Replacement BJT for TP2222A

Thread Starter

bassplayer142

Joined Jan 2, 2007
89
Does anyone know a basic BJT that would replace a TP2222A seen in the link below? It is basically being used in an existing circuit to drive different color leds. Other Basic ones I have used didn't have the same effect. Thanks!
 

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beenthere

Joined Apr 20, 2004
15,808
Any old 2N2222 or 2N3904 should work.

The statement:
Other Basic ones I have used didn't have the same effect.
is kind of mysterious. Can you say how or why they did not work (or what they were, for that matter)?
 

Wendy

Joined Mar 24, 2008
21,840
I am a real lover of the 2N2222A and 2N2907A (I use it's cased plastic cousin, the PN2222A and PN2907A). There are literally hundreds of transistors that will replace either one. The odds are in favor it is the circuit around the transistor that makes the difference, not the transistor.
 

Audioguru

Joined Dec 20, 2007
11,251
I worked with electronics all my life and I have never seen a 2N2222.
My first job was with Philips so I used their metal cased BC107 and BC157 (and BC108/BC158 and BC109/BC159) transistors then they changed them to plastic cased BC547 and BC557 (and BC547/BC558 and BC549/BC559). I also used higher current BC327 and BC337 transistors.
Then I changed jobs and used North American 2N3904/2N3906 and higher current 2N4401/2N4403 transistors.
The European and American transistors have the pins reversed.
 

Wendy

Joined Mar 24, 2008
21,840
Then you haven't worked for many companies making US military equipment. I've worked for 2, Rockwell International and Raytheon. Both of them use the heck out of this transistor in several different forms. Why I don't know, other than it is so. The odd thing is some are used in raw chip form for microelectronics, different manufactures look entirely different, though the part number is the same.

I like it because it is cheap. In plastic form I paid 8¢ for them, SMT was 4¢.

The 2N4401 almost identical, same collector current specs (600ma), slightly higher gain. You'd have trouble telling them apart. Radio Shack packs both in their 15 transistor assortment.

Fairchild claims 1.0A for the collector current on the PN2222A, but I've seen others that use the 600ma number, same as the 2N4401

2N4401

2N2222
 
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Ghar

Joined Mar 8, 2010
655
The 2N2222 and 2N2907 are definitely very popular... they have their own Wiki pages and come by default in the most sparse SPICE libraries and certainly appear on the preferred parts lists used by MIL standards.

Then there's this quote:

Since the initial product launch, the 2N2222 has become the most widely used and universally recognized transistor of all time. Billions of units have been manufactured over the past 45 years and there is continuing high volume annual production.
http://semiconductormuseum.com/Transistors/Motorola/Haenichen/Haenichen_Index.htm
 

shteii01

Joined Feb 19, 2010
4,667
Same as Bill. In our electronics class, all transistor laboratory assignments were using 2N2222.
 

Audioguru

Joined Dec 20, 2007
11,251
You might not find two 2N2222 transistors the same. They will have different hFE and Vbe. If you replace a 2N2222 with a 2N4401 then you probably will not be able to measure a difference except for the varying hFE and Vbe.
 

Wendy

Joined Mar 24, 2008
21,840
Probably not even then, the two are very similar devices.

2N2222 and 2N2222A are very old, and made by a lot of different manufacturers. I'm betting this makes for wider specs than most.

But they are milspeced, and they are also cheap. Great combination!

I have run into counterfeits though. Bummer.
 
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