capability. If you replaced them with a 2N3904 type, you might have trouble. It depends entirely on the circuit which you have not revealed to us.

AFAICR: The favourites for a little bit more current are; BC327/337 in Europe and 2SA1015/2SC1815 in Asia.

 

@#12

What the hell happened to this dangling participle? What did this line of transistor talk get ripped off of the original thread? And post #9 just showed up as a new post today - even though it was posted on the 27th of June.

 

@#12

What the hell happened to this dangling participle? What did this line of transistor talk get ripped off of the original thread? And post #9 just showed up as a new post today - even though it was posted on the 27th of June.

It looks like the original question disappeared. I can only chalk it up to lots of noisy website construction work going on where we can't see it. Things get misplaced, or maybe the TS deleted his post. I'm not the person to ask because I'm not on the construction crew.

IIRC the original question was a pair of used 2N4403 transistors. One had a G and one had an H in the line under the part number.