The Obsolete/Obscure Transistor Info and Substitutions Thread

[newbie builder]

I'm hoping this thread will become one with a wealth of information and possibly become a sticky too. I just came across hundreds and hundreds of old transistors (FETS, Germaniums, and Silicon) and I spent time searching for every part # they had on them on this forum (at least for the germaniums so far, haven't finished sorting the rest, and there is an entire storage hanger full of more electronics stuff- transistors, tubes, capacitors, etc- that I still have to go through) and a lot of the info is scattered about, so I thought it'd be nice if we could get a large thread going in which people can give info they have about old obsolete transistors they've succesfully used and others can ask about things they have found.

Just to start out, the following are Germanium PNP transistors that are slightly less common (it would appear) that I could find from a search on here are apparently good for use in pedals (assuming of course they test well):

2n414
2n404
2n1307
2n1122
2n526
2n651a
2n652
2n652a
2n393
2n43a

Here are the Germanium NPN transistors that a search gave good info about from here:

2n1302
2n388
2n1304



And now comes the asking- I have lots and lots of transistors so I figured I'd post a list and if anybody has any info it'd be greatly appreciated. Normally I'd just test them but I'm 1) far away from home and without any equipment to test anything and 2) there's just so much stuff here to test that I'd love it if somebody might give me some info about things that do and don't work since spending hours looking at my DMM isn't my favorite thing to do.... I'd like to figure out roughly what I should and shouldn't take though because this stuff is from a deceased relative's estate and it is going to be sold, so people in my family are trying to figure out what they can sell, but I was given the o.k. to see if I could find some stuff of use before they did so.

The Germanium PNPs I haven't been able to find out stuff for yet are as follows:

2n1377
2n1478
2n109
2n226
2n247
2n1142
2n439
2n586
2n705
2n597
2n582
2n585
2n303
2n331
2n344
2n368
2n382
2n374
2n123
2n269
2n2043
2n525
2n426
2n1224
2n1516
2n2000
2n964
2n711
2n781
2n2207


Germanium NPN:

2n438
2n167
2n1605

There are probably some typos in the above #s because I did that while reading off of one computer screen while typing into another computer without checking how accurate I was, but I believe those are all o.k. I'll probably end up taking most of those home even if there isn't info on them at which point in time I'll test them and report back here to let others know what I find so that future DIY builders have a great source of info about transistors they may find in old electronics gear.

I'll probably post back later with some silicon tranny questions, but the germaniums were the ones I was most interested in so I went through those first.

Thanks in advance for the help!

[R.G.]

I hate to be a curmudgeon, but knowing everything in the world about what germanium transistors are supposed to be or might have been is not all that useful.

It's like that lyric in "The Gambler" - every hand's a winner and every hand's a loser. No matter what the numbers printed on the can say, you're still going to have to test the actual devices for gain and leakage. Since you have to test them anyway, why bother with all the lists? They don't help much. Knowing what transistors are germanium and which are silicon is a help, but there are some hard and fast rules that will substitute for a zillion pages of arcane lore. I don't believe germanium was ever put in to plastic packages, so if it's a TO-92 or a TO-220, it's silicon. That leaves only metal top hats and metal bullets. I don't think silicon was ever put into metal bullets. So that leaves only the TO-5 tophats as the only package you have to test. That's done on a DMM on a diode-resistance test scale, which tells you instantly.

It's even less useful for silicon. Good, workmanlike design with silicon makes the actual transistor parameters matter as little as possible as long as gain is enough. "Enough" is usually defined as "hfe >100", which almost all small signal devices do these days. Most bipolars in a TO-92 package will work in any circuit designed for silicon as long as you get the pins scrambled into the the right holes. There are exceptions. For very low noise design, you need a low noise amplifier transistor. Memorize "2N5088, 2N5089, MPSA18". You're done.

The idea of interactively building an encyclopedia of all transistor knowledge is seductive, but it will eat up a lot of time you could use for other things if you learn a few rules of thumb.

[MartyMart]

I have to agree with RG on this - though your enthusiasm and idea is appreciated
I'd also add a couple more to the "worth memorizing" list :
2N3904/2N3906 ( PNP ) and nice lowgain 2N2369 ( metal can )
MM.

[MetalGod]

buy a copy of Towers Transistor book - it has specs/pinouts for any transistor I've ever come across.

[Sir H C]

Some very early germaniums were put in plastic (GE's G11 comes to mind) but they are not good for much of anything but to look at.  And the cases are pretty whack.

[soulsonic]

What I don't see enough discussion of is the Japanese ones. There's some real gems there that can be salvaged out of old pocket transistor radios pretty easily.