# transistors



## eng.dork (Sep 11, 2007)

In the NCEES sample questions book all they show is BJT transistors in the morning exam. Do we need to also be prepared for FET's?


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## Flyer_PE (Sep 11, 2007)

I don't think there was a FET question on the morning portion when I took the exam. YMMV.

Jim


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## benbo (Sep 11, 2007)

THe NCEES specifications say "Transistors" so I assume that could mean anything.

What I am saying here is just my opinion -

I wouldn't worry about it too much, but you never know. I certainly wouldn't study up on FET amplifiers, and unless I was taking the ECC afternoon, I wouldn't memorize a lot or work a lot of problems on FETs.

But, if it was me, I would just try to learn how to find some basics in a reference like the EERM.

I would only worry obout JFET and MOSFET.

I would have a reference to show me whether a certain drawing was depletion or enhancment, n channel or p channel.

Then I would just have a reference for the basic formulas, like be able to plug into a formula given a Vp and Vgs and find Id.


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## Dark Knight (Sep 11, 2007)

If you are taking Power Module don't worry about it. Just be sure you have a decent electronics book. I can e-mail you some material I have that worked for me like a charm. PM me your e-mail and I will forward the notes to you.

Again, it was only good for one problem, maybe two, but one question might be the difference. You have to decide if it worths the trouble.

As my friend Benbo said, it was like plug and play. It happened that I reviewed that material three days before the test. When I saw the problem I knew where to look for help.

Better lucky than good!!!!!!!!!!!

:bio:


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## jdd18vm (Sep 11, 2007)

Good question. I have been struggling in general how much to focus on ALL these electronics, instrumentation and controls...LOL (im screwed)

I like you're idea Jim of getting proficient at the morning stuff. I am just not having the same luck. I think I will feel better with the Power Afternoon, but KNOW you have to pick up morning points. So I guess that bodes the question that leads to the long debate of passing score. How many point can afford to miss in each section. Note how I didn't ask what it takes to pass...

Somewhat rhetorical but appreciate the feedback as always.

John


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## mudpuppy (Sep 11, 2007)

BringItOn said:


> Better lucky than good!!!!!!!!!!!


A motto to live by!

I wouldn't be too surprised to see a MOSFET on the morning session, but a regular FET seems a bit esoteric for the (morning) exam. I think the 6 minutes solutions had some MOSFET questions.

I'm terrible at electronics, but I actually seem to understand MOSFETs. It helps that the gate current is zero.


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## jdd18vm (Sep 11, 2007)

mudpuppy said:


> A motto to live by!
> I wouldn't be too surprised to see a MOSFET on the morning session, but a regular FET seems a bit esoteric for the (morning) exam. I think the 6 minutes solutions had some MOSFET questions.
> 
> I'm terrible at electronics, but I actually seem to understand MOSFETs. It helps that the gate current is zero.



its a damn good motto....with Tminus 45 Days....it may be my best hope!!


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## adc_PhDPE (Oct 18, 2007)

eng.dork said:


> In the NCEES sample questions book all they show is BJT transistors in the morning exam. Do we need to also be prepared for FET's?


There is a possibility that FETs are on the exam especially if you decide to take Electronics, Controls and Communications in the afternoon. In the morning section, they could ask you to find the DC drain current (Id) which should be within the six minute time frame. The key is once you have the BJTs down then the analysis and design of FETs should be easier (espically with the DC case). Hope that this helps. Good luck!


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## Ilan (Oct 19, 2007)

Does anyone have these notes. Electronics is one of those topics I am worried about. Please PM me if you have these notes.

Thanks,

Ilan.



BringItOn said:


> If you are taking Power Module don't worry about it. Just be sure you have a decent electronics book. I can e-mail you some material I have that worked for me like a charm. PM me your e-mail and I will forward the notes to you.


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## chicago (Oct 19, 2007)

So, I take it that studying the AC equivalent h-parameter models (for low frequencies) and hybrid-pi models (for high frequencies) can likely be placed out of the scope for the morning?

I sure hope they only ask the DC values.

Even looking at the AC 1st order low freq model for transistors gives me the heeby jeebies, let alone a panic attack!


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## Flyer_PE (Oct 19, 2007)

chicago said:


> So, I take it that studying the AC equivalent h-parameter models (for low frequencies) and hybrid-pi models (for high frequencies) can likely be placed out of the scope for the morning?


Based on my experience and what I have heard from others, that stuff can be placed well out of scope for the breadth portion of the exam. I wouldn't spend any time worrying about them.

Jim


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## benbo (Oct 19, 2007)

chicago, Ilan - I think you guys are going to breeze the AM. Don't sweat the details on the small signal models - I couldn't even solve this stuff in school and I passed the test. You do want to know a little about the biasing. The test really is evauating your practical knowlege and your knowlege of concepts. They may want you to know WHAT an h parameter model is, but not how to use it. A good example is that transistor problem in the NCEES exam which has an AC input and ask about clipping. When they give you the Hfe (or beta) you don't really have to use it for anything (unless you want to plug it in and calculate the alpha). You just have to realize that for a transistor with a big Hfe, then Ic basically equals Ie. And you can almost always make that assumption anyway.

Most engineers would do this type of design on a computer.


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## Dark Knight (Oct 19, 2007)

Ilan said:


> Does anyone have these notes. Electronics is one of those topics I am worried about. Please PM me if you have these notes.
> Thanks,
> 
> Ilan.


Maybe a month ago I e-mailed these notes to somebody here, maybe to more than one person. Don't have the notes with me since I am out of town. If you read this post and you are one of the persons I did e-mail the notes please PM Ilan.

Thanks


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## adc_PhDPE (Oct 20, 2007)

chicago said:


> So, I take it that studying the AC equivalent h-parameter models (for low frequencies) and hybrid-pi models (for high frequencies) can likely be placed out of the scope for the morning?
> I sure hope they only ask the DC values.
> 
> Even looking at the AC 1st order low freq model for transistors gives me the heeby jeebies, let alone a panic attack!


Chicago, I agree with BringIt. Unless you are planning to take the Electronics, Controls, and Communications then I wouldn't worry much (in my opinion) about studying in depth transistors for the PE exam. Honestly, the h-parameter models are useless anyway unless you know the models and relationships inside out. The h-parameter models will basically give you the same information as if you did the "normal analysis" of the information as well (actually would be much quicker).

As a last minute resort I would review over the DC analysis as well as the load line equations for the BJT and FET models. Once you understand those then you should be good for the breadth portion of the exam. I would also review over the graphical analysis when produced an AC signal (reviewing effects such as clipping and clamping). Those are good candidates for the PE exam as well. Hope that this helps and Happy studying :bananalama:

P.S&gt; Did you go to school in Chicago?


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## chicago (Oct 20, 2007)

adc_PhDPE,

Thanks for the advice. I went over the DC analysis like you mentioned and I think I have it down pat. I just don't see them asking a whole lot about load lines in the current exam format, except for if it's graphical and they ask you about a region of operation. But, I think Q-points are fair game.

What I'm dreading are the pulse circuits like waveform shaping and logic. I can follow the variations of the diode configurations up to a certain extent like the 2 questions on the NCEES morning sample exam. Anything beyond that, I will opt for an educated guess!

Yes, I went to UIC and IIT universities in Chicago.


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## adc_PhDPE (Oct 20, 2007)

chicago said:


> adc_PhDPE,
> Thanks for the advice. I went over the DC analysis like you mentioned and I think I have it down pat. I just don't see them asking a whole lot about load lines in the current exam format, except for if it's graphical and they ask you about a region of operation. But, I think Q-points are fair game.
> 
> What I'm dreading are the pulse circuits like waveform shaping and logic. I can follow the variations of the diode configurations up to a certain extent like the 2 questions on the NCEES morning sample exam. Anything beyond that, I will opt for an educated guess!
> ...


Chicago,

That's what I was talking about. when you go through the DC analysis of transistors to include the load lines then you will understand the Q-points. The large signal analysis is about how the large AC signals are when it comes to clipping and clamping (those are fair game especially on the morning portion of the exam since with some tricks it can save soem time for the exam) . Knowing (or having in your bank) the rectifiers (half and full wave) are good to have and know. But for the most part for diodes is that you should know when (or how) the diode conducts and when it doesn't (which you would need to keep track of the current flow). Hope that this helps.

P.S&gt; Really? I went to IIT. I went there in the early to mid 90s and I finished my PhD from RPI. To give you some consulation I know of three of our alums (including myself) that have their PEs (Civil, Materials, and Electrical) so I know that you can do it.


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## mudpuppy (Oct 21, 2007)

adc_PhDPE said:


> P.S&gt; Really? I went to IIT. I went there in the early to mid 90s and I finished my PhD from RPI. To give you some consulation I know of three of our alums (including myself) that have their PEs (Civil, Materials, and Electrical) so I know that you can do it.


IIT was on my short-list of schools; I really liked it and wanted to go there, but in the end my money situation just didn't allow it.


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