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

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?

Really, well there is another way to look at that.

imagine a CT (center Tapped) xformer where the CT is the common. both X1, X4 (X2 and X3 being joined as the CT) are now 180 degrees out of phase from each other with respect to common.

Both are in time with each other how ever, polarities are opposite.

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.

In the last example, using "phase" comparison isn't a proper way of explaining it, since you normally need two or more signals to compare against for evaluating phase shifts How ever!, if you were dealing with bridged circuits, then you could say, one output is out of phase 180 degrees from the other. Since both outputs can be measured with respect to common, this is just the same as the first example.

I think I broke that down simple enough.

In case you didn't see my other reply. You need 2 of more signals to say that one is out of time(PHASE) from the other. In the case of for example, AC wave form (sinusoidal). Using the term PHASE shift normally refers to comparing one reference with another at the same time. The closes example I can give that you may understand is a bridged Audio amplifier. the outputs are 180 degrees out of phase because they are from 2 difference sources that can be measured with with respect to common. With amplifier circuits that use a common for one of the speaker terminals generates only 1 output ref. You have nothing to compare it to that has the same signal applied.

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.

Hope This Helps! Rich

THEY ARE NOT OUT OF PHASE!!!!! They are opposite ends of THE SAME SIGNAL!

If you continue to believe that the two ends of a transformer winding are "out of phase", then please point out where the phase shifting takes place.

Thanks, Rich

In that specific instance they could be either one of the other. Where a circuit inverts a signal it's better practice to call the signal inverted than '180 degrees out of phase' since it describes better what's happening.

Indeed.

Graham

What a load of drivel.

Don't you ever feel embarassed writing such junk ?

Graham

Yes they are, by 180 degrees, which is what you want in the amp type being discussed.

Either in a phase inverter stage (Yes, that's what it's called), or in an interstage transformer, where the center-tap is common reference for both stages being driven.

You're such a smuck.

You must of been a real prize in your day.

Do you?

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

???

He's not dead, putz.

You mean "have been".

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

Graham

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

Graham

So, you never read what you post?

Yes, as sin(x+180°) = -sin(x)

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.

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.

:)