# Identifying Transistors

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#### TheNewGuy

##### Member
I have a bag full of transistors like this one:

http://www.musanim.com/mam/transistor.jpg

how do I go about finding out which prong is which? Emitter, base, ect..

The transistors have no markings on them!?

Thanks Everyone

#### Hero999

##### Banned
The BC108 is obsolete, where do you get them from?

#### TheNewGuy

##### Member
The transistors I have now, have that shape and no tag. I'll take a picture of it if you guys want. No markings either!

I got a bag of electrical components from a relative of mine, when he heard that I had a project going so he gave it to me. (I'm building an amplifier with an LM386 IC). And half of the entire bag are these transistors.

I thought because I had so many, maby someone could tell me where I could put them to good use? Or if I could use them in my next projects.

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#### Hero999

##### Banned
Perhaps you should get your eyes tested then.

Here's a close-up with the tag circled in red.

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#### TheNewGuy

##### Member
There are no markings on it though.

Is it a BC108?

#### TheNewGuy

##### Member
Could it just be a standard transistor?

#### Nigel Goodwin

##### Super Moderator
Could it just be a standard transistor?
What's a 'standard transistor'?.

#### Bob Scott

##### New Member
Ooo-boy!

I have some transistors like that. Circa 1963 vintage, Germanium, TO-5 case with ceramic bottom, springy gold over steel leads, and obsolete decades ago.

Standard pinout bottom view starting from the tab going clockwise, just like tube/valve pins: 1: emitter, 2: base, 3: collector. Use a DMM with a junction tester to find out whether the junction voltages are Ge or Si.

I would not use them for anything.

Bob

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#### Mr RB

##### Well-Known Member
Tag is always the emitter, base is always in the middle. The old metal cans are easier to pinout than the TO-92 mess.

Generally germaniums don't have the tag, but if they are germanium they are collectable. People like to use them to build exact reproductions of old guitar effects units etc.

#### Hero999

##### Banned
I like germanium transistors because they have a lower on-voltage they can work from ridiculously low voltages which is handy for single cell AA circuits.

#### Brevor

##### Member
Ask the person who gave them to you, If he doesn't know what they are then just throw them away! Transistors are cheap and these are probably not what you need for your project anyway.

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#### TheNewGuy

##### Member
Bob Scott said:
I have some transistors like that. Circa 1963 vintage, Germanium, TO-5 case with ceramic bottom, springy gold over steel leads, and obsolete decades ago.
I have like a billion of these things!

Are there any use for them at all? Possibly any low voltage applications?

Thanks alot guys! I really appreciate it.

I also got some regular transistors with different model numbers. I'll sort through them and post some model numbers.

#### mneary

##### New Member
They are obsolete, but they should still work. On the other hand, they have somewhat different characteristics from silicon transistors. When silicon transistors became available at low cost, most of us put our germanium transistors into the drawer or waste bin.

1) Germanium tend to have significant collector leakage, whereas we tend to ignore this in silicon designs. The leakage has a temperature coefficient that is a problem even at moderate temperatures.

2) Their base-emitter voltage is about 0.2V. Silicon is nominally 0.65V. This isn't really a problem, it's just different. As mentioned, some special circuits use this feature.

3) Most germanium transistors are useless above 85 degrees C whereas many silicon transistors are useful up to 175 Celsius. Storage temperature of 2N1304 is limited to 100 C!!!

4) The maximum VCE tends to be lower. Economy germanium transistors were 25V, while economy silicon transistors are 40-60V.

5) Frequency response (FT) of general-purpose germanium transistors were in the neighborhood of 1-10 MHz. (Specials were made for RF, but they were expensive.) Cheap silicon transistors are usually 300 MHz.

You might look up 2N1304 and 2N1305 to see the characteristics of popular mid-60's germanium transistors.

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#### arunb

##### Member
try the local museum

#### Mr RB

##### Well-Known Member
If they are germanium, sell them on ebay for big \$.

#### hemanthemma

##### New Member
The best way to identify a transistor is by using a multimeter.Put the multimeter on check mode.Check the resistance between Emitter/Base and Collector/Base.Check on the internet the transistor having the similar resistance.Although there are various transistors with the same specs but it might be helpful.

#### EN0

##### Member
Yes, make sure you have the Vbe drop.

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