Introduction to PNP transistors (20-Transistors)

How to bias a PNP transistor. How to deal with negative voltages. How to tell if it's in the forward active mode, saturation, reverse active mode, or cut-off. This is the easy way to handle PNP transistors.

Aaron Danner is a professor in the Department of Electrical and Computer Engineering at the National University of Singapore.

Video filmed and edited with help of CIT, NUS.

[danstark]

I enjoyed learning biasing calculation analysis. This is better than text book reading. You are very clear, explaining is complete. Thanks.

[SashaXXY]

I'm a hobbyist -- learned by trial and error. I've never been scared of numbers but I seldom bother to look at them when building circuits. So long as the arrows point the right way and the currents look like they're going to be well within tolerance, my stuff mostly kind of works, since I don't build anything fancy. But needless to say, I've blown up my share of components.
Anyway, I've always stayed away from PNP because I didn't know what to do with them. A few seconds into the video I had the Eurika moment. And the rest of the tutorial was cool too. Subbed. Looking forward to learning more. Thank you!

[Necrozene]

Since I was a kid, I remember that the arrow points to "N". Nice. I like to revise things, and consolidate my understanding. Thank you

[geoffrees]

Excellent tutorials Aaron. Having been in the electronics industry all my working life, I can still learn from your methods of these basic
Lessons on bipolar transistors. It will be great for the next generations coming through to follow your tutorials. Keep up the good work.

[brianhanson]

In the Navy we learned a way to easily distinguish pnp and npn transistors. Looking at the emitter, it’s either ‘pointed in from the perimeter (pnp)’ or ‘not pointed in (npn). That was 50 years ago and I still remember it.

[darrenmurphy]

thank you, for over 25 years i never understood why complementary audio output stages are considered "sub optimal" in favour of npn +npn totem pole output with phase invertion on one

[pebbleschan]

PNP I’m like dynamite, PNP I can drive a light, PNP with a power load, PNP, too much and I’ll explode!!! - from AC/DC! Rockin! 😂

[ronjones]

I just stumbled on this excellent tutorial. I am going to enjoy carching up on some reviews and new material.

[mathewmcgill]

When I was a youngster back in the 70s, all the 8 transistor radios had pnp transistors. That's my first experience with transistor, and it wasn't so hard then. Now convention has changed where you draw these things upside down.

[hooberdoober]

Very good. I wish we had vids in the '70s (in the USN) & early '80s -- when I was in EE school. Good luck.

[michaelhawthorne]

Nice video...thanks for the and Liked...

As someone who has worked with electronics since my college days back in the early eighties. One piece of info I learned that is very useful is:
To find which leg is which on a NPN
Put the Red lead of your multimeter on a Random the Black lead on what you got....Assume OL on the Multimeter....
Place the Black lead on the remaining what you got....Assume OL on the Multimeter....
Do this again but move the Red lead to another pin.
You might get OL again but if you get ~0.6, leave the Red lead on this pin and move the Black lead to the other
If you get a slightly higher reading then you can safely say the Red lead is on the Base and the Black lead is now on the Emitter.
The remaining pin will be the Collector.
You have to be patient and take accurate readings because Base Emitter voltages change dependent on the Transistor type and can be noticeably different or slightly different.
Your reading combination will tell you if the Transistor is NPN or
With practice, this method will be helpful, it has served me for years...hope this is

[evasuser]

07:02 "...the erros point to the right direction..." I learnt someting today, ty Aaron.

[randyfromm]

Thanks for answering my long-held question about WHY, specifically, PNP transistors are not as good/reliable as NPN transistors and why we don't typically use them in high-power applications unless we absolutely need to.

[robelbelay]

Thanks for the amazing and clear content, subscription earned!

[SW-qrqe]

Thanks
An unexpected but useful lesson in my daily YouTubing

[vikenemesh]

I was very intrigued by reverse active mode operation and went on a small googling tangent. Results came up with this very specific usecase for reverse-active-mode:

Fuzz-Effects for Guitars. Running VERY HIGH gain NPN Transistor (2n5089 e.g., with a whopping 1.2k in the best case) in reverse mode severely limits their gain and reduces saturation current such that the transistor itself saturates and distorts the input signal long before clipping into the supply rails. This is said to give a more "tube-like" distortion with less unpleasant harmonics.

[icebluscorpion]

I would love to see then a pure/only NPN transistor H-Bridge. Is it really that simple to just trun the NPN transistor around to get the negative side working?

[mnoxman]

If you look at textbooks and schematics from the late 50s to the late 60s you will see a lot more PNP transistors. The behaviour of PNP is more similar to the triode so they were more comfortable with it. That may be why it "blows" away people today. "kids these days" are not used to thinking of negative rail as anything but ground; I have seen some struggle with differential supplies (e.g. +15 and -15).

[kurusb]

You could have explained all the cases by superimposing the vcc= rc x ic + vce curve on the transistors operating curve of the manufacturer instead of drawing on for 20 minutes and no doubts cleared

[gjvdspam]

Thank you. Never knew about the reverse active mode.