Vintage Transistors

[rlopes]

Hello.
I need your fuzz expertise.
Today i found some old transistors in a local store. Here is a list of them:

- OC 42 X10
- OC 44 X2
- OC 45 X5
- OC 70 X1
- OC 71 X6
- OC 74 X2
- OC 75 x1
- OC 81 X1
- OC139 X5
- OC140 X10
- AC124 X6
- AC127 X2
- AC128 X10
- AC187 X3


I have to test them for gain and leakage but i need to know what values of gain/leakage are good or bad to use in a fuzz and also what kind of fuzzes i can build with these type of transistors.
Any help will be appreciated.

[Scruffie]

Hello.
I need your fuzz expertise.
Today i found some old transistors in a local store. Here is a list of them:

- OC 42 X10
- OC 44 X2
- OC 45 X5
- OC 70 X1
- OC 71 X6
- OC 74 X2
- OC 75 x1
- OC 81 X1
- OC139 X5
- OC140 X10
- AC124 X6
- AC127 X2
- AC128 X10
- AC187 X3


I have to test them for gain and leakage but i need to know what values of gain/leakage are good or bad to use in a fuzz and also what kind of fuzzes i can build with these type of transistors.
Any help will be appreciated.

Nice Haul, recognise a lot of the names there.

The 71 & 44 are classic Rangemaster Trannies, People use AC128s for Fuzz Faces (even though after some digging no one ever found a unit that used them) the 81 and 75 could be mixed with something else there for a Tone Bender MkII but to be honest, that's just 'standard' they'll probably all be good for fuzzes.

Fuzz Faces & Rangemaster will have less noise with the lowest leakages 100mA is good gain wise is personal preferences, around 70-120hFe though for both, anything over 500mA is questionable but will probably be good (MkIIs need leakage to work) 1A and over is probably bad.

Really though the best thing to do will be get a breadboard and experiment for what you like best rather than going by pure numbers and what's considered 'correct' transistor, gain or leakage wise.

Some guys better with germs can probably help you with the other stuff there for what they like.

[midwayfair]

You might find some subtle variations in sound (JakeFuzz can hear those differences better than I can), but the best thing you can do is test them for leakage and gain, put them in marked bags, and then breadboard until you're silly.

Be sure to look up the datasheets to find out if they're NPN or PNP.

I'll make a standing offer to buy any of the black glass NPNs that are "too low" to use in a Fuzz Face or Rangemaster if you don't like them. (E.g. those 139s and some of the 140s.) Seriously, anything 60hfe and below.

Er.... anyway, just my opinions:
1) for the PNPs that are really low gain (below 50), use them for Q2 in a PNP Buzzaround and for the germanium in a Percollator. Those are really important places to have less gain for best behavior in my experience.

2) For anything really leaky, using them as the third transistor in any 3-tranny fuzz will work.

Remember that the actual gain in some cases is irrelevant. You can make a fuzz face work properly with two transistors of hfe 40. I have one with two low-leakage 60 hfe transistors and not only does it have a wall of fuzz, but it's one of the loudest fuzz faces I've made and it needed a pregain pot to actually clean up properly.

The only things that really matter are whether the leakage is going to cause too much noise. Pretty much everything else can be dealt with by changing biasing resistors and tinkering with some other stuff in the circuit.

[icecycle66]

That's awesome.  what kind of stores are you going to that just has a bunch of old transistors laying around?

[JakeFuzz]

That's awesome.  what kind of stores are you going to that just has a bunch of old transistors laying around?

Seriously man. What store is this? I've some across some old radio and TV repair places that have a small stock like that but nowhere near that selection. Those are all good types BTW.

If the store folks let you test for gain and leakage I would get anything with gain higher than 50. I've been meaning to do a Darlington type pair or the complementary pair (Sziklai) with really low gain devices (10 and 10) but just haven't gotten around to it. Steve from smallbear says they sound good so the real low gains devices might be a good bet as well. As for leakage I find that I can use anything below 700uA. Ive tested above that and things start to get really weird. Typically your really high gain devices will have higher leakage as well (but not always like my GET's with 200+ gain and <200uA leakage).

Don't forget to test some of those devices backwards. Many times one alloy pellet will have been larger than another during the thermal diffusion process but sometimes they were symmetric which makes the reverse gains just as likely to be good. I have found this is particularly true with the OC types. Test everything both ways. 

As for price the going rate is around $5-10 for each good device depending on rarity (NPN and high gain is usually more). I have found batches of untested for 0.4-1.00 each. I would day anywhere in between is a decent deal. And if you ever feel like offloading some good ones I would be in for some of those. Good luck.

[jeffaroo]

breadboard time ! ! !

[jeffaroo]

maybe a fuzz with a half dozen switches on it !   

[Pvt. Parts]

What is the price? if they are cheap, just get em all and sell them her 

[stecykmi]

clearly by the responses in this topic, you should realize that you found a small treasure trove with those trannys. happy fuzzing.

[rlopes]

It seems i really found a little "treasure" yesterday (and i've only been in the store for 20 min.). They still have a lot of old stuff. I didn't have the chance to test them so i bought as much as i could. Maybe i can find even more i just need to go there again with more free time.
Now i really have to test them (i don't have any proper device to test the transistors so i'm tinking of building a small transistor tester as said by R.G. Keen).
I can search in the store any specific item if any of you want. Just drop me a message and i see what i can find.
Thanks to all for your advices.

[DutchMF]

Well, the transistors are great find already, so if I where you, buy as much as you can! If they have a really huge stash of the things, we might have to rally up some cash so you can buy every last one they have. Next you could check if they have some nice mojo capacitors, carbon comp resistors, vintage cloth covered wire, nice old knobs..... My advice is to buy as much as you can afford (and I mean within an inch of not being able to pay the rent..... just kidding, please don't!  ) I'm quite sure that whatever you don't want/need yourself will find a happy home through this forum! Congrats on the treasure!

Paul

[rlopes]

Thanks 
I have to go there again to see if i find some more old stuff.

[hammerheadmusicman]

i would love to take some of those off your hands if they are deemed useful by the guys above! If you were to pick some up, give me a shout, and we'll strike a deal

George

[rlopes]

Yesterday i came back to the store where i bought the vintage transistors and i spoke to the owner. I told him i was looking for some old transistors and he told me he had lots of old stuff (transistors, capacitors, resistors etc) in his own house, that came from an old electronics store that was going to close. He bought all the store's stock and stored it in his garage. He only brought some of the old stuff to his current store because no one is looking for that old components anymore. He doesn't know exactly what type of transistors he has but he told me that i can go tho his house and search in his stock to see if i find something i'm looking for. I hope i find some good stuff

[DutchMF]

You lucky dog! Buy everything he has, and then, with a mild, mild upcharge, sell it to us! You definitely hit the jackpot!

Paul