why transistor makers do not label the "B" "E" and "C' legs on their transistors?

Question

I think, at least, they can use different length of legs for identifications. e.g. short leg for emittor, long leg for collector.

Answer 1

Too small.

For a small signal surface mount transistor, the package is sot23.

That is roughly a size of two grain of rice. It has to have device marking. No room for it. Plus with that small marking, you may need magnifying glass to see.

Answer 2

I have actually come across a few transistors that were labeled, usually only "e" or "c", or more often with only a dot at the emitter terminal. However, transistor manufacturers provide data sheets for their transistors, assuming that anyone who uses them in a design will need to know its parameters and ratings. Included in those data sheets is a diagram showing pinout, so there is no need to label the pins.

Answer 3

They assume that the end user is able to determine the Style of the Transistor case and refer to a chart to determine the B C E pinouts.

Answer 4

The first two answers are good. Remember, too, that as long as it's not MOS in construction, you can always use an ohmmeter to ring it out as if it were a couple of diodes. Assuming you know whether it's pnp or npn, that will let you find the emitter, base and collector legs.

Answer 5

they are too small. and its common understanding and also reduces cost. and avoids confusion in the naming of the transistor