Primary winding

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Drmario5237

Joined Oct 14, 2018
65
When winding the primary coil of a transformer what determines how many turns in the coil you make per how much voltage/amprages the coil is going to be hooked to. Is there a formula for this. I understand that ratio formula for primary to secondary but how many windings do you need to start with in the primary. Thanks
 

MaxHeadRoom

Joined Jul 18, 2013
19,449
There is no De-facto source of information in transformer manufacturing.
Are you thinking of making one? Or rewinding?
The typical turns/volt is ~ 4-5 turns/volt for EI versions, and 2.5-3 for Toroidal types.
Max.
 

Thread Starter

Drmario5237

Joined Oct 14, 2018
65
There is no De-facto source of information in transformer manufacturing.
Are you thinking of making one? Or rewinding?
The typical turns/volt is ~ 4-5 turns/volt for EI versions, and 2.5-3 for Toroidal types.
Max.
.

I'm getting me a kit to make a transformer and want to see what will happen if I add a third winding to the transformer that feeds off the secondary and take what that third winding produces and dump that back into the primary winding with my output coming off the secondary winding
 

Thread Starter

Drmario5237

Joined Oct 14, 2018
65
A article I read said if you have two primary winding hooked together in series the voltages add up so if I have a 1 to 3 ratio of primary to secondary and a 3 to 2 ratio of secondary to third run the third though resistors so the transformer doesn't over heat and run the third back into the primary using some zenner diodes in the input to the primary so the current from the third won't go back to ground till the primary adds the voltage up enough to effect the backlash on the zenner diodes and use whatever I get from the secondary as output I've accomplished in reading the voltage and amparage output instead of trading voltage for amparage or visa versa according to if it's step up or step down. This will help me with something else I want to build
 

MaxHeadRoom

Joined Jul 18, 2013
19,449
The two winding's in series have to be in phase, IOW, the end of the first connected to the start of the second.
What exactly are you trying to achieve?
Max.
 

MisterBill2

Joined Jan 23, 2018
4,562
You are not going to "put energy back into the primary", that does not happen. It is always possible to put another winding in series with the primary to vary the effective number of turns. In fact that is done on a number of higher quality pieces of equipment so as to compensate for the local mains voltage being a bit high or low. But if you put two windings in parallel that do not have exactly the same number of turns you are effectively creating a short circuit and the result will be excessive power dissipated inside the transformer, usually resulting in burned insulation and a smelly smoking failure.
The number of turns is usually set to bring the core magnetization short of the point where more flux does not provide more magnetization. This is done to avoid magnetic core saturation, which wastes energy by converting it into heat. And the core size is mostly selected to provide enough iron for the amount of power desired from the secondaries. So the very first step in designing a transformer is to know what you need to get out of it, both voltages and powers from each secondary winding. There are a number of serious texts about designing transformers that will explain it all and also provide some math to explain those explanations.
 

Tonyr1084

Joined Sep 24, 2015
3,942
When I was a child I understood electricity to flow through a cord. An extension cord (according to my thinking) was that if you plugged an extension cord into the wall with a lamp at the other end, turned the lamp on, then super duper fastly unplug the cord from the wall and plug it into the end of itself then the current would flow in circles all the while lighting the lamp. For free. I still haven't gotten that one to work. I'm beginning to think it never will.
 

MisterBill2

Joined Jan 23, 2018
4,562
A reminder:
We are not allowed to discuss over unity projects. Transformers yes, over unity no.
I believe that the intention of that post # 9 was to be funny. And there have certainly been enough of those "over unity" questions in the past few months that went on for quite a while. So how about just flagging them and allowing explanations of exactly WHY they are "over unity" and can not possibly work?
 

Tonyr1084

Joined Sep 24, 2015
3,942
Had a cousin who insisted you could take a tube and wrap a coil of wire around it then move a magnet to generate electricity. Yes, that will work but he went on to say that you can add extra coils and get free energy. I never was able to convince him that the extra coils would require extra power to move the magnet in the tube. He insisted to his dying breath it would work. He never succeeded.
 
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