does such thing as 'vintage' transistors exist?
« on: December 04, 2009, 06:53:25 AM »
I read somewhere in the forum that the modern equivalent of a 2N4898 is the NTE218  and for a 2N4910 the NTE175.

However, I'm wondering if it makes sense to pay a few bucks more to get the old (or 'vintage') 2N4898 and 2N4910.
Is there any difference in quality and if so, do the older parts have better quality than the new ones?
I would think that it should be the other way around... ???

thanks
w.




JohnRoberts

Re: does such thing as 'vintage' transistors exist?
« Reply #1 on: December 04, 2009, 10:00:18 AM »
In general newer will be better, as semiconductor processes have gotten better.

If the part number is different, the device may be different, in ways that might not be desirable in your circuit. A typical problem for design and manufacturing engineers is keeping designs happy with normal component production variances. Of course some designs are more sensitive to device parameters than others, and engineers try to make their circuits less sensitive to the components used when possible.

It seems the closest candidate for a vintage transistor is the 2n3055, and old work horse slow as mud, NPN. Modern offerings under the number 2n3055 are faster mainly because they don't make anything that slow any more. This can make a difference in classic applications.

Another generality is when newer parts are different, they are usually improved in some aspect, so if a circuit isn't happy with them, I'd be inclined to tweak on the circuit.

JR
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Re: does such thing as 'vintage' transistors exist?
« Reply #2 on: December 04, 2009, 10:15:02 AM »
thanks. hm, I see....
So I assume the best thing to do is (as always) buying both an original and a modern part and try them under real circumstances...


 

EmRR

Re: does such thing as 'vintage' transistors exist?
« Reply #3 on: December 04, 2009, 11:52:01 PM »
All depends on the circuit.   For instance, if you try and put modern parts in an Altec 9470A, the hfe is way too high, and it surfs the oscillations.   If you are trying to restore something, it may be critical.   I would never bet on a new design using a vintage spec part.   It's a real pain in the ass trying to keep stock on all the old crap one might need.
Best,

Doug Williams
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QUEEF BAG

Re: does such thing as 'vintage' transistors exist?
« Reply #4 on: December 05, 2009, 04:23:22 AM »
I have occasionally had trouble getting solder to stick to old transistors.
dunno if it was the storage environment or what...
this seems to be worst with TO-92 packages.

I'd say clean the legs on the old suckers.

for some unknown reasons, and a few known ones, i don't like NTE

and good luck hunting.

j

Re: does such thing as 'vintage' transistors exist?
« Reply #5 on: December 05, 2009, 06:46:09 AM »
I know what you mean. I can only assume this is due to them being stored poorly, where the tin plating has oxidised.

Justin
Prepare yourself. You are about to become the voice of Interplanetary Parliament.

mad.ax

Re: does such thing as 'vintage' transistors exist?
« Reply #6 on: December 05, 2009, 07:56:24 AM »
Well, if it's vintage, chances are that it is oxidized!
But this is not an issue if one add some flux before soldering...

Axel

Re: does such thing as 'vintage' transistors exist?
« Reply #7 on: December 06, 2009, 12:43:05 PM »
I've bought a ton of vintage components at my local surplus store.  The owner recently showed me how to clean the oxidized leads.  Using a braided ground strap glued to a wide 'tweezer' like tool.  He said they are commercially available but easy enough to make yourself and that it works great to clean the leads without damaging vintage potted components.

Using this method I have found a far cleaner and more reliable solder joint.  When I buy parts for a project from him, I just clean all the leads while watching tv etc and they are all ready when I start building. 

My $.02 

[email protected]

Re: does such thing as 'vintage' transistors exist?
« Reply #8 on: December 07, 2009, 08:50:26 PM »
Are silicon parts really vintage?  ;D  With silicon parts there may be some differences, but they don't degrade internally like germanium parts wich may break down with time. The germanium process is fickle as most forms of germanium oxide will be slightly water soluble. Moisture and other contaminants trapped during the manufacturing process would eventually make them go noisy and reduce gain. Early germanium parts were really poor quality compared to anything today, but they sure made running the pocket radio on a 9V battery for a long time possible!

Re: does such thing as 'vintage' transistors exist?
« Reply #9 on: December 07, 2009, 10:00:57 PM »
I have found that the germanium transistors I have bought from my local surplus store are extremely reliable as far any NOS pieces that are  40-55yr old.  I recently bought a bag of 50 pinched top 2n167s and a dozen 2n169s with all but 6 not performing to spec for hFE and leakage.  Among the 62 I bought and tested almost all were within the tolerances noted on the datasheets.  Granted almost all the components I buy are mil-spec so that could make a huge difference.

Upon testing them in a basic transistor matching circuit I found 18 excellent matches in the 2n167s and 4 pairs of 2n169s within 10 pct.  I have also recently bought 30 2n652a's in original paper and plastic blister packs made in 09/64 and 7 in 10 made an acceptable pair with the rest usable in less critical parts of a pre, etc.  There may be tons of crappy germanium transistors out there, but I imagine those for sale these days are often out of spec and were discarded by the makers of the day. 

Over the last several years I have spent many hours scouring the shelves of my local 20,000sq.ft. surplus shop.  This is a place where you have to put your time in to find where the goodies are at as the owner can sell 4 fancy diodes for $10k back to the military and his time is worth more than some ancient transistors.



barclaycon

Re: does such thing as 'vintage' transistors exist?
« Reply #10 on: December 08, 2009, 06:54:51 PM »
Ha.
When I saw the title of this thread I thought you were asking about the OC71, AC128 etc.
Remember the OC71 - black-coated glass body ?
Funnily enough I had to replace some transistors in a vintage piece of gear recently.
I agree with what John said, as the recently manufactured versions were much, much better than the originals.

CJ

Re: does such thing as 'vintage' transistors exist?
« Reply #11 on: December 08, 2009, 10:54:33 PM »
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