audio amplifiers: +/- X VDC vs 0-X VDC

[Al in Dallas]

On Sat, 29 Sep 2007 00:23:33 GMT, Rich Grise <rich@example.net> wrote:

On Fri, 28 Sep 2007 15:20:58 -0700, zhafran wrote:
On Sep 29, 12:03 am, Rich Grise <r...@example.net> wrote:
On Fri, 28 Sep 2007 05:41:54 +0000, Michael Black wrote:
Rich Grise (r...@example.net) writes:
On Wed, 26 Sep 2007 02:11:12 +0000, Michael Black wrote:

As someone pointed out, another method of getting rid of the DC
component is to feed the other side of the speaker with an out of
phase audio signal:

Audio ---------------AMP1 --
| speaker
|--inverter----AMP2---

Geez! Inverted is not equal to "out of phase". They're precisely in
phase, simply of opposite polarities.

Please don't confuse the newbies.

So which part are you taking issue with?

Using the term "out of phase" when there is no phase difference.

Imagine a pulse train:

_ _ _
__________| |__________| |__________| |_____

THIS is 180 degrees out of phase:
_ _ _
___| |__________| |__________| |_____

THIS is merely inverted:
__________ __________ __________ ______
|_| |_| |_|

Get it now?

I'm just confuse about some basics here. can the 2 sinusoidal waves that
is 180 degrees out of phase with each other be said as inverted? and, for
waveforms other than sinusoidal shape is not necessarily inverted when
they are 180 degrees out of phase?

To invert a signal, you run it through an inverter, To phase shift it, you
run it through some sort of phase shift network; this will be frequency-
sensitive, depending on the frequency and the parameters of your phase
shifter.

And anyone who tells you that an inversion is the same as a 180 degree
phase shift just wasn't paying attention in class that day.

Admittedly, with a sine wave, they LOOK exactly the same; this is
probably the confusion factor for those who don't know the difference
yet.

I think you've hit the nail on the head.

--
Al in St. Lou

 

[Al in Dallas]

On Fri, 28 Sep 2007 22:00:12 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

Eeyore wrote:


Jamie wrote:


In the case of Audio circuits using a dual rail +/- with
respect to common. These circuits do not apply their +/-
rails simultaneously through it's output as it's being driven. If they
did, that would obviously cancel each other out with the exception of
low current needed to bring the complemary pairs out of cut off. Real
basic circuits often use a couple of diodes in series to list the bias
between the NPN/PNP's base circuits.


What a load of drivel.

Don't you ever feel embarassed writing such junk ?

Graham

You're such a smuck.

???

You must of been a real prize in your day.

He's not dead, putz.

--
Al in St. Lou

 

[Eeyore]

Jamie wrote:

Eeyore wrote:
Jamie wrote:

In the case of Audio circuits using a dual rail +/- with
respect to common. These circuits do not apply their +/-
rails simultaneously through it's output as it's being driven. If they
did, that would obviously cancel each other out with the exception of
low current needed to bring the complemary pairs out of cut off. Real
basic circuits often use a couple of diodes in series to list the bias
between the NPN/PNP's base circuits.


What a load of drivel.

Don't you ever feel embarassed writing such junk ?


You're such a smuck.

You must of been a real prize in your day.

You mean "have been".

You can't even write using the English language competently.

Graham

 

[Eeyore]

"Michael A. Terrell" wrote:

Eeyore wrote:
Jamie wrote:

In the case of Audio circuits using a dual rail +/- with
respect to common. These circuits do not apply their +/-
rails simultaneously through it's output as it's being driven. If they
did, that would obviously cancel each other out with the exception of
low current needed to bring the complemary pairs out of cut off. Real
basic circuits often use a couple of diodes in series to list the bias
between the NPN/PNP's base circuits.

What a load of drivel.

Don't you ever feel embarassed writing such junk ?

Graham

Do you?

I'd certainly feel embarrased if I'd been responsible for writing such idiotic
gobbledegook.

Graham

 

[Michael A. Terrell]

Eeyore wrote:

"Michael A. Terrell" wrote:

Eeyore wrote:
Jamie wrote:

In the case of Audio circuits using a dual rail +/- with
respect to common. These circuits do not apply their +/-
rails simultaneously through it's output as it's being driven. If they
did, that would obviously cancel each other out with the exception of
low current needed to bring the complemary pairs out of cut off. Real
basic circuits often use a couple of diodes in series to list the bias
between the NPN/PNP's base circuits.

What a load of drivel.

Don't you ever feel embarassed writing such junk ?

Graham

Do you?

I'd certainly feel embarrased if I'd been responsible for writing such idiotic
gobbledegook.

So, you never read what you post?

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Nobody]

On Fri, 28 Sep 2007 15:20:58 -0700, zhafran wrote:

I'm just confuse about some basics here. can the 2 sinusoidal waves
that is 180 degrees out of phase with each other be said as inverted?

Yes, as sin(x+180°) = -sin(x)

and, for waveforms other than sinusoidal shape is not necessarily
inverted when they are 180 degrees out of phase?

Correct.

More genrally, for waveforms which contain only odd harmonics (e.g. sine,
square, triangle), inversion is the same as a 180-degree phase shift. If
there are any even harmonics (e.g. a sawtooth wave, or anything with a DC
component), then they aren't the same.

 

[John Fields]

On Tue, 25 Sep 2007 20:48:50 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

Eeyore wrote:


Jamie wrote:


If you were not using a dual polarized rail supply, then you would
have problems because the design would force you bias the IC so that the
output is generating 50% of the supply voltage. In this case, you'd need
a decoupling cap.


No, you'd need a COUPLING capacitor.

Graham

Ignorant sap sucker.

Go back and count your marbles, I think you've
lost some.

---
Once in a while Graham is right, and this is one of those rare
occasions.

A "coupling" capacitor is used to connect (couple) the output of one
stage with a quiescent DC different from that of the input of the
next stage by using the dielectric of the capacitor to allow both
stages to float into AC commonality with each other while
disregarding their DC differences.


--
JF

 

[John Fields]

On Wed, 26 Sep 2007 19:50:20 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

Don Bowey wrote:

On 9/25/07 5:48 PM, in article BMhKi.70$n96.62@newsfe06.lga, "Jamie"
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:


Eeyore wrote:


Jamie wrote:



If you were not using a dual polarized rail supply, then you would
have problems because the design would force you bias the IC so that the
output is generating 50% of the supply voltage. In this case, you'd need
a decoupling cap.


No, you'd need a COUPLING capacitor.

Graham


Ignorant sap sucker.

Go back and count your marbles, I think you've
lost some.



There is nothing wrong with using a wrong term, but why show your ignorance
over it by arguing when someone corrects the term? It is, after all, a
coupling capacitor.

Yes, that is true, It's also termed Decoupling capacitor because of
the interaction of what it's used in.

---
Sorry, no.

A "decoupling" capacitor is used to isolate portions of circuits
from each other. That is, to destroy the connection between them.

Notably, decoupling capacitors are used as local reservoirs of
electrical energy which will continue to feed a load when another
load causes the supply voltage to glitch.
---

Coupling a circuit via a capacitor is just that, coupling. how ever,
using a CAPACITOR to isolate DC voltage (which is where the original
contents of this started) is termed as Decoupling capacitor which is
more to describe in what it's doing and not what it is.

---
Sorry, no.

Decoupling capacitors are used to isolate (decouple) circuit
elements from changes in their supply voltages, whatever the cause,
while coupling capacitors are used to pass AC signals between stages
with different quiescent DC outputs and inputs.
---

Any one that has really been working in the field knows this how ever,
I find those that just sit there arm chair wise and recite text book
literature and proclaim to be experts are just ignorant to say the least.

Graham, or is it Mr. HAM? the little snake in the grass.

---
That's not fair.

You're trying to impugn Graham with your ignorant "philosophy", (but
not technically) not because _he_ was technically wrong, but because
he corrected you and _you_ don't want to be considered to be under
his thumb.

What do you think about that?


--
JF

 

[Bob Monsen]

"Rich Grise" <rich@example.net> wrote in message
newsan.2007.09.29.00.23.58.839000@example.net...
[snip phase vs inversion discussion]

Admittedly, with a sine wave, they LOOK exactly the same; this is
probably the confusion factor for those who don't know the difference
yet.

All time based signals can be expressed as a sum of sine waves. By
superposition, each of those sin waves have been inverted by your inverter,
and so they each 'look' like they are all individually 180 degrees out of
phase... are they?

The concept of phase only applies to a single frequency. But, inverting a
signal appears to change the phase of all components by 180 degrees...

Turns out that there is an old psychology experiment, in which folks went
around wearing glasses that made everything look like it was upside-down.
After a few days, they got used to it, and everything looked right-side-up
with the glasses on, whereas when they took the glasses off, everything was
upside down. So, the question is, are you currently seeing things right side
up or upside down?

Are your glasses half-full? or half empty? Which end of the egg should be
opened first? Are you a big-endian, or a little-endian?

Pick your sides now. It is important to make sure you are on the right (or
would that be the left?) side.