Help!!! Audio Amp

[mataous]

Can anyone help me by telling me how this circuit works please! i have a project to do by tuesday and i dont have a clue how it works!!

 

[Sceadwian]

Looks like a class AB amplifier to me. What does this circuit have to do with your project and why don't you know how it works?

 

[mataous]

because i just took it from the internet! lol! ive used it to play my mp3 player from it!

 

[Sceadwian]

Not exactly your project then is it? You just picked a circuit off the net now you wanna pick the brains of people here to fill out information and turn it in? There's quiet a few things going on in that circuit, nothing excessively complex, what exactly are you having trouble with?

 

[mataous]

good point! but we have to do it for college! mu tutor said for me to do that!

 

[flat5]

Maybe this help a little.
complimentary pair bipolar amp
example:
abfet
Your circuit has fancier feedback.

 

[mataous]

well ive been doin some research on the net and found that it might have somthing todo with push-pull amplification? maybe?

 

[microtexan]

Can anyone help me....i have a project to do

At least he didn't wait until Monday evening.

 

[flat5]

I wonder if my post was useful...

 

[audioguru]

It is a very simple audio amplifier circuit.
What information about it is needed?

 

[mataous]

how it operates.

 

[audioguru]

how it operates?

Its opamp does the signal voltage amplification and the transistors boost the current. Simple.

 

[Sceadwian]

Not that simple for me audioguru =) The feedback network looks relatively complicated, at least to me.

 

[mataous]

my work colleagues said exacally the same! the transisters are the push pull part of the circuit and the op amp amplifies the circuit! they couldnt explain the feedback tho! they also said that C3 and C4 were references for the opamp! would you agree?

 

[Chippie]

The feedback network characterises the amplifier.....No point in amplifying signals above say 22khz or below 20hz...

 

[audioguru]

Not that simple for me audioguru =) The feedback network looks relatively complicated, at least to me.

The original project describes the bass-boost control in the feedback loop:
10W Audio Amplifier with Bass-boost - RED - Page61

The original simple audio amplifier is on that website (18W Amplifier using an opamp with a higher voltage rating for a higher output power) without the bass-boost control.

 

[Nigel Goodwin]

my work colleagues said exacally the same! the transisters are the push pull part of the circuit and the op amp amplifies the circuit! they couldnt explain the feedback tho! they also said that C3 and C4 were references for the opamp! would you agree?

NO - they are power supply decouplers.

It's a really crappy old circuit though, never any good, and even less so now.

 

[Sceadwian]

C3 and C4 are powersupply decoupling capacitors. They're there to buffer the power supply a little and usually located very close to the opamp.