NPN transistor connections which end is the collector

Thread Starter

Klubowy

Joined Apr 30, 2016
7
Hi I'm just learning the basics in electronics and I'm a bit confused. Some sources say that the transistor when facing the flat side has the E B C in that order from left to right. Others maintain that when read from left to right it's C B E. Now which end is the collector and which is the emitter. I hope I didn't make it too confusing.
 

AnalogKid

Joined Aug 1, 2013
10,987
Assuming we are talking about the TO-92 package for small signal bipolar transistors, there are 6 possible arrangements of three pin signals and somewhere there is a transistor for almost every one. There is no standard. Two of the arrangements are much more popular than others, but there is no standard. "When facing the flat side", E B C and E C B are the two most popular.

Be very careful when reading datasheets. Most datasheets indicate the pinout with the part viewed from the top, but National Semiconductor (and others) often show the pinout when viewed from the bottom.

ak
 

WBahn

Joined Mar 31, 2012
29,979
Strongly ditto AK's response.

Always refer to the data sheet for THAT part from THAT manufacturer (though most manufacturers will conform to the same pinout for the same nominal part number, this isn't guaranteed) and always look carefully at the pinout diagram to see if it is as view from the top or the bottom.
 

Thread Starter

Klubowy

Joined Apr 30, 2016
7
Assuming we are talking about the TO-92 package for small signal bipolar transistors, there are 6 possible arrangements of three pin signals and somewhere there is a transistor for almost every one. There is no standard. Two of the arrangements are much more popular than others, but there is no standard. "When facing the flat side", E B C and E C B are the two most popular.

Be very careful when reading datasheets. Most datasheets indicate the pinout with the part viewed from the top, but National Semiconductor (and others) often show the pinout when viewed from the bottom.

ak
I read somewhere this trick to memorise the pins. Its a sentence: Enjoy British Columbia E B C (when facing the flat side of the transistor)
 

jpanhalt

Joined Jan 18, 2008
11,087
I read somewhere that a handy way to memorise the order of the pins on a transistor is the sentence: Enjoy British Columbia (E B C) And thats when facing the flat side of the transistor
Does not work with all NPN's.
upload_2016-6-7_7-15-58.png

That is the BC546 and many others. Checking the datasheet is the only way.

John
 

WBahn

Joined Mar 31, 2012
29,979
I read somewhere this trick to memorise the pins. Its a sentence: Enjoy British Columbia E B C (when facing the flat side of the transistor)
That would only be useful if all transistors used the same pinout. As AK pointed out, there are six possible combinations and there are transistors out there that use each of them.
 

bertus

Joined Apr 5, 2008
22,270
Hello,

Always check the datasheet as the pinout can be different for transistors, even with the same number, but an other manufacturer.
Did you ever think about the pinout combinations?
Adding fet connections you get quite a list:

Transistor_pinout.png

Bertus
 

wayneh

Joined Sep 9, 2010
17,496
One of my pet peeves is when the datasheet does not use a "3D" view for the pinout, so that it's ambiguous whether to view from above or below, or from front or back. Even if it tells you, it's still so much easier to get the pinout right when you can see the whole part in your head.
 

jpanhalt

Joined Jan 18, 2008
11,087
I can't elevate it to a peeve. So long as the B is in the center, which is not affected by the perspective, if it doesn't work, I use the "USB-protocol." That is, remove it and turn it around.

John
 

ian field

Joined Oct 27, 2012
6,536
Hi I'm just learning the basics in electronics and I'm a bit confused. Some sources say that the transistor when facing the flat side has the E B C in that order from left to right. Others maintain that when read from left to right it's C B E. Now which end is the collector and which is the emitter. I hope I didn't make it too confusing.
Any device worth using will have easy to find data somewhere online - failing that; the base/emitter junction will behave like a Zener somewhere around 5 - 8V. If the collector/base junction does that - its either a highly esoteric RF device, or scrap.
 

hp1729

Joined Nov 23, 2015
2,304
Hi I'm just learning the basics in electronics and I'm a bit confused. Some sources say that the transistor when facing the flat side has the E B C in that order from left to right. Others maintain that when read from left to right it's C B E. Now which end is the collector and which is the emitter. I hope I didn't make it too confusing.
All the comments so far are good. You need to get a data sheet for the specific transistor you have. There a lot of places on the internet to get datasheets. My favorite is www.alldatasheet.com.
 

ian field

Joined Oct 27, 2012
6,536
All the comments so far are good. You need to get a data sheet for the specific transistor you have. There a lot of places on the internet to get datasheets. My favorite is www.alldatasheet.com.
Its possible to make a few generalisations about leadout order - most Asian transistors have the sequence; BCE, most European types are; BCE, but that can be either way round with the flat side of a TO92 facing down. American transistors can be either format, but mostly EBC.

TO220 and the several variants of TO3P are BCE, the TO126 is back to front relative to the heatsink .

RF transistors often depart from these formats - sometimes the emitter is the middle pin.
 
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