2n3904 question

[buildafriend]

Hey dudes and possible dudettes,

Whats up with all these different 2n3904 versions? They range from 2 cents ( if you buy in bulk ) to $1.12. What one is right for me? and why? From now on I'm buying a few of every transistor I ever use so I want to cut down the possibility of ordering the wrong part.

http://www.mouser.com/Fairchild-Semiconductor/Semiconductors/_/N-5gcbZ1z0zleb?Keyword=2n3904&FS=True

[digi2t]

I believe it's a question of packaging. I think the suffix letters indicate whether they come as units, reels, bulk, etc. If they have to break a pack, naturally, you'll pay more. Also, I noticed that one model, 2N3904CTA, has the Collector as the middle pin. I assume to allow for certain production applications. There may be other differences as well, but any straight-up 2N3904 should do the job.

Personally, I get mine off EBay. Best price w/shipping wins. Usually 50 for 3 or 4 dollars. They all get tested before they get put on a board anyway. Never had a problem.

A rose, is a rose, is a rose....

Cheers,
Dino

[buildafriend]

Thanks!

I believe it's a question of packaging. I think the suffix letters indicate whether they come as units, reels, bulk, etc. If they have to break a pack, naturally, you'll pay more. Also, I noticed that one model, 2N3904CTA, has the Collector as the middle pin. I assume to allow for certain production applications. There may be other differences as well, but any straight-up 2N3904 should do the job.

Personally, I get mine off EBay. Best price w/shipping wins. Usually 50 for 3 or 4 dollars. They all get tested before they get put on a board anyway. Never had a problem.

A rose, is a rose, is a rose....

Cheers,
Dino

[PRR]

The reference pricing is 2.4 to 2.6 cents each when you buy a thousand. The tenth-cent covers tape for automated insertion, and which tape option is most/least common.

Mouser's price per-each runs 2 cents to 15 cents plus an oddball dollar version.

The 10 or 15 cents is very reasonable for taking a few 2.5-cent/1000 parts out/off a large box or reel. 10 cents gets BU "bulk" which is loose, no tape. Tape is handy for keeping your stash together, but the glue-scum does not solder well. (In automated they cut the leads off the tape and jam the body close to the PCB; myself I often prefer longer leads.)

The real question is: why is Mouser selling one transistor cheaper than Fairchild suggests for 1000-lots? It appears that Mouser is way over-stocked on the TF and TFR. Or maybe they sell SO many that they can laugh at Fairchild's suggested pricing. Note that the 2-cent price does not fall far when you buy bucket-loads: 5% off in hundreds, 1.6c in 500s. The 10-cent part falls to a third when you buy just 250. They are pushing the big-reel version and not caring how many you buy.

When you buy just a few, there's no difference "ammo pack" (folded) or "reel" (rolled); that's about how you load your mass production machine. Well, ammo tape is bent every 20 parts, reel tape won't lay quite flat...

The "R" means the parts are taped flipped emitter/collector, which may avoid a back-flip in the machine to get it in the holes the right way; does not matter in hand assembly.

http://www.fairchildsemi.com/products/discrete/pdf/to92_tr.pdf

[Zipslack]

If you want some interesting deals, try some of the oddball suppliers like Electronics Goldmine.  Sometimes you can get a bag-full for a buck or two and their surprise boxes are chock-full of interesting and/or  useful stuff for minimal bucks - usually lots of transistors, caps, and diodes along with lots of other components and hardware.