Blog Suggestion:  Transistor substutions/characteristics? - Page 1
Forum section: electronics / general

author: george graves
author_rank: Super Contributor
timestamp: July 28, 2013, 02:25:12 pm
content: I can't tell you how many times I've pulled up an old(er) diagram, and - get all giitty - "Oh, I want to experiment with this!"Only to parts search and some transistor is NLA.Or me - recently it was a pn100A. So - I can pull up the data sheet for it - but how do I go about finding a replacement? I guess the easy way is to hope to find a chart that tells me what is a replacement is ?!?!?! - I googled - and failed.Or the more educational way, of know more about it's characteristics, and finding something that meets it's specs? (honestly, some of the specs in the data sheet are lost on me).I'd be interested in how you go about "characterizing" a transistor as well. Say, if someone dropped a transistor on your desk - you had no clue what it was....and said "show me the specs of it"

author: AlfBaz
author_rank: Super Contributor
timestamp: July 28, 2013, 02:36:20 pm
content: Quote from: george graves on July 28, 2013, 02:25:12 pmRead up on gummel plots

author: fpliuzzi
author_rank: Regular Contributor
timestamp: August 03, 2013, 04:41:50 am
content: Hello, I tend to run into this problem myself because I own test equipment and audio/recording gear that goes back to the late 60's and occasionally there's a need to fix something. Also, I like to build test circuits contained in old technical articles where some of the semiconductors are long out of production.As for the general topic of finding transistor substitutes...Besides having a few vintage semiconductor cross-references and substitution guides on the bookshelf in my shop, I also have quite a few cross-references that I downloaded from the web over the years.Maybe the following article will be of some interest. It's about choosing transistor replacements for repairs (at least their ideas should get you in the ball park).www.electronics-radio.com/articles/electronic_components/transistor/choosing-replacements-transistors.php...about your pn100A general purpose transistor example:According to the following site; BC639, 2SC3665, 2SC4414, 2SD1226 should all work in place of a pn100A if you have trouble finding one.http://english.electronica-pt.com/db/cross-reference.php?ref=pn100a----------And lastly, as a repair tech (non-EE) I've found the "Handyman's Guide to UNDERSTANDING TRANSISTOR DATA SHEETS & SPECIFICATIONS" helpful myself. It covers a lot of practical info in just a few pages.www.aoc.nrao.edu/~pharden/hobby/HG_DS1.pdf----------At various times my tiny M3 Electronix Semiconductor Analyzer, low cost homebrewed high voltage non-destructive breakdown tester (1000V max, 1-100uA limit) designed by Charles Wenzel, and the newly acquired simple curve tracer all have played a role in finding replacement devices (or at least keep me entertained).Well, that's my simplistic approach to this problem anyway. It can be a challenge sometimes finding a replacement transistor (etc) that works just like the original component in a vintage piece of electronics. I would like to see how others accomplish this.Regards,Frank

author: edavid
author_rank: Super Contributor
timestamp: August 03, 2013, 04:47:44 am
content: How did you decide the PN100A wasn't available? It's a cheap, current production part.When replacing a part, your first 2 stops should be findchips.com and ebay.com:http://www.findchips.com/avail?part=pn100http://www.ebay.com/sch/i.html?_nkw=pn100a&_sop=15