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[DPRG] emitter/collector/base

Subject: [DPRG] emitter/collector/base
From: Sluggy! slugmusk at linuxlegend.com
Date: Tue Jul 24 23:21:36 CDT 2001

montgomery f. tidwell wrote:

> can someone explain (in newbie terms) what these three mean?
> (in relationship to an a1015/nte290a/power regulator??)
> 
> i assume that one is to ground, one is input, and the other is
> output. but which is which?

I think you may have some pin label confusion there.

With a three terminal regulator, there will indeed be an input, output 
and ground pin. Usually, with the part number up and the pins pointed at 
you, the are, left to right, input, ground, output. The heatsink tab is 
usually also ground.

Where the confusion may come from is that the same sort of three pin 
TO-220 case that you regulator is in is also used for many transistors, 
which have emitter, collector and base pins, not necessarily in that 
order. You may also find FETs in this package, the pins being labeled 
base, drain and source. Who knows, there may be 50 other things 
available in the same package. And the package isn't limited to 3 pins, 
I've seen 5 pin audio amplifiers in the same package.

So, to summarize:

1. A regulator and a transistor of any design are not interchangable. 
Make sure you know which you have.

2. Emitter, base and collector pins are variable, although the heat sink 
and center pin are _usually_ the collector or the drain, there is no 
guarantee of that.

3. Never use a 9 iron to kill an emu, even for charity.

Sluggy!


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