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help identify these transistors

Hi all,

A few years ago (1995) I bought a scoop of plastic transistors from a company called "electronic goldmine". I am unable to get any data on these transistors.

Can anyone please identify these transistors?

All are plastic, small signal packages, I think to-92 type.

  1. national semiconductor. marking "615-3"

  1. national semiconductor. marking "2553"

  2. national semiconductor. marking "435-1"

In addition, all of these also have another number like "827", "826", but I think they are the year of marking and month/quarter, etc. Apart from these two, there is nothing else printed on the device.

Curioucly, there is a three color band coding on the back of the device, I dnot know if this indicated a current gain factor or something.

Thanks in advance, Sreenath

Reply to
sreenath
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Reply to
Mike Berger

Hi, thanks for the tips. I tried using the color codes,and could not find meaningful results.

There are three colors on the back of the transistor. Also, after I don't have any way of knowing what the preceding type would be, like

2N, MPS, 2SC, etc.

I am really consufed. Don't know why a company like National semiconductors does like this- not printing the full device type on the transistor.

thanks, Sreenath

Mike Berger wrote:

Reply to
sreenath

If they're National, they're probably 2N numbers.

sreenath wrote:

Reply to
Mike Berger

sreenath schrieb:

There is a reason: if those transistors were produced with some special specifications for one single customer. In common those transistors have uncommon type numbers.

On the other hand, there may be a solution for your problem. When you look into an old NS transistor data book, you won't find detailed data for type numbers - you'll find them for processes! Of course there is a table with some 'coarse' data for National's transistor types (like

2N2222), but details can be found under "process 19". Perhaps the colour marking corresponds to the number of the process.

HTH

Reinhard

Reply to
Reinhard Zwirner

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