Transistor problem

Thread Starter

click_here

Joined Sep 22, 2020
17
Hey all,

I joined up to get some help with a simple PNP current source I made - The collector had x10 current to the emitter, and for the life of me I couldn't figure out why.

However, I ended up finding the problem: It was the fact that I was looking at a Phillips datasheet which has the C/E the other way around (facepalm).

I figured that I had signed up already, so I decided to say hi :)
 

dl324

Joined Mar 30, 2015
11,485
I joined up to get some help with a simple PNP current source I made - The collector had x10 current to the emitter, and for the life of me I couldn't figure out why.
Please post a schematic. The collector and emitter currents can't vary by 10X because \(I_E=I_C+I_B\)
 

dl324

Joined Mar 30, 2015
11,485
You may want to read my post all the way to the end :)
I did. Reversing the emitter and collector operates the transistor in inverted mode. In that mode, there's essentially no current gain, but the formula still holds. There's no way that the collector can have more current than the emitter.
 

Thread Starter

click_here

Joined Sep 22, 2020
17
Yeah, it was not behaving at all - I have no idea why I was getting those results, that was why I was about to ask here - Right before I remembered that I had a few PNPs with different pinout mixed in.

V2 was getting about 830mV

-> Maybe something else was going on, because I can no longer reproduce the problem...

I'll play around and see if I can figure out where that extra current was coming from...
 

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dl324

Joined Mar 30, 2015
11,485
Yeah, it was not behaving at all - I have no idea why I was getting those results, that was why I was about to ask here - Right before I remembered that I had a few PNPs with different pinout mixed in.
You should remove one of the diodes and use a smaller resistor for R2. That will waste less of the 15V you have available.
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