Zero Leakage Germanium Transistors?

[claytushaywood]

Is there sucha thing?  Or are these actually PNP silicons?

[JakeFuzz]

Hmmm, probably silicon. Germaniums usually have some leakage. A lot of the later germaniums that use an alloy process have very low leakage (Russian trannies) but you can still measure it.

[sgmezei]

Having measured over 80 germanium (russian) trannies this week I can say this:

They all have some leakage, although minimal. The ones I got from Small Bear have had more leakage for sure but still in the useable range for sure.

Since I had my breadboard set up, I tested a couple silicons as well. These showed no leakage.....

[dwstanford]

Ive had some with lower leakage read as zero hfe on some testers, but chances are if all are reading zero consistantly, you may have silicons.

[jrod]

The transistors in question are ones that I measured and offered to sell.

I am using a Peak Atlas and a large number of these 2N1305's I have read "0" leakage, though some do show a very small amount from like 5uA to 40uA.

The only other time I have seen this is with Russian germaniums.

So, after some private messaging and reading comments on this thread I am wondering if these devices may be faulty.

What I think is happening is that the leakage is just very low in these devices. The Peak Atlas displays leakage in mA, where RG Keen's suggestions for Fuzz Face devices are referred to in uA. So, I am thinking that the Peak Atlas just isn't picking it up. In other words, if there is actually 5uA of leakage, then the Peak Atlas would show 0.005mA, which may be outside of parameters of the meter to display. So, perhaps anything under 10uA will read 0.00mA leakage on the tester. Now, I would imagine that if I tested the same device on RG Keens test circuit, I would see a little leakage, but not much. I have not tested these particular devices using both methods, but may set up RG Keens circuit this weekend if I have time and experiment.

One of the cool features about the Peak Atlas is that it will tell you if the device being tested is ge or si and NPN or PNP. The 2N1305's DO show they are PNP germanium on the Peak Atlas.

I don't know. What do you guys think? Anyone here with a better understanding of the Peak Atlas works that may be able to shed some light here?

Thanks!
Jared

[JakeFuzz]

Hmmm, yeah I have some 2n1304's and 2n1306's that have very little leakage (most close to 20-30uA). They sound good, very much like the 2N404's I have. I would just throw those in a simple FF circuit and see how they sound. What are the gains on that batch and how many do you have? I may be interested in picking up a few. Thanks.

[culturejam]

What I think is happening is that the leakage is just very low in these devices. The Peak Atlas displays leakage in mA, where RG Keen's suggestions for Fuzz Face devices are referred to in uA. So, I am thinking that the Peak Atlas just isn't picking it up.

I believe you are correct.

I've had a some germanium trannies actually read as silicon on the DCA. The is because the DCA uses base-emitter voltage drop to determine silicon vs germanium. It will read "silicon" for anything higher than 0.39v. But there are some germanium devices that have as high as 0.45v drop. So it's not perfect, but it's usually right. If you have doubts, look at the base-emitter voltage drop that the Atlas displays. If it's 0.5v or less, it's almost certainly germanium.

One thing I've noticed is that the DCA always measures germanium diodes incorrectly. Try it yourself and then compare to any other DMM. The DCA shows the drop to be about 0.6v on germanium. I have no idea why.

[jrod]

Thanks for the info, Culturejam.

I haven't measure a lot diodes with it, but I will check it out. I usually use my DMM for that anyway.

Looks like I DO have a good batch of germs here! They measure in the 60's - 180 hfe with the highest leakage being 100uA and most >10uA.

Glad I have that solved!

Thanks guys!

[sgmezei]

That's awesome dude. Let us know how they sound. And then where you got them........ Hahahah.

[cjkbug]

Hmmm, probably silicon. Germaniums usually have some leakage. A lot of the later germaniums that use an alloy process have very low leakage (Russian trannies) but you can still measure it.

I know that a lot of russian transistors have an internal shunt resistor witch makes them appear to have no leakage when measured