About Ge OC140 (CV7112 black glass military germanium)

[aron]

It was very interesting when I found out that the OC140/CV7112 was symmetrical and that the dot could be emitter or collector! I started testing and lo and behold, it's true. What I have found is that if the dot is emitter, then the gain is usually less than if the dot is used as collector. If the dot is used as the collector, most of the transistors fall right into the desired Fuzz Face range. If you purchase the Ge from me, then on the package, there might be • = c which means it was tested with the dot as collector. If there's no writing like this, that means the dot was used as emitter. In this case, you could flip the transistor around and use the dot as collector for more gain.

What a useful transistor and most are low leakage.

Aron

[rockgardenlove]

Hehe, I've been playing with the ones you sent me, and I've noticed the same thing.  Cool!

[Dragonfly]

so essentially, if you had one that tested say, in the fuzz face range, its likely that you could "turn it around" and be in the rangemaster range ?

interesting ...

[aron]

I never thought about it that way. You are right.

[Gilles C]

After playing a bit with these specific transistors and reading about transistors, here is a place where this is mentioned

http://en.wikipedia.org/wiki/Bipolar_junction_transistor

"Reverse-active (or inverse-active or inverted): By reversing the biasing conditions of the forward-active region, a bipolar transistor goes into reverse-active mode. In this mode, the emitter and collector regions switch roles. Since most BJTs are designed to maximise current gain in forward-active mode, the βf in inverted mode is several (2 - 3 for the ordinary germanium transistor) times smaller. This transistor mode is seldom used, usually being considered only for failsafe conditions and some types of bipolar logic"

Gilles

[km-r]

geesh... out of the topic, where do you get all these stuff??

[aron]

Google. I found this as well a while ago. Pretty cool!