Would this be a real neutral?

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As a side note:

With audio amplifiers, one can use a phase splitter (which creates a dual-polarity signal from a single signal. This is as simple as feeding a transformer with a single-ended primary and a center-tapped secondary (sound familiar?) to feed a 'push-pull' output stage.

One can also use a transistor phase-splitter to drive two mono amplifiers in bridged mode powering a single speaker. This effectively doubles the output voltage (sound familiar again?) which, if the amplifiers are capable of it, quadruples the available power.
 
Larry

Its been a while since those days.

But if my memory serves me right the main purpose of the push pull type audio
amp. was used because you don't have to maintain a forward bias on your amplifying components Tubes or Transistors like you do the single ended Amplifiers. There by
lowering the power required from your B+ circuit.

But they do give better Fidelity.

They also called the inputs for these amplifiers as being out of Phase, but in reality they where not the two driver outputs derive for the inputs where just of opposite polarity.
in reality they are in sync. This is why some in the Electrical field call the secondary of a single phase transformer as being out of phase. :)
 
081115-1215 EST

There are various classes of amplifiers, A, B, C and today D.

In a class A amplifier the bias is such that the amplifier is always conducting. This results in a lot wasted power.

A class B amplifier will be biased so that approximately 1/2 of the time the amplifier is off. By using a pair of amplifiers, tubes or transistors or whatever, one can output both halfs of the input signal, negative and positive, and still accurately reproduce the input waveform. This is done with the push-pull or equivalent method. Rather than use a pure class B mode the bias was usually not set at cutoff but somewhat above and the amplifier was called class AB.

In all these cases negative feedback is used to reduce distortion and improve quality.

Class C amplifiers conduct less than 180 degrees. These are biased below cutoff and are typically used for RF amplification of FM signals or unmodulated signals. This is basically a pulse driver to a resonant circuit.

Class D amplifiers are a pulse modulated amplifier and are basically an on-off switch driving a low pass filter.

I have no problem with the terms phase inverter, phase splitter, out of phase, and 180 phase shift. I like phase inverter for audio amplifier useage. Context has a lot to do with with how I would describe the two outputs of a center tapped transformer for a power system. On Tektronix oscilloscopes the term Invert is used.

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ronaldrc said:
Rattus

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Mark

Larry is right it has to be wound on the same laminated steel core of the transformer to work.It is the same as one winding with a center tap, to work as the autotransformer.

You are thinking right you will not get this effect with two transformers.
There is no phase shift here everything happens at same time, you can get a polarity change from the primary to secondary of course we are not using it. :)
Click to expand...


I need to make a correction here I think in the 240 volt input verson two transformers would work? What do you all think? :)
 
I think not Ronald:

I think not Ronald:

ronaldrc said:
I need to make a correction here I think in the 240 volt input verson two transformers would work? What do you all think? :)
Click to expand...

Half the load current flows from L1, thru the load and the lower half of the xfmr. This same current is coupled to the other half of the transformer which provides the other half of the load current.

Two xfmrs would result in an inductive voltage divider.
 
081115-1228 EST

ronaldrc:

Going back to your drawing of post #32 there is a real world problem.

The center tap of your autotransformer may and probably will be at a differential potential than the center tap of the utility transformer. This means at least some of the time there will be load current flowing thru the ground path back to the utility transformer center tap.

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gar said:
081115-1228 EST

ronaldrc:

Going back to your drawing of post #32 there is a real world problem.

The center tap of your autotransformer may and probably will be at a differential potential than the center tap of the utility transformer. This means at least some of the time there will be load current flowing thru the ground path back to the utility transformer center tap.

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Click to expand...

Gar THanks

I isolated the ground if theres any more like that I will correct them. :)
 
Gar

After I studied the circuit it would have been a paralleled neutral instead of a ground.
Not Taking voltage drop into consideration it would have been conducting half the load of the neutral all the time.

Thanks :)
 
081115-1313 EST

ronaldrc:

Still referring to your drawing of post #32.

If you have only two wires, L1 and L2, both hot, from the main panel to the garage and nothing else except earth resistance, maybe 10 ohms, between a ground rod at the garaage and the main panel, then the current in the ground path will be the voltage difference between main panel neutral and your garage neutral divided by the ground path resistance. For a voltage difference of 5 V and the 10 ohms this will be 1/2 A.

This voltage difference will be a funtion of the internal impedance of the transformer, line resistance, and distribution and amount of load current.

If you ran a real neutral from the main panel to the garage there would probably be less voltage difference most of the time.

Now consider this:
Three load wires to the garage L1, L2, and N. The distance is 100 ft and the three wires are #12 copper. You have a 1.5 HP radial arm saw connected for 120 V. Startup current is 80 A. You also have a computer in the garage directly connected to a computer in the house via RS232. Both computers have 3 prong cords and thus their chassis are connected to their neutrals via their EGCs.

The neutral wire resistance is 0.16 ohms. The voltage drop on the neutral during startup is about 0.16*80 = 12.8 V. This will create data errors in any communication at the startup time.

12 V probably won't damage the computer components. If you put a direct short from neutral to one hot wire the voltage drop across the neutral will be about 60 V and the peak of this is 84 V, and this will cause at least RS232 circuit damage. Your autotransformer method would probably make the effects worse.

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