Audio Amplifier. Which class should I use?

[Shayaan_Mustafa]

oscilloscope also tells voltage. so can we take same job with voltmeter too. So can I use voltmeter in order to measure output?

Because my PC is not branded. I brought parts separately and attach them in this way I made my PC at home. So I can't ask it to the designer company Because I don't had any designer for my PC

 

[goldsmith]

oscilloscope also tells voltage. so can we take same job with voltmeter too. So can I use voltmeter in order to measure output?

Of course not . the voltmeter didn't design for frequencies above 50 or 100 HZ . and it can't show you variable waves too . ( un sinusoidal waves ) .

 

[Shayaan_Mustafa]

Now I am confused how to do next. I think I should terminate my project until I don't have oscilloscope.

BTW: What is your max output?

 

[goldsmith]

NO no no ,
It doesn't matter , i'll tell you the standard value i should measure it again .

 

[Shayaan_Mustafa]

Really. Oh thank ***. I am hoping again. Thanks a lot. Thank you goldsmith. You are very helpful.

So what should we do now?

 

[goldsmith]

Tomorrow i'll give you the result .

 

[Shayaan_Mustafa]

OK. Thanks once more.

 

[goldsmith]

Hi shayaan
Sorry for this delay to reply .
Well , when i measured it , the out put at maximum amplitude was around 2 volts . so , can you predict the required gain ?
Best Wishes
Goldsmith

 

[Shayaan_Mustafa]

Its OK sir.

Formula for gain is:
Av=Vo/Vi

I know Vo=2V. But What is Vi? I think input is mains i.e. 220V

- - - Updated - - -

Its OK sir.

Formula for gain is:
Av=Vo/Vi

I know Vo=2V. But What is Vi? I think input is mains i.e. 220V

 

[goldsmith]

Why 2 volts as out put ? it is input of your amplifier . the out put of PC will be around 2 volts . and you need 50 watts . so , what will be the required gain , that can change 2 volts to the 50 watts ? what will be the out put amplitude of your amplifier ?

 

[Shayaan_Mustafa]

So

Power is given as
P=(Av)(Vi)

Right?

So It should be look like that

Av=P/Vi
Av=50/2
Av=25

Right?

 

[goldsmith]

Why AV*Vi ? is that definition of power ? of course not . AV*Vi=VO

 

[Shayaan_Mustafa]

Definition of power is volt into current.

P=VI

- - - Updated - - -

I need to calculate gain i.e. Av

Av=Vo/Vi

And

P=VI

I have given Po=50W and Vi=2V

- - - Updated - - -

Sir I am unable to see any relation between output power and input voltage.

Kindly help me out of this.

Thanks

- - - Updated - - -

I have these three formulas
Av=Vo/Vi

Ap=Po/Pi

Ap=Av*Ai

- - - Updated - - -

I think you are asking for voltage gain.

 

[goldsmith]

Humm , see below , please , this site told good things regarding real power :
https://www.davidbridgen.com/Amplifier power vs voltage.htm
https://www.davidbridgen.com/power.htm
So , now what do you think ?
And yes i'm talking about voltage gain !

- - - Updated - - -

Another thing ! i want that you learn that when you have 2 volts as vin what should be the value of voltage across the load ,to achieve your desired power ! don't forget that we will have a buffer ( complementary stage ) after this voltage amplifier .

 

[Shayaan_Mustafa]

So You mean I should read all this stuff and understand? Then you will move further?

 

[goldsmith]

Of course yes ! the pages that i suggested , are just two interesting and simple page .it will help you to understand ( better understanding because of good diagrams )

- - - Updated - - -

Then i'll guide you to continue , because my first aim isn't this that you just build an amplifier . i want you be able to design all kind of relevant circuits . if your basic be correct then you won't have any problem .

 

[Shayaan_Mustafa]

OK. Thanks. I am reading them, its really interesting.

- - - Updated - - -

@goldsmith

Many of theory in your given stuff I have studied before so I have understood it mostly.

At 50W power. Vopp=56V.

Is that were you asking for and you want I should understand.

 

[goldsmith]

Right to the point ! congratulations !
So , the out put voltage should be around 28 or approximately 30 volts !
so AV= vo /vin ---------> 30/2 = 15 ( but in practice you'd better to select it , around 18 ) .
Ok ?

 

[Shayaan_Mustafa]

OK Thanks.

- - - Updated - - -

OK sir. Now should we move further?

 

[goldsmith]

But don't forget that your op amp has not +-30 volts , as supply ! so i suggest you to amplify your in put around 12 volts and then add another section to amplify it nearby 30 volts , so can you find a way for 2nd section ? it is simple , think about it , but if you couldn't , of course i'll guide you more .
Best Wishes
Goldsmith