Audio Amplifier. Which class should I use?

[goldsmith]

I think at first you should ask my question in latest post . recall : how a diode does work? suppose that you are going through the street and a young boy , ( a student ) will ask you how can i use a diode and what is the duty of a diode . what you will say ? will you say i don't know or perhaps you know some things to describe ? show me ! i have a reason to ask it .

 

[Shayaan_Mustafa]

The duty of the diode is to rectify.

- - - Updated - - -

Well I can't say here that diode here is known as a free-wheeling diode. So therefore when anyone ask me about the duty of the diode. Then I will say it recitifies the signal. Isn't it?

 

[goldsmith]

Hi shayaan
I came back again !
What do you mean by rectification process ? let me simplify your act ! each diode will conduct in one direction , just one direction ! so , it means when you have connected a 1n4007 diode , and you have both directions across the resistor , your diode doesn't work , correctly !!!!! when you have connected a 1n4148 it worked , more agreeably . it is strange , ok ?? but let me tell you the reason of this action !
Did you know that each PN junction has an internally capacitor ? if yes do you know the reason ? if no i can describe it !
Best Wishes
Goldsmith

 

[Shayaan_Mustafa]

What do you mean by rectification process ?

A diode acts as a rectifier. Isn't it?

let me simplify your act ! each diode will conduct in one direction , just one direction ! so , it means when you have connected a 1n4007 diode , and you have both directions across the resistor , your diode doesn't work , correctly

Sir, I was thinking that how can I am getting both cycles across load resistor. I was sure there is some mistake in the circuit. Because I know that a diode conducts only in one direction. So it should be off when a negative cycle appears. Am I right sir?

when you have connected a 1n4148 it worked , more agreeably . it is strange , ok ??

When I used D1n4148 then I saw some spikes. While the output of the D1n4007 was just like the input.
I am unable to understand this, why is it so?

Did you know that each PN junction has an internally capacitor ? if yes do you know the reason ? if no i can describe it !

I know its name, I think you are asking for junction capacitance. Right?
But really, I don't know how to describe it, why should we consider it, what is the response of it to the high or low frequency. I am blank from these.

 

[goldsmith]

Hi again shayaan and good night !

A diode acts as a rectifier. Isn't it?

Certainly it is correct .

Sir, I was thinking that how can I am getting both cycles across load resistor. I was sure there is some mistake in the circuit. Because I know that a diode conducts only in one direction. So it should be off when a negative cycle appears. Am I right sir?

Of course it is correct but your circuit has not any mistake !

When I used D1n4148 then I saw some spikes. While the output of the D1n4007 was just like the input.
I am unable to understand this, why is it so?

Can you reshow me the result with 1n4148 and with ability of seeing some cycles ?

I know its name, I think you are asking for junction capacitance. Right?
But really, I don't know how to describe it, why should we consider it, what is the response of it to the high or low frequency. I am blank from these.

What is your definition by a capacitor ? do you know how we can make a capacitor ? what we will need ?

 

[Shayaan_Mustafa]

Good Night sir !

Can you reshow me the result with 1n4148 and with ability of seeing some cycles ?

It is a simulation with 10us.

What is your definition by a capacitor ? do you know how we can make a capacitor ? what we will need ?

Capacitor is a charge storing device. In order to make a capacitor, we need a dielectric medium and two electrodes.

 

[goldsmith]

About overshoots and spikes that you can see : as you can see those are just overshoots and spikes . and negative cycle removed ( approximately ) . it's result is better than 1n4007 !

we need a dielectric medium and two electrodes.

In a PN junction we will have two half conductor in both sides ( P and N ) . and a region without any conduction between them that called barrier . isn't it alike with a capacitor ? a dielectric between P and N !

- - - Updated - - -

About overshoots and spikes that you can see : as you can see those are just overshoots and spikes . and negative cycle removed ( approximately ) . it's result is better than 1n4007 !

we need a dielectric medium and two electrodes.

In a PN junction we will have two half conductor in both sides ( P and N ) . and a region without any conduction between them that called barrier . isn't it alike with a capacitor ? a dielectric between P and N !

 

[Shayaan_Mustafa]

About overshoots and spikes that you can see : as you can see those are just overshoots and spikes . and negative cycle removed ( approximately ) . it's result is better than 1n4007 !

Yes, it is better than 1n4007 as it has not -ve cycle. But sir it has spikes in the -ve portion, what about these spikes?

In a PN junction we will have two half conductor in both sides ( P and N ) . and a region without any conduction between them that called barrier . isn't it alike with a capacitor ? a dielectric between P and N !

Yes sir, I can visualize it. It is like a capacitor.

 

[goldsmith]

what about these spikes?

I will tell you about this , but it is not for this time , be patience !


And about capacitors ! so , as you probably know each capacitor is short circuit instead of high frequencies ( AC waves ) ( it's XC will become low ) . so , when you have used 1n4007 because it's capacitance is high , the out put was AC ( high value of capacitance will given low value of XC at 1MHZ ) . and when you have used 1n4148 because it's capacitance is lower than 1n4007 the out put was nearby our desired thing ! you understand ?

 

[Shayaan_Mustafa]

Yes I understand this. But I have question.

high value of capacitance will given low value of XC at 1MHZ

If I decrease frequency from 1MHz for 1n4007 then will it show just positive cycle?

 

[goldsmith]

If I decrease frequency from 1MHz for 1n4007 then will it show just positive cycle?

Surely yes . why you don't test it ? test it with 500 HZ and show me the result .

 

[Shayaan_Mustafa]

Here is the result, simulated with 10us

 

[goldsmith]

Why the polarity of out put voltage is reversed ? how is the configuration of your diode ? remove those items in your simulations ! (numbers of voltage and current . ) ( in main page ) . and why 10 usec ? your period is around 2ms why 10 sec ????

 

[Shayaan_Mustafa]

and why 10 usec ? your period is around 2ms why 10 sec ????

You mean I should edit my simulation profile and change "run to time" to 2ms?

 

[goldsmith]

end time around 8 ms to see some cycles .

 

[Shayaan_Mustafa]

Yes. With 8ms I am able to see some cycles.



But how do you know that at 8ms, cycle could be seen? How would I know this?

 

[goldsmith]

As you can see the action of 1n4007 is better than past ! ( in one MHZ ) .
And about how to select maximum size of simulation ( end time ) . when your period is 4 usec , if you set your end time around 8 usec thus it will show you two cycles . if you st it for 12 usec it will show you 3 cycles . you understand ?

- - - Updated - - -

And another thing : now i should go and take a bit rest ! because today was not a good day for me and it was a bit boring , ( i just designed many PCBs in a day ! hence i'm pretty tired . so lets continue our description tomorrow . until tomorrow , good bye . and good morning ! . and see good dreams .
Goldsmith :wink:

 

[Shayaan_Mustafa]

OK sir I understood.

And yes it is better than 1MHz.

- - - Updated - - -

OK sir,

Good morning you too.

 

[goldsmith]

Hi shayaan
After three days i came back again .
I was talking about diode , so , now there is an important parameter that you should know , that called recovery reverse time or Trr . did you hear about this ? if yes can you tell me what you know about this parameter ? if no , can you search about it ? if yes , show me the what you can understand from Trr in searching .
Best Wishes
Goldsmith

 

[Shayaan_Mustafa]

Hello sir!

Welcome again and much glad to see you.

I don't know what is Trr. I never heard about this.

I searched it here, but it is still not clear to me.
**broken link removed**