Is there a meaning to colors on a transitor?

[RAPo]

I've got a whole collection of (unclassified) transistors.
I'll know that a dot on it can mean it is a matched pair.

But I also have transistors with several colours.


Do these colours have a meaning?

[Psi]

Yes, its just the part number without the prefix, like 2N etc..
Colors are the same numbering as resistor colors. So red red red red would be 2N2222 etc...


https://www.instructables.com/From-Resistors-to-ICs-Color-Codes/

[RAPo]

Ah, thanks. That makes the classification job easier. Topline color = first digit?

[Benta]

Please show the other side of those transistors. The "colour-code" hypothesis is not really credible to me.

[floobydust]

I know those coloured stripes as ranking for h_FE or I_DSS, not the actual part number.

[RAPo]

I think you are right. There are several A06's but they have different colours

[RAPo]

Do you have more info on which colour is used for which property?

[madires]

There are also BJTs with a dab on top to indicate the hFE range.

[Jeff eelcr]

Many transistors were sorted for some spec, this is the way they were marked.
Whether they were marked by the transistor manufacturer or the company using them in manufacturing could be found out by asking the transistor manufacturer if possable, if not, I do not know of another way.
Although not as common this process is still used today.
Jeff

[RoGeorge]

There was a time when Ge transistors where binned by beta, or by fT, and each category was a dot of different color.

[Benta]

MPSA06... I remember those.
You have two different things here:
1: the thin horizontal stripes are production codes for lot/year/week whatever. Done by Motorola.
2: the "colour blobs" can be anything, but certainly not OEM.

[Kleinstein]

Japanese JFETs (e.g. 2SK...) often come with IDSS grading via a color code, even with the same system used on different parts. With modern part the color may have changed to a letter code representing the color (e.g. R, O  Y GR BL ) not just for ordering.