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Why is it PNP instead of PPN for transistors

ratstar

Aug 20, 2018
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If you list emitter base collector in that order, its actually a PPN transistor, not a PNP transistor.
You list it emitter collector base, for PNP. and thats not how I like looking at transistors.

So this is right, right? That confused me for a while, because look at this t00t from applied science, and tell me you couldn't accidentally draw the conclusion that transistors conduct positive to positive. (But that would be a long time ago for you guys, maybe u cant remember bein' a n00b.)

 

davenn

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If you list emitter base collector in that order, its actually a PPN transistor, not a PNP transistor.

No it isnt !

you should really look on the net before making such statements !

640px-PNP_BJT_-_Structure_%26_circuit.svg.png



1.-NPN-transistor-symbols-and-structure.jpg



see where you went wrong ? ;) ;)
 

ratstar

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Nope. How can it be positive connected to the positive of the supply and POSITIVE connected to the NEGATIVE of the supply!!!
 

Nanren888

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I saw someone once wrote "you should really look on the net before making such statements !"
.
Do the homework, man. Bipolar transistor theory. Look for the part under "PNP" :)
 

davenn

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Nope. How can it be positive connected to the positive of the supply and POSITIVE connected to the NEGATIVE of the supply!!!


Just believe what I have shown you.. it's the standard diagrams taught to everyone
Electronics work very well when you follow that. if those diagrams were wrong, then electronics wouldnt work
If you personally have a problem with it, then you need to change your thinking and understanding
 

ratstar

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Looking on the net does not solve the issue, I've been doing that. By some scientific transitor internals maybe it is PNP but it looks pretty confusing on the surface if your thinking of connecting one P to positive, and one P to negative, Why call it P, when it should be labelled N, cause thats what your connecting it to.

And just so you know, I have had transistors to work before, by trialing all combinations of the 3 legs, but It just pisses me off.
 

Harald Kapp

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Why call it P, when it should be labelled N, cause thats what your connecting it to.
The label derives not from where you connect it but from the doping of the semiconductor. A P-type semiconductor has an excess of "holes" (it is so called because there is a lack of electrons which leaves holes in the crystal structure). An n-type semiconductor has an excess of electrons.
P-type semiconductors alone or n-type semiconductors alone make no transistor. The magic happens at the boundary between n-type and p-type semiconductor.
 

Tha fios agaibh

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Just think of PNP as the N junction being sandwiched in the middle.

The one that always confused me is the N channel mosfet. You hook your power source to the drain and its source lead drains to ground.
 

ratstar

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Can you reverse the polarity of the emitter and collector and it doesnt even bother it? they are both P type on a PNP, why label them any different.
 

Nanren888

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Short answer: yes, it works upside down, but not as well.
That's why they label them.

Can you reverse the polarity of the emitter and collector and it doesnt even bother it? they are both P type on a PNP, why label them any different.
It's the physics of semiconductors. Have a read on it. Grab a book, or pdf, one of those ones that starts from the physics: I little harder read, but well worth it.
.
If you find a good diagram of how they are actually arranged in terms of semiconductor material, and doping, you will see that the collector and emitter are quite different in terms of shape: designed to work best rightside up. :)

A quick google lead me to a stack exchange question, https://electronics.stackexchange.com/questions/33303/what-is-the-difference-between-emitter-and-collector-for-bjts#:~:text=The%20main%20differences%20between%20emitter,probably%20even%20less%20than%201.
which included this figure

jpTm0.gif

NPN admitedly, but similar applies.
 

Tha fios agaibh

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It can tolerate some reverse current but
The N (base) of a biased PNP transistor is more negative that the other P terminals.

That is why its labeled that way.

The letters don't mean how to hook it up + or -, it's indicating the junction inside the component.

A BJT works on current flow which is dependant on polarity. Thinking of just polarity can confuse matters.

The PNP allows current to flow from the Emitter to the collector when a small current flows out of the base when its more negative than the emitter.
 

Audioguru

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Can you reverse the polarity of the emitter and collector and it doesnt even bother it? they are both P type on a PNP, why label them any different.
Simply look at the datasheet of a transistor. For example, the 2N3906. Its maximum allowed reverse-biased emitter base is only 6V but is usually never reverse biased.

I have never tried it but when it is connected backwards, its current gain is only about 7 times instead if its normal 200 times.
 

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Bluejets

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I have never tried it but when it is connected backwards, its current gain is only about 7 times instead if its normal 200 times.

