Wow...Germanium transistors really ARE a crapshoot.

[brad]

I just finished testing 10 of those blue spot AC127 NPN germs off eBay.

Out of the 10:
2 leaked 800uA+
4 leaked 600uA+
4 leaked 420uA and had a hfe between 40-50

So I got 6 new diodes and 4 kinda ok transistors!

I also bought 5 AC125 PNP germs off eBay from minifux1

Out of 5:
4 leaked 600uA+
1 leaked 550uA

So I basically got 5 new diodes!  :shock:

Are any of the PNPs even worth considering using?  Next time I'll just buy my germs from Smallbear  

[Arno van der Heijden]

Hmmm... interesting...

I also bought 5 AC125 from the same seller.

2x 200uA~
3x 300uA+

One of them has a gain of 80, the other four are between 120-150.
These results are really different from yours.  

I've yet have to test 5 OC76...

[ESPguitar]

:lol:

[hairyandy]

I've bought quite a few off Ebay, and from minifux1 as well, and I've had pretty good results.  I just check for hfe with my DMM.  I understand that this doesn't account for or measure leakage but I figure that if the hfe is very high or very low then I just don't use them.  I've been building mostly Rangemasters and I've had great luck with OC44's, OC76's, OC47's, OC45's and OC71's from Ebay.  I tend to come more from the "if it sounds good who really cares?" school and usually I can't tell a whole lot of difference with most of the trannys that I buy.  For my Rangemasters, if the hfe is over 50 and under 130-ish they pretty much all sound similar.  Just try popping some of those leaky ones in a pedal and see what they do.  Granted, your mileage may vary depending on the circuits you're building, but you never know?

[Karmasound]

I've bought from the same seller also.

About 98% of the one I got were too leaky.

I wonder if maybe he doesn't presort them and sell the ones he doesn't want on ebay.?


I will say that he replaced an order when the first one got lost in the mail.

[Karmasound]

I've bought quite a few off Ebay, and from minifux1 as well, and I've had pretty good results.  I just check for hfe with my DMM.  I understand that this doesn't account for or measure leakage but I figure that if the hfe is very high or very low then I just don't use them.  I've been building mostly Rangemasters and I've had great luck with OC44's, OC76's, OC47's, OC45's and OC71's from Ebay.  I tend to come more from the "if it sounds good who really cares?" school and usually I can't tell a whole lot of difference with most of the trannys that I buy.  For my Rangemasters, if the hfe is over 50 and under 130-ish they pretty much all sound similar.  Just try popping some of those leaky ones in a pedal and see what they do.  Granted, your mileage may vary depending on the circuits you're building, but you never know?

I've done the same thing also.

But when you get ones that are too leaky they might sound good one minute then the next they sound like crap.

I've had some that I biased up and started playing and within one minute sounded dreadful.

I've noticed that when they drift up  they don't sound as bad.

But when they drift under 4.5v  I can tell as soon as they do and I can't stand the way they sound then. :cry:

[Fret Wire]

That's about normal really.  

First, most Ebay Ge lots are leftovers from lots that have already been picked through for the good ones. It's always a crap shoot buying untested Ge's, even worse on Ebay.

Second, Ge transistors were very inconsistant when they were being manufactured. They weren't that great when they were fresh: 30-40 yrs older, they are even worse.

Alot of the Euro trannys such as the AC128, 125, 127, the OC75, OC76, etc. have bad reps now for fx use. I think it's mostly due to their manufacturing methods that many deteriorate faster than the Japanese or American Ge's. That said, if you have AC's or whatever that are low leakage, proper gain, and are stable, they will sound very good. You just don't get as many that do. But the AC types shouldn't all be dismissed as some people do.

The Japanese and American trannys seem to survive time better, maybe due to tighter tolorances during manufacture? I've had great luck with 70's vintage Texas Instuments trannys. They are usually always stable, as well as low leakage.

Stability is just as important as gain and leakage. When you test certain trannys, you'll see that their readings never sit still even though the gain and leakage are in the right range. You can have a transistor that is low leakage, but still unstable.  They are basically dying, for lack of a better word. They will never bias up as good, or sound as good as a stable pair will. Any Ge that is stable will sound good even if the gain is a little higher or lower than normal. People who just plug in trannys and go with a pair that sounds good probably have hit on a good stable pair.

[brad]

Thanks for the informative replies!  

You really can see the DMM readings change before your eyes with the leaky germs...it's like watching Wheel of Fortune!

[H.Manback]

You can even take your temperature with them..... although sitting on a breadboard might look a bit silly

[brad]

In that case, I wonder what holding one up to a lightbulb would do!  :lol:

I don't know if I'd want to bid the $25 I've seen 5x black glass OC44s go for.  Even if you get one good unit out of it, that's a very expensive transistor!

[dubs]

What about cv7003? They are a miltary version of oc44 so I figure they would be less leaky?
I just ordered some  cheap,

[Doug_H]

First "lot" of Ge transistors I bought were a handful I grabbed at the local surplus place. Don't remember the price but they were a good deal. They look like power transistors because they are pretty big and in a heavy-duty pkg. I used one temporarily in my easy face. It was 'okay', that's it. All the difference in the world when I replaced it with a small-signal low-leakage piece. Anyway, finally got around to testing them and they all leaked in the mA range :!: . Tried breadboarding a rangemaster with them and they were useless. Not very useful for me, maybe okay for diodes.

We all live and learn....

Doug

[R.G.]

You can also run into some real horror stories. Since there isn't much new manufacture of germanium transistors, the stocks that are left have often been picked over before. Sometimes you'll get a batch that were left when someone else selected out the low-leakage devices. That batch will show 100% high leakage.

How do I know this???

:cry:

[Karmasound]

Surely there is enough of a demand from the music world to make a new batch of these things.

Low leakage quailty built devices.


I mean they do that for tubes

[Torchy]

ZV seems to do ok for his FuzzFactory transistors ... wonder what he uses ?

[brad]

ZV seems to do ok for his FuzzFactory transistors ... wonder what he uses ?

I've wondered this myself.  I'd imagine the Fuzz Factory is probably more resilient towards inconsistant transistor specs because the bias knob is part of the effect.

Surely there is enough of a demand from the music world to make a new batch of these things.

Low leakage quailty built devices.

I mean they do that for tubes

Dunlop managed to get new germaniums manufactured didn't they?  Perhaps we should start a petition!  

[R.G.]

Germanium Power Devices is a company that makes current day germaniums. Their business is primarily replacement stock for older ... military... equipment and some ...aerospace... stuff that uses germanium and can't be redesigned. They can make essentially any USA (2N....) device and many others.

Back when I was playing shopkeeper, I had them quote me for some new-manufacture germanium devices. They have some stock, which is quite expensive. The will make a run of them for you at a given price per part starting at 1000 pieces. That's cheaper, but still not all that affordable.

I suspect there are other places, but the rules of economics apply. The payment up front has to be enough to pay for them to shove a wafer of germanium into the ovens and package up the parts, and enough larger than that to give them a reason to do that cheerfully.  It's several thousand bucks to sit down at that table.

I passed. It's still cheaper to find old stocks. So I bought up some old stocks. The remainders are still in my parts archives.

I would guess that this is the path that every germanium using maker goes through. With enough volume, it makes sense to get them made. I believe that GPD made the devices for Dunlop, but I have only intuition and innuendo to support that.