Science Buddies: "Ask an Expert"

i want to know that which is the base, collector and emitter of a tip122 npn darlington transistor .i am using it to make my radon detector.i searched it on net in some pictures it was given that the 1st wire is base 2nd collector 3rd emitter , but according to the procedure given the centre one is the base and the others are collector and emitter.can you tell me which one is correct .will you please tell me today as my science fair is tommorow.

Hello and welcome to the forums:

According to this page (and several others) http://www.ecs.umass.edu/ece/m5/tutoria ... orial.html it is Base, Collector Emitter. If you used the transistor specified in the materials list https://www.sciencebuddies.org/science- ... #materials (MPSW45AG) it would be different (see the data sheet here: http://html.alldatasheet.com/html-pdf/1 ... W45AG.html.

Keith

i hane not get it now also, keith can you please write clearly that which pin i should use as base, emitter and conductor of tip122 transistor to make my radon detector so i should use base collector emitter to make my detector

i have not still got it can you clearly tell me that for making my radon detector which pin should i use as base, collector and emitter of tip122 transistor . i don t have the transistor given in the material list. i would be very thankful to you. i have seen this page http://www.wabbitwanch.net/blog/?p=431 so in my detector i should make the first wire long and use it as base and the collector to the rca phono jack connector and thre remaining to the negative of the battery, it would not affect my detector please reply fast.

Hi:

According to the web link I posted, it is:

Pin 1 = Base; Pin 2 = Collector; Pin 3 = Emitter.

HTH.
Keith