Talkingelectronics have a simple amplifier test on a transistor that shows exactly that.
 

hevans1944

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I have had transistors to work before, by trialing all combinations of the 3 legs, but It just pisses me off.
Getting "pissed off" just because you don't know WTF you are doing is not an effective way to learn almost anything. It's a good thing you didn't start trying to learn electronics with vacuum tubes containing thermionic emitters, one or more plates (anodes), and several wire grids or beam-forming electrodes between the emitter(s) and the anode(s). Testing all combinations of voltage and polarity applied to pairs of electrodes on a vacuum tube can take awhile, with no guarantee that any combination you try will produce a useful circuit.

And God forbid if you ever get introduced to the Burroughs beam-switching decade counter tube, used for what was then high-speed pulse counting in the 1960s and capable of directly driving Nixie display tubes. This one rates right up there with the venerable phantastron circuit in terms of trying to understand how either one actually works. But it's worth the effort. A little physics, a lot a math, some grounding in theory and you could be an expert in practically no time. Of course you would then need re-training to grok semiconductors, but vacuum tube circuits may be making a comeback because they are virtually immune to radiation damage, which is useful for, say, an Earth to Mars mission. This would be a good time to pick a path to success, maybe even garner a mission-seat on the first human-manned (as opposed to robots) mission to Mars. What a thrill that would be! And you could tell all those semiconductor weenies to go pound sand, which is what semiconductors are usually made from... silicon semiconductors anyway.

I can remember as a teenager in the 1960s spending some time at the base electronics hobby shop in Smyrna, Tennessee. This was
Dad's last "permanent duty station" before he retired. The electronics hobby shop occupied one half an isolated wood-framed building and the other half was set up as a class room for airmen trying to improve their education. I knew zip about transistors, but there were some becoming available to hobbyists at that time, so the airman (a staff sergeant IIRC) who ran the hobby shop and I developed a "bread board" system for building and testing circuits.

This DIY bread-board involved drilling opposing holes through two non-conducting panels in a grid-like layout... perhaps as many as a hundred holes in a 10x10 array paced about an inch apart, although I recall making a smaller version for myself, about 25 holes on a 5x5 grid. One set of holes was much larger than the other, allowing room to stick a finger tip through those holes. We gathered up a hundred or so steel paper clips, unfolded them, and then bent them back into a long, slender, oval and soldered the ends together. Next the two panels were assembled with spacers so the modified paper clips would just peek through the small holes on the top panel when the other end of the paper clip was flush with the hole opposite.

Finally, high-test nylon fishing line was threaded through all the paper clips at the larger holes in a criss-cross fashion. The fishing line was pulled as tight as we could and it served as a "spring" to draw down the paper clip protruding from the top panel until it was flush with the top panel. Now for the "fun" part. We pushed up from the bottom with a finger to create a little loop of paper clip wire protruding from the top of the panel. Into this loop we could insert two or more wires. Voila! a prototyping bread-board of sorts. Not good for very complicated circuits, and the contact with the wires stuck through the paper clips was somewhat iffy, but we made do. We built oscillators and audio amplifiers mostly, and tried to learn transistor theory from the text books stored in the next room. Neither I nor my airman mentor understood much about how transistors worked.

So we experimented. IIRC we did try reversing the emitter and collector connections, operating the transistor :"upside down" so to speak. This actually sort of worked, but with virtually no gain compared to the normal "right side up" configuration. So we abandoned that idea and were careful to identify the emitter, base, and collector terminals of each transistor. It was about ten years later, after a four-year tour of duty in the Air Force, and later study at the University of Dayton in pursuit of a degree in electrical engineering, that I finally began to appreciate the physics of transistors. This turned out to be essential to understanding why I couldn't "make" a transistor by soldering together two siilicon diodes.

Ah, well. Learning electronics is a journey, not a destination. But it is easy to get side-tracked because of some lack of understanding regarding some vitally important concepts. Good luck on your journey @ratstar. It does not require any understanding of Maxwell's Equations to operate a radio, but such understanding goes a long way toward designing and building a radio system.
 

ratstar

Aug 20, 2018
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With only 3 legs on a transistor its only ABC,ACB,BAC,CBA,BCA,CAB - 6 permutations, but then you need to test all the polarities, and its fiddly as hell with all the wires going everywhere.

I tried the two diodes making a transistor as well, because I saw a gif of it on the internet, and it didn't work for me either. The PNP configuration doesn't make a transistor by itself, I looked at it quite a while, theres something else going on in one that makes it work.

I still haven't given up on making an *active* gate (you can make a passive gate with just a voltage divider) from diodes, caps and resistors + some kind of power supply setup, because I haven't fully nailed in the coffin yet, and theres more to garner from the situation still for me, even if it ends up impossible.

That DIY bread board sounds really cool! =)
 
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WHONOES

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Getting "pissed off" just because you don't know WTF you are doing is not an effective way to learn almost anything. It's a good thing you didn't start trying to learn electronics with vacuum tubes containing thermionic emitters, one or more plates (anodes), and several wire grids or beam-forming electrodes between the emitter(s) and the anode(s). Testing all combinations of voltage and polarity applied to pairs of electrodes on a vacuum tube can take awhile, with no guarantee that any combination you try will produce a useful circuit.

And God forbid if you ever get introduced to the Burroughs beam-switching decade counter tube, used for what was then high-speed pulse counting in the 1960s and capable of directly driving Nixie display tubes. This one rates right up there with the venerable phantastron circuit in terms of trying to understand how either one actually works. But it's worth the effort. A little physics, a lot a math, some grounding in theory and you could be an expert in practically no time. Of course you would then need re-training to grok semiconductors, but vacuum tube circuits may be making a comeback because they are virtually immune to radiation damage, which is useful for, say, an Earth to Mars mission. This would be a good time to pick a path to success, maybe even garner a mission-seat on the first human-manned (as opposed to robots) mission to Mars. What a thrill that would be! And you could tell all those semiconductor weenies to go pound sand, which is what semiconductors are usually made from... silicon semiconductors anyway.

I can remember as a teenager in the 1960s spending some time at the base electronics hobby shop in Smyrna, Tennessee. This was
Dad's last "permanent duty station" before he retired. The electronics hobby shop occupied one half an isolated wood-framed building and the other half was set up as a class room for airmen trying to improve their education. I knew zip about transistors, but there were some becoming available to hobbyists at that time, so the airman (a staff sergeant IIRC) who ran the hobby shop and I developed a "bread board" system for building and testing circuits.

This DIY bread-board involved drilling opposing holes through two non-conducting panels in a grid-like layout... perhaps as many as a hundred holes in a 10x10 array paced about an inch apart, although I recall making a smaller version for myself, about 25 holes on a 5x5 grid. One set of holes was much larger than the other, allowing room to stick a finger tip through those holes. We gathered up a hundred or so steel paper clips, unfolded them, and then bent them back into a long, slender, oval and soldered the ends together. Next the two panels were assembled with spacers so the modified paper clips would just peek through the small holes on the top panel when the other end of the paper clip was flush with the hole opposite.

Finally, high-test nylon fishing line was threaded through all the paper clips at the larger holes in a criss-cross fashion. The fishing line was pulled as tight as we could and it served as a "spring" to draw down the paper clip protruding from the top panel until it was flush with the top panel. Now for the "fun" part. We pushed up from the bottom with a finger to create a little loop of paper clip wire protruding from the top of the panel. Into this loop we could insert two or more wires. Voila! a prototyping bread-board of sorts. Not good for very complicated circuits, and the contact with the wires stuck through the paper clips was somewhat iffy, but we made do. We built oscillators and audio amplifiers mostly, and tried to learn transistor theory from the text books stored in the next room. Neither I nor my airman mentor understood much about how transistors worked.

So we experimented. IIRC we did try reversing the emitter and collector connections, operating the transistor :"upside down" so to speak. This actually sort of worked, but with virtually no gain compared to the normal "right side up" configuration. So we abandoned that idea and were careful to identify the emitter, base, and collector terminals of each transistor. It was about ten years later, after a four-year tour of duty in the Air Force, and later study at the University of Dayton in pursuit of a degree in electrical engineering, that I finally began to appreciate the physics of transistors. This turned out to be essential to understanding why I couldn't "make" a transistor by soldering together two siilicon diodes.

Ah, well. Learning electronics is a journey, not a destination. But it is easy to get side-tracked because of some lack of understanding regarding some vitally important concepts. Good luck on your journey @ratstar. It does not require any understanding of Maxwell's Equations to operate a radio, but such understanding goes a long way toward designing and building a radio system.
Ah, James Clerk Maxwell a Scotsman. One of the cleverest people the most people have never heard of. Even Einstein was in awe of him. He calculated the speed of light; Predicted the presence of radio waves which arose from his work on electricity. He also did a lot of work on colours and how any colour could be made from just the 3 primaries. He also designed, built and ran the Cavendish laboratories at Cambridge University.
 

Audioguru

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With only 3 legs on a transistor its only ABC,ACB,BAC,CBA,BCA,CAB - 6 permutations, but then you need to test all the polarities, and its fiddly as hell with all the wires going everywhere.
If you buy transistors from a real local electronic parts distributor and not fake ones from ebay then the distributor or Google has the manufacurer's datasheet that shows which pin is which. That is why I buy parts from Digikey and look on Google.

I design and plan a parts layout for a circuit then build it soldered together on a stripboard with the strips cut so that the circuit is compact and there are no intermittent "fiddly" wires all over the place.
 

ratstar

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Doesnt take many wires for it to get fiddly, programming only requires keyboard and mouse, electronics with the hands is very frustrating for everyone i'm pretty sure.

fiddly.png
 
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