studying transistor theory and failing miserably

[suziebb]

Hi, new on here and honestly I'm pants at advanced electronics hence my dilemma. I hardly understand transistor circuit theory but need to draw an audio amplifier circuit showing essential componants for coupling signal input and voltage signal output? I also need to figure out how to work out collector voltage. please, any help appreciated!!

 

[Hero999]

You also need to be able to do it yourself because if we did it for you we wouldn't be helping you.

 

[suziebb]

I know, I'm just struggling on my own and getting ever closer to exam. Thing is I on't need transistor theory for my job but it's part of the course so just need to get an idea of how it all works. Explaining how to work out collector voltage would help without giving me any answers!

 

[suziebb]

Please I need help and this seems to be the only place I have any chance of finding it. I've read 'principles of transistor circuits ninth edition' cover to cover but am struggling with working out collector voltage, wont somebody please explain it?

 

[Ali Az Zobui]

see this

You need to make a KVL loop from the Vcc( Start with Vcc move across Rc, and across Vc (your variable)) then you will reach the circuit ground( in the common emitter configuration) .
This is an eqation with two variables; Vc and Ic.
You get Ic after you find Ib from the KVL on the B-E loop.
substitute in the first equation to solve for the collector voltage.
Be aware of the saturation mode, then you must be given Vce,sat from the question or the data sheet. I wish i helped you.

 

[Optikon]

Please I need help and this seems to be the only place I have any chance of finding it. I've read 'principles of transistor circuits ninth edition' cover to cover but am struggling with working out collector voltage, wont somebody please explain it?

Post a circuit to talk about. You can get plenty of help here.

 

[Tomble]

I'm not sure how much would count as "doing it all for you", but it would probably be ok to point out to you that a bipolar transistor's collector acts as a current source (or a current sink if you prefer), where the current passed is basically determined by that which goes through the emitter. It's close enough that for most purposes you treat it as equal even if it's not (IE=IC+IB, but IB is tiny).

If for instance, there is a resistance from the emitter to ground, then you can work out the current from the voltage across that resistance.

I trust you know how to work out the emitter voltage (or voltage swing, even), yeah?

Naturally, Ohm's law also applies to resistances driven by current sources rather than voltage sources. A common-emitter amplifier will have a resistor (ISTR maybe seeing other things used in their place occasionally but I forget) from collector to Vcc. You've presumably noticed that, right? Hopefully you have a good sense of how a current source behaves too- if not, you need to acquaint yourself with them a bit better.

Now, just join the dots. It really isn't that hard. Even I can do it Naturally there is more in a transistor amp than just this, but that's the details you've probably missed.

Working it out for "small signals" rather than absolute quantities is mostly the same deal.

 

[stevez]

There are two books that might be of some help to you - one is the "ARRL Radio Amateur's Handbook", published every year. Paul Scherz' "Practical Electronics for Inventors" book.

 

[cyprio7]

there are two extremely good books that i recommend for you. they are, "electronic fundementals" by floyed, and "electronics" by hambley. the first is more basic so if ur having trouble i would recommend the first, the second is a bit more advanced. when i was in the first year at uni doing electronic engineering i didnt understand some of the transistor and opamp stuff so i got the book that the uni recommended, and believe me it helped a lot, explains stuff very clearly, then gives u questions to do, and it shows u the answer and HOW you should work it out to get that answer step by step, its quite good. hope it helps

 

[mvs sarma]

Principles of electronics by AP Malvino published by Prentice Hall-- is a good book of those days and i feel even NOW. i suggest Suziebb to get hold of that and have afirst reading and then follow it up with what ever you are studying-- Probably you will get thro'.