4 legged germanium

[drgonzo1969]

I have these NPN germanium transistors I want to try in my dizzy elk pcb but the transistors have four legs in stead of three. It looks like maybe it has 2 collectors? How should I plug this sucker in?

 

[Silver Blues]

Fourth leg is the "body". In some circuits, this is just tied to the emitter - try that first.

 

[chris.knudson]

I'm not sure, but I think the 4th leg is ground. Pull the data sheet (although I suspect it's in Russian).

 

[music6000]

I believe it's attached to the body so no need for it in your application, chop chop!
Do you have a transistor tester, best way to check!

 

[Mcknib]

Just continuity check it to the transistor body they are normally ground if it beeps it's ground and you can just snip it off as @music6000 said

 

[Ginsly]

I've come across this a couple times... So as long as the fourth leg has continuity with the body you can always cut it off? There's never a need to connect it to Ground somewhere?

 

[thomasbe86]

Those are the GT311 russian ones, datasheet is here, ChatGPT is always happy translating these.

Got a bunch of the i series (the reverse N) about a decade ago for all NPN versions of oldies.

Rarely found such high hFE for germanium NPNs (up to 500). Somehow they sell cheap as PNP, I believe because of a typo on alltransistors.com Body leg is ground, body of the transistor is then grounded and helps with isolating from EMI and power dissipation... You don't have to ground it but it is recommended.

Russian manufacturers carried on with germanium throughout the 90's while most western manufacturers had completely moved on to Silicon, this one series (GT...) is a good example on how they kept pushing with inovation with a - soon to be - obsolete technology.
I think I remember they also have absolutely no leakage whatsoever.

 

[juice886]

btw, soviet JFETs also have same additional 'leg'.

 

[jwin615]

Off topic but I wonder what adverse effects continuing to use Ge transistors had. Like, on a rare 100°F day, could certain fighter jets not fly because all the transistors drifted too much? Would boomboxes get louder when you took them outside and they sat in the sun? Did clocks run slower in the winter? Could they only launch a Spudnik in certain temperatures? Did Moscow muff massagers speed up from the body temp? I know they had Si bjts too. It's just hunerous to think about. For me anyway.

 

[CheapSuitG]

That sounds like the start of a joke. "So a 4 legged germanium walks in to a bar....."

 

[Stickman393]

I'd like to introduce you to my friend, Mr Faraday.

He has a cage that is quite useful in electronics applications.