Our EDIT# mid-term project

[Juglenaut]

We have to design and build a cascading 3 stage transistor amp, quite simple, but we were told we have to find the formula to find how to build this circuit for a total gain of 100.

first stage gain of 8, second gain of 12, with a total gain of 100, and VCC of 12 volts.

I know quite simple, but yeah I need some input.

 

[Roff]

Is this an audio amp? Does it have to drive anything? Are there any requirements for input impedance, output impedance, power out, bandwidth, etc.?
With 2 stages, you already have a gain of (8*12)=96. Is the 3rd stage supposed to have a gain of 1.04?

 

[JimB]

A few things are irritating me here.

You have declared that this is a "lame mid-term project", you have stated that it is "quite simple" - twice.

You have asked for input (help), without stating the full specification of the amplifier.

If the lame project is quite simple, what efforts have YOU made to work out how to do this project, apart from asking this forum?

Come to think of it, what sort of a project would you not class as "lame"? Or, is it just lame because you have no idea where to start and you have to do a bit of maths to get the design right before building it?

Now here is the helpfull bit, try the book "The Art of Electronics" by Horowitz and Hill, ISBN 0-521-37095-7, your college library should have it.
I have the second edition and chapter 2 around page 84 may be a good starting point for you.

JimB

 

[stevez]

I wish that I had the good sense to make as much as I do now, of opportunities to learn from more basic situations. While the simple things can seem quite lame they are often arranged so that you make some mistakes - but also that you learn from the mistakes and succeed in the end. Unfortunately the more exciting projects are often more complex - to the degree that you'd get so bogged down you'd get frustrated and quit. I'm inclined to side with JimB except that I'd add that there is no shame in starting at the beginning - everyone starts there. There's nothing wrong with admitting that your project is relatively simple though it helps to demonstrate that you've put forth some effort to help yourself. One has to crawl before they walk, walk before they run. Crawling and walking might not be fun but that's how you get to run.

 

[Juglenaut]

Well I see that most people don't have a sence of humor, I am being lectured about life by people that don't even know me, sweet...

In the time it took you to write a biased reply I found the required formula in a book that the Instructor let us read though.

To be to spec the amp is a 3 stage voltage divided base biased transistor class A amp.

The reason is why I said this Lame so to speak as we were told to used these specified gains, and from a design stand point the variety would be small. Of course you could incline to use several transistors or even a darlington pair making it somewhat more of a challenge, I was simply illustrating in a humorous way. Notice I only out Lame in the topic not in the body of the post, like as in 'Lame simple' I will simply state that for a mid-term, I think for a mid-term project we should throw in more varibles and make it more of a self-design type thing, mabey do alittle soldering. In the 2 years here we haven't even did any soldering projects, personally I started to solder at age 8 building batteries.

I am really not the one to care about internet humor confusion, it is your own fault that such things irritate you.

Come to think of it, what sort of a project would you not class as "lame"? Or, is it just lame because you have no idea where to start and you have to do a bit of maths to get the design right before building it?

Math is the easy part so is building for me, from where do You -> think that I don't know where to start. Do you honestly think you can tell me what you think I am. Just because I am a Newbie to text and learning the basics of design doesn't mean I had no idea before I started School. Everyone is different, yes I know this, it is common sence that everyone has different abilities, attributes, knowlege, etc...I am not one to jump to conclusions.

I only asked for a Av formula or gain formula well mabry didn't imply to ask for it directly, not for the forum to design it for me. I knew it had to be close to Unity gain on the third stage, I even built some common collector stages to relect this type of gain.

At least Ron H, had common place and asked me questions and gave me a few pointers, which I thank you not just for the help but also by not jumping to conclusions..

 

[JohnBrown]

Ouch!

 

[JimB]

Wow, I really hit a raw nerve there!
Maybe I was a little too near to the truth.

However, it looks like you managed to answer your own question without ANY help from the forum, that is good, well done.

Whilst I came down hard on you for what appears to be a lazy attitude, please re-read my first post and note that I did give you a reference to where you may find some relevant information which will help you. Maybe this was the same book that the instructor let you read.

JimB

 

[Juglenaut]

Whatever

Now I am lazy. :roll:

It all boils down to if you have nothing better to say than to discriminate or have presumtions, then don't bother.

 

[Nigel Goodwin]

Whatever

Now I am lazy. :roll:

It all boils down to if you have nothing better to say than to discriminate or have presumtions, then don't bother.

These forums don't exist to do students work for them!, it helps no one (particularly the student!), and you didn't even bother posting enough details for the question to make any sense - which is why you didn't get any detailed answers - mainly requests for more information.