Hi I have dozens of surplus PC AT/ATX power supplies and I am in the need for a power supply for a project (audio amp) with a voltage greater than these psu can supply and I want to put some use for them, so I decided to build from scratch, and rewind the EE cores for the output needed.

Now I´m wondering if 2 or more transformers can be driven in parallel for greater output power or do I have to build separate psu´s and place the outputs in parallel.

Ok so if you can give me some insight as to some of these points I would greatly appreciated.

1. How can I use 2 or more EE cores for greater output power?
2. What topology is best for this project ?
3. Do I use single or separate set of driver and switch to drive all the transformers.?
4. what is the highest or recomended volts/amp ratio I can get from these cores.?

 

You stuck the cores together so you end up with a big core with large cross sectional area. Like in the image which I saw somewhere on the NET. Sorry I can't remember where now.

Then you have only one transformer to worry about.

Attached Thumbnails

 

__________________
L.Chung

 

the short form is you can't.

even a switcher guru could not do anything with those. you do not know the material or the gap. the only thing you can do safely is to remove secondary turns but that is going the wrong way.

The only thing that makes sense for you to try is to put the primaries in parallel and the secondaries in series and make adjustments to the rest of the circuit, also difficult to impossible to help with since you do not mention the amount of power that you actually need.

Dan

 

Hi thanks for the info!!

well I don´t have a special need, I just wan´t to put some use for them and then see on what projects I can use them in. also I wan´t to take the cores apart and start from scratch for this I have been doing some research and I think I could use generic figures for the material or permeability

hey! hey! the sticking the cores together sounds good can it be done with ferrite cores, I don´t mind attempting to rewind everyting just point me in the right direction so I can experiment with don´t mind safely, I´ve blown a lot of things up and got zaped many times....

I found some mention about here
Re: How to make cheap big cores?

 

Determine the ampere turns saturation