Bulk NOS Component Sources? - Page 1
Forum section: electronics / projects

author: TheAdmiralty
author_rank: Contributor
timestamp: December 06, 2016, 04:47:15 pm
content: Evening, everyone!Got a quick random question here for you guys. I've been working on laying out a discrete RTL 8-bit processor (for purely academic purposes) and have reached the point where I'm going to start assembly and hardware testing. So far she's got a register file, ALU, and most of the control unit. No memory subsystems yet, though... the cache controller should be a fun one.Anyway, I need an asinine amount of 2N2222 BJTs in the TO18 package... the reason for the metal can package isn't really valid anymore, but I've already laid out three square meters of board by hand in Altium and don't feel like redoing literally everything. 10k 1206 resistors are cheap as dirt on eBay and I'm fine with just grabbing a reel and calling it a day. Does anyone know of any good sources, other than chinese eBay sellers, for complete cases of new-old-stock transistors, 7400-series logic chips, and the likes?Much appreciated!- M

author: wraper
author_rank: Unknown
timestamp: December 06, 2016, 06:44:52 pm
content: QuoteIt's like asking for multiplying component cost several times. Actually I don't see why you could not use plastic case. It's pretty common to use triangle hole layout with TO-92 package.I have a bag of these:http://www.diodes.com/_files/datasheets/ZTX689B.pdf

author: wraper
author_rank: Unknown
timestamp: December 06, 2016, 06:48:00 pm
content: Pretty robust stuff: Operating and Storage Temperature Range -55 to +200oC

author: Zero999
author_rank: Super Contributor
timestamp: December 06, 2016, 07:23:13 pm
content: Quote from: wraper on December 06, 2016, 06:44:52 pmI like the ZTX689B. It has a high gain, low saturation voltage and relatively high current. The only downside is it's only rated to 20V.Quote from: TheAdmiralty on December 06, 2016, 04:47:15 pmI believe the metal packaged 2N2222 is still available. Farnell still sell them but they're expensive. Failing that, the TO-92 package will easily fit the TO-18 foot print, simply by bending the leads.http://uk.farnell.com/multicomp/2n2222/transistor-npn-30v-800ma-to-18/dp/9206884

author: Kleinstein
author_rank: Super Contributor
timestamp: December 06, 2016, 08:10:28 pm
content: The ZTX689 is a rather large transistor - so high capacitance and thus low speed with 10 K caps.It is something like 4 times the capacitance of the 2N3904 or 2 times the 2N2222.Sometimes one can even get the TO92 transistor with the leads already bend to the triangle form.

author: TheAdmiralty
author_rank: Contributor
timestamp: December 06, 2016, 09:44:10 pm
content: Long story short, I'd planned on TO18s because I already had a small pile of them on hand at the time, and likely will have neither a soldermask or silkscreen on the board itself (I've got an LPKF ProtoMat C30 on hand to do a lot of the prototyping), meaning there's not a chance in hell of my orienting a thousand inline TO92 packages properly.I could probably do a decent job w/ a kinked lead, but this thing is going to be a one-off and it's worth $20 of my time to just keep moving with an overspec'ed component. Yeah, yeah, I know my using these is going to make some of you guys physically ill, but bear with me.Part of the reason I asked is because I'm also looking for a good number of the old SN74C/74HC chips for a virtually identical processor only using CMOS ICs instead of discrete transistors; the purpose behind this project is demonstration of the 'analog' aspects of digital design for some VLSI curriculum, and since I'd wanted to do something like this as a personal project to kill some time, it seemed like a good time to start. If there's one thing that'll make you thankful that glue logic chips exist, it's trying to route a CMOS circuit on a 2-layer PCB by hand.

author: wraper
author_rank: Unknown
timestamp: December 07, 2016, 12:59:39 pm
content: Quote from: TheAdmiralty on December 06, 2016, 09:44:10 pmLeads are formed before sticking transistors into the holes. Therefore I don't see how the lack of silkscreen is any relevant to avoiding TO-92.

author: David Hess
author_rank: Super Contributor
timestamp: December 07, 2016, 05:03:53 pm
content: Electronics Goldminesometimes has bulk deals on NOS parts.I would keep an eye out for a kinked lead TO-92 alternative to the 2N2222 like the 2N3904, 2N4401, or PN2222.Mouser has all of thesefor about 6 cents each in quantities of 100.