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Author Topic: Identity of these transistors  (Read 1366 times)
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elecgreg
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« on: June 06, 2011, 09:55:00 09:55 »

Hi everyone, I'm looking for help in finding out what these transistors are. I was given several hundred of them so thought I shall see what they are and use them.

I have found the part numbers listed on many sites (mainly Asian) but no idea of specifications. I have emailed a few of the places that list them but have had no response.

What I have tested with the things I have access to is break down voltage (~480 Vce) and the Hfe, it varies between about 7 and 50 (7 at Ib of 2amps, Ic of 14, Vce ~5V)

Does anyone recognize the part numbering system on these? I'd like to find out what they are for sure.

I was told they are from power supplies for telephone exchange equipment.

Is this a custom labeled part, see the attached photos for clues.

Thanks in advance, elecgreg
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solutions
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« Reply #1 on: June 06, 2011, 07:44:51 19:44 »

The date codes appear to be from 1982 and 1984.  If you can find out who made the telecom gear that'll tell you if it was captive or not.

A lot of semiconductors, even captives, will have the mfr, logo, or the part number marked on the silicon (germanium?) in top metal - you might want to stick it under a microscope for further clues if nobody comes up with anything.
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elecgreg
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« Reply #2 on: June 07, 2011, 06:11:00 06:11 »

Thanks Solutions, I will give a microscope a go and see what I can see. I quizzed the person that I got these from, the fact that they came from a phone exchange was scratching his memory, who made these was not known. By the feel of the conversation if they even came from a phone exchange I can't be 100% sure off.

Do manufactures get custom made devices and label them or is it common place to custom label an off the shelf part?

Does the die size and bond wires give much away? Compared to a 2n3055 it looks very chunky, and I mean a genuine 2n3055, not a Chinese ebay one ;-)

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elecgreg
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« Reply #3 on: June 07, 2011, 11:46:08 11:46 »

Hi All,

here is a photo of the die, what scale should I be looking at for a logo?

Thanks,

elecgreg
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solutions
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« Reply #4 on: June 07, 2011, 05:26:41 17:26 »

Nothing there - they used ALL the metal for contacts..the miserable cheapskates :-)

Usually, we'll put logos and copyrights on a die on top metal.  Some entertaining examples (if you're a geek, anyway) here, starting 1/3 of the way down at "A Dog's Life" - sad that they have never heard of THUMBNAILS: http://micro.magnet.fsu.edu/creatures/

Back in the early 80's it was not unusual for GEC, Marconi, AT&T, and other telecom guys to make their own transistors, so all you'll find in that case is an internal part number that even the internal guys had a hard time finding specs for.

I'd say you spend some time on a dozen or so on a curve tracer, characterize them (which is what we do in the industry anyway), and call it a day.  The silence on this query is deafening - I'd have thought one of the old timers woudl come forward on this one for you.

Now you need to spend a few thousand dollars building something for these supposedly FREE devices...

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elecgreg
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« Reply #5 on: June 07, 2011, 09:05:55 21:05 »

Hi Solutions,

thanks for the information and Link, one of the guys at my work put small logo on a PCB, a few 1000 of them got out before he was told that is non standard and to remove it! Shame we don't make our own chips!  
As I don't have (or have access to) a curve tracer my methodical testing will have to do.
Would anyone like to have a guess at ratings of this, if such a thing can be done by looking at it?
Maybe I can use them as an pass element or something in a linear PSU?
Hopefully someone recognizes something about them, my mother was teaching me to write my name when these were made!!
The heatsink has MEXICO stamped on it if that helps, and danger live. I guess these could have been primary switches in a SMPS?


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« Reply #6 on: June 07, 2011, 11:57:13 23:57 »

They may be a GPO type, Made by Automatic Telephone Co. and Mullard made a lot of Transistors for them, probably equivalent to OC16. However, GPO types are usually found with a PO number. or maybe the later AD149 transistor.
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« Reply #7 on: June 08, 2011, 03:14:49 15:14 »

here is a cheap curve tracer if your interested

http://www.circuit-ed.com/CT100a.htm
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