Silicon FF transistors

[bonehead1972]

Hi guys,


Just took apart some old junk and got a few silicon trannies to92. PNP. Hfe within the 85-135 range. They have 3 color bands on the back side and no name/type on the front.That's cool...

I am wondering if someone could help me to identify that type of transistors.
Thanks:)

[Marcos - Munky]

With no marks at all, it's basically impossible to identify them.

[bonehead1972]

Thanks for your reply!
Ok..under a magnifying glass there is something barely readable...most likely  bc327 or bc187.  Breadborded the thing, voltages are good and sounds good
Cheers!

[willienillie]

I've never been able to make any sense of the colored stripes on transistors.  It doesn't correspond to the type, nor any particular spec as far as I can tell.  Might be completely different from one manufacturer to the next.

[R.G.]

Let me add to what willienillie said: the color codes may be almost anything. They probably meant something at one time to either the manufacturer or the company that bought a bunch of specially selected transistors. But any meaning would have been local to that manufacturer or buyer, and is probably lost.

[Rob Strand]

At the end of the day chuck them in the circuit and trim the value of the resistor  on Q2's collector to get a collector voltage of about 4.8V and it will pretty much be there.  Beyond that you can play with input cap values and add small caps across the BC junctions of the transistors.

FWIW, you can narrow down the transistors from the pin out,



That and the gain probably narrows it down to several hundred possible options  .

[11-90-an]

Have you checked the pinouts with a MM?

[bonehead1972]

Thanks for your help guys!
  to summarize..what I was able to see under magnifying glass, pinout and gain ranges specified..They are bc327.
I imeditely got q1c- 1.39v, q2c -4.84v with no resistor tweaks whatsoever and sounds good:)

[Steben]

BC187 have a higher minimum hfe (140) listed than BC327 (100).
A BC327-16 is even selected for a hfe between 100 and 250. This may well match with what you have.
I'ld say they are on paper ideal FF silicon trannies.

[bonehead1972]

Yes...they all measured  within 85-145 hfe range. And they sound good