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Old 09-03-2017, 09:03 AM
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Netica Netica is offline
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Join Date: Jan 2009
Posts: 151
Questions about Al's presentation regarding transformer

Hi Aaron,

Thanks to Al, Aaron and all invloved for making this video and information available.
It is great to have this new insight into this EV gray power supply transformer.

I am confussed about some aspects of the transformer and need some clarification.

Questions about E V Gray transformer in the power supply.

1/ Primary winding, just to understand.
The two primary wraps of copper look as if they are wound in same direction from pictures of the actual winding 38.50 on video and page 110 and 111 on presentation slides. Yet the diagrams he shows are shown to be in the opposite direction 40.04 in the video and page 114 on the slides. Are the diagrams on the slide done in a way of view from top and view from bottom? So really both the windings are effectively still going in the same direction and orientation.
So looking only from the top both windings would start and be wound in the same clockwise direction.

2/a. It is hard to understand how the secondary coil is wound going by the diagram on video at 42:31 and on the slides at page 125 and 126 The part I don't understand is that between every second layer of windings instead of just a continious connection there are leads that go outside of the coils to respective sides and back in again. Its broken up into 3 seperate double layers connected together outside of the coil. I just don't see or understand why this outside lead is done this way and what purpose it is for?

2/b. Also the best I can make out as far as windings go on the secondary is that one channel is wound in one direction and the other is wound in the opposite direction so all 3 double layers are wound in the same direction on each channel. Do you know if this is correct?

2/c. Can Al give the direction of the secondary winding of the inner channel and the outer channel with reference to the primary winding direction.

3/ Not having insulation between the windings of the primary seems unusual as they would mingle and just act as one winding I would think, Do you or anyone know why it was done this way?

4/ What kind of insulation is being used between all the windings and between primary and secondarys.

5/ The circuit diagram has a mistake in it as far as I can see. Where he shows the negative side of the primary there is a diode. He has drawn it in what I consider the correct orientation on Pages 112,113,114,115. showing the primary. But on the circuit diagram, pages 143 and 145 The diodes are the incorrect way around. The other diodes there arn't correct either and there's no way for the primary to conduct when the transistors switch on. Also the collapsing field needs to go back to the capacitors but the two D1 diodes won't let it occur as they are the wrong way around aswell.

6/ Looking at the bridge rectifiers on the drawings on page 125 and 126 the output for the secondary, all the diode symbols are shown the wrong way around, or the + and - are the wrong way around.

Is it possible to get Al to re-explain and clarify the things that I have brought up.
Maybe you could pass these questions onto him and get the answers and post them or maybe he could answer them in this forum.

Thank you,
And thanks for help.
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