Author Topic: Should I buy this batch of transistors?  (Read 1546 times)

neiloler

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Should I buy this batch of transistors?
« on: April 14, 2012, 01:21:33 PM »
So I've got access to a bunch of 2N1309, RCA made (some might be from TI) for about $3.50 a pop. Worth using in fuzz faces and such?
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JakeFuzz

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Re: Should I buy this batch of transistors?
« Reply #1 on: April 14, 2012, 03:14:56 PM »
The 2N1309's I have all have 200+ gains but pretty high leakage. Still useable, they are TI though not RCA. The older RCA transistors I have come across haven't been very good. $3.50 each is quite a risk to take for an untested batch though. Unless you can test either a representative sample or the entire batch I wouldn't buy them.

neiloler

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Re: Should I buy this batch of transistors?
« Reply #2 on: April 15, 2012, 12:43:03 AM »
It's through my school's shop for the electrical engineering school, so I can definitely test them out.

What's the best way to test them out, and what am I looking for? Leakage is referring to how much current is passed even when there's no base current, correct?
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JakeFuzz

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Re: Should I buy this batch of transistors?
« Reply #3 on: April 15, 2012, 01:54:34 AM »
http://www.geofex.com/article_folders/fuzzface/fffram.htm

If you go to the link above there is an outline for a very simple DC tester that will give you both gain and leakage for the transistor. This is the method most people use for testing their Ge's because it is so simple and only really requires a DMM and a few resistors. That article also states some very general guidelines for picking the transistors based on what you find. I can generally use anything with gains of 50 and above. I've used devices with up to 700uA of leakage. Right, leakage is the unwanted current flow from collector to emitter which we usually measure with no voltage across the base-emitter junction.

Let us know what you come up with! I always love coming up on untouched or unappreciated batches of transistors like this. $3.50 is definitely not surplus pricing though; you may be able to get a deal for buying bulk which would be nice.

neiloler

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Re: Should I buy this batch of transistors?
« Reply #4 on: April 15, 2012, 11:47:23 AM »
If I wanted to test NPN transistors, I'm assuming I could just put the resistors on the V+ side of things instead of the ground?

I'm not sure if they'll give any sort of bulk discount, not sure. They don't really seem to use these parts, but they also don't really give discounts. I figure for 10 of these guys I'm okay with dropping $35 on it, I could sell them later for more (ebay seems to have them going for about $15 a piece)
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JakeFuzz

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Re: Should I buy this batch of transistors?
« Reply #5 on: April 16, 2012, 09:17:24 AM »
Yeah in my testing rig I just have a switch that switches the leads to the battery when going from PNP to NPN.

neiloler

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Re: Should I buy this batch of transistors?
« Reply #6 on: April 16, 2012, 09:22:28 AM »
Nice idea. I think I'll build up a little pcb or P2P board for this. Cool. Thanks for the help!
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