Improved mic amp posted on Rapidshare

[Fred Bloggs]

Late at night, by candle light, Fred Bartoli
<fred._canxxxel_this_bartoli@RemoveThatAlso_free.fr_AndThisToo> penned
this immortal opus:




This tip-toeing around the issue is getting boring fast. Everyone
giving "hints" to everyone else and expecting them to come up with a
complete analysis. I suppose it's because no one really is sure and is
afraid of making a fool of himself. That, or hopes the other will make
a mistake and get something to jump on. This is no way to have a
technical discussion. Too many divas in here.

- YD.

The only one tip-toeing is the poof Eyeore. It is obvious from
inspection of the circuit that Ie1=Ie2, forced by the differential
feedback, and Ie1+Is1=Ie2+Is2=V+/4k7, forced by the approx constant
current emitter node feeds, where Iex is emitter current of Qx and Isx
is shunt current thru 6.8K at emitter node of Qx.

 

[Eeyore]

Fred Bartoli penned

This tip-toeing around the issue is getting boring fast. Everyone
giving "hints" to everyone else and expecting them to come up with a
complete analysis. I suppose it's because no one really is sure and is
afraid of making a fool of himself. That, or hopes the other will make
a mistake and get something to jump on. This is no way to have a
technical discussion. Too many divas in here.

It's so simple I have some difficulty believing anyone needs to have it
explained to them !


Graham

 

[Eeyore]

The only one tip-toeing

Tiptoeing ?

is the poof

poof ?

Eyeore.

Not me. I responded to criticism by posting not one but two working examples.

It is obvious from inspection of the circuit that Ie1=Ie2

Ie1 ~ = Ie2 in fact.

Graham

 

[Fred Bloggs]

It's so simple I have some difficulty believing anyone needs to have it
explained to them !

The similarity of you taunting and teasing little fags is beyond the
pale. Time for you to get lost.

 

[Eeyore]

The similarity of you taunting and teasing little fags is beyond the
pale. Time for you to get lost.

So what is it you don't understand about it ?

Graham

 

[YD]

Late at night, by candle light, Eeyore

It's so simple I have some difficulty believing anyone needs to have it
explained to them !


Graham

Maybe you in fact do, but still you play coy about it.

- YD.

 

[YD]

The similarity of you taunting and teasing little fags is beyond the
pale. Time for you to get lost.

The same applies to you.

- YD.

 

[Jim Thompson]

Fred Bloggs a écrit :

in fact this circuit will work, but I'd like to hear Graham's
explanation

Details please, instead of 'did you heard of feedback'.

No doubt the donkey copied it from somewhere. It's far too clever for
HWB (he who brays ;-)

...Jim Thompson

 

[Eeyore]

Eeyore penned this immortal opus:


Maybe you in fact do, but still you play coy about it.

Ask me a question about it then ! I don't happen to have the time free to post
an in depth analysis for beginners.

Graham

 

[Jim Thompson]

No doubt the donkey copied it from somewhere. It's far too clever for
HWB (he who brays ;-)

...Jim Thompson

For those trying to figure out how this circuit works... think like an
IC designer, think symmetry ;-)

As drawn it doesn't quite make 60dB of gain.

What has my curiosity tweaked is that this form of combined
differential AND common-mode feedback, with proper resistor-ratioing,
*might* eliminate the need for C2 (470uF), though it's probably a
stretch to do that AND make 60dB differential gain.

...Jim Thompson

 

[Fred Bloggs]

Late at night, by candle light, Fred Bloggs <[email protected]> penned
this immortal opus:




The same applies to you.

- YD.

Nah- you need to work on improving your English comprehension and
learning how to read your newsreader...

 

[Fred Bartoli]

Eeyore a écrit :

Ask me a question about it then ! I don't happen to have the time free to post
an in depth analysis for beginners.

Don't need an in depth analysis. Just answer *precisely* Fred's
question. It should take no more than 2 or 3 phrases.
So, restating it: how is the PNP's operating point well defined?

 

[Fred Bartoli]

Jim Thompson a écrit :

For those trying to figure out how this circuit works... think like an
IC designer, think symmetry ;-)

As drawn it doesn't quite make 60dB of gain.

What has my curiosity tweaked is that this form of combined
differential AND common-mode feedback, with proper resistor-ratioing,
*might* eliminate the need for C2 (470uF), though it's probably a
stretch to do that AND make 60dB differential gain.

Hey, don't tell him how it works before he answers ;-)

 

[Jim Thompson]

Jim Thompson a écrit :

Hey, don't tell him how it works before he answers ;-)

Sn-o-o-o-o-ort !-)

...Jim Thompson

 

[Eeyore]

What has my curiosity tweaked is that this form of combined
differential AND common-mode feedback, with proper resistor-ratioing,
*might* eliminate the need for C2 (470uF), though it's probably a
stretch to do that AND make 60dB differential gain.

It's tempting isn't it ? A nice DC amplifier too.

You could always use matched devices.

Graham

 

[Eeyore]

Don't need an in depth analysis. Just answer *precisely* Fred's
question. It should take no more than 2 or 3 phrases.
So, restating it: how is the PNP's operating point well defined?

You mean the various voltages and currents ?

Graham

 

[Eeyore]

Hey, don't tell him how it works before he answers ;-)

IDIOT. It's bloody obvious.

Graham

 

[Eeyore]

Sn-o-o-o-o-ort !-)

...Jim Thompson

You really are a bunch of silly old women.

Graham

 

[Fred Bartoli]

Eeyore a écrit :

You mean the various voltages and currents ?

Yes. What's the mechanism that precisely bias the circuit.

Just 3 phrases!

 

[YD]

Late at night, by candle light, Eeyore

Ask me a question about it then ! I don't happen to have the time free to post
an in depth analysis for beginners.

Graham

Just come up with the friggin' gain equation and be done with it. If
you won't maybe someone else can. Maybe you're afraid of someone
correcting you.

You do happen to have time enough for posting here, and a lot of it,
how about doing something useful with it. If you already know what
you're on about the write-up shouldn't take more than five minutes of
your oh-so-precious time.

Bunch of supposedly grownups pussy-footing around making themselves
look silly.