TRANSFORMER CONSTRUCTION
I have a basic query about the winding of transformer. I have attached the transformer construction (TRANSFORMER_CONSTRUCTION.PDF) page from the design I made using PIExpert and also attached a drawing demonstrating two different directions of winding (TRANSFORMER_WINDING_DIRECTION).
Take an example of the Bias winding which has four turns, starts at pin #5 and ends at pin #4. A bobbin has 5+5 (total 10) pins. A winding according to the Figure 1 in the attached demo drawing will cross pin #5 and ends at pin #4. A complete winding is shown in Figure 1A.
However if you follow the Figure 2, although the winding start at pin #5 and ends at pin #4 the last turn will not cross pin#5. A complete winding is shown in Figure 2A. So in theory the last turn will not be a complete turn. Which method should we follow?
The legend below the Mechanical Diagram shows the winding direction "Clockwise" but I did not understand it properly. It depends upon how you hold the bobbin. I tried but did not find any movie or illustration on winding.
With best regards,
Madhuri
Comments
Thank you for the clarification. Now my only question is, looking at your reply I now understand that swapping the pins on the transformer for making it convenient on PCB layout would not be any problem. Is that right? In the other words, if it is a 10 pins bobbin, secondaries on the side from pin 6 to 10, if the PIExpert suggests Common on pin 7 and 5V on pin 9, I can swap and make Common on pin 9 and 5V on pin 7. Similarly the other pins used on the other outputs. Please confirm.
Regards,
Madhuri
It's pretty common and very helpful to choose the pin allocation on your transformer to help with the PCB layout.
Regards,
-The Traveler
Many thanks. That will help us quite a lot.
Regards,
I understand what you're asking and yes, technically, one setup will have slightly more turns than required and the other will have slightly less.
However, with how the transformer should be wound, these differences will be minimal. I've attached a copy of your PDF with a quick change to how the windings should actually be constructed.
Regards,
The Traveler