Help me identify and name stages of this audio circuit

[ilop]

help me plz

dear all,

i am a student from a college, and i am given a homework from my hardware assistant, it is an audio circuit, i am asked how that ciruit works, this ciruit has some stages , i must explain it per stage, i have tried hard but i still don't find how it work,

i just know that the first stage is a bufer isn.t it?

d'oh if i haven't find how each stage work, i will not pass his course, sob2

please help me
i have upload the schematic below

 

[nand_gates]

Re: help me plz

The first stage is not a buffer its just a pre-amplifier for balance control. Its also a hi-pass
filter.
The second stage is acting as a combination of high and low pass filter.
22pf is for compensation added for loop stability.

Hope this helps !! Or do you need mathematical analysis of this circuit??

 

[ilop]

Re: help me plz

thank you nand_gates

but i am still confused about the 3rd stage, what it is used for?and how it work

,do you know the mathematical analysis about my schematic?would you like to give it to me?

thank

 

[andy1]

Re: help me plz

There is no "third stage" in the schematic. The little circuit on the far right side, which you probably mistaken for a "third stage" is actually a circuit used to power the amplify. This is called a "rectifier" used in conjunction with other device to convert AC to DC voltage.

On the schematic though, this "rectifier" circuit does not seem to be complete.

 

[Rooftop]

Re: help me plz

I hear that when you make amplifier you need at least 3 stages of pre-amp and power amplifier(maybe this one that you called rectifier?) the first stages consist of transistor(to amplify the signal) then the second one consist of op-amp then the last one before the power is for bass and treeble.Is this right?

 

[ilop]

Re: help me plz

There is no "third stage" in the schematic. The little circuit on the far right side, which you probably mistaken for a "third stage" is actually a circuit used to power the amplify. This is called a "rectifier" used in conjunction with other device to convert AC to DC voltage.

On the schematic though, this "rectifier" circuit does not seem to be complete.

no, i mean the 3rd op-amp(the right) not the rectifier, could you please tell me how it works?

 

[markty]

help me plz

I am a little confused.

You may check the figure you attached. I did not see a third opamp.
I think the first stage(opamp) is used as a volume balance amp and the 4.7uF capacitor is used to cut off the dc level. The second stage is a filter which based on the characteristic you need.

 

[ilop]

Re: help me plz

[

oops sorry, there isn't such a 3rd op-amp,i am really sorry for all of you, i mean the 2nd op-amp, is used for what?and could you tell me detail why in bass and treble there are two 1.2Kohm-resistors and two 4.7Kohm-resistors?

i would like to count the output power, does anyone know?

 

[ilop]

Re: help me plz

thank you all,
i want to ask again about my schematic, does anyone konw the mathemtical analysis?, if i want to count the power, how?

please help me

 

[Kevin Weddle]

Re: help me plz

Here is an overview. The circuit is an amplifier with gain. The capacitors are used to actively filter the frequencies that are input. An active filter is basically an amplifier and filter in one. You must always amplify and filter or you will lose the magnitude of the frequencies you want to keep. I would hesitate to give you a decible reference but it is probably 20db per decade. You can plug in the numbers and determine the gain in decibles.

 

[ilop]

Re: help me plz

dear all,
i need help about my audio schematic above (post no 1), i draw that schematic on multisim, and then simulated it, but why it has only 0,01 in Attenuate?, i gave the voltage input about 1mV (AC), but the output is only 7 micro V, why it is decreased?? my lecturer wanted an increasing not a decreasing..

is there something worng with my schematic?, please help me, it is better if there was someone would draw the correct one

note: i use multisim 7

please help me

 

[Rooftop]

Re: help me plz

have you given the op amp the Vcc?from the power? your schematic tells us that you need about +10V and -10V for the OP-AMP if you didn't give the op-amp the dc voltage the op amp won't work

 

[ilop]

Re: help me plz

have you given the op amp the Vcc?from the power? your schematic tells us that you need about +10V and -10V for the OP-AMP if you didn't give the op-amp the dc voltage the op amp won't work

yes i have gave the op-amp the Vcc, but its output still the same as the input volage, what's wrong?

if i increase the treble pot, the Av is increased too, this is right or wrong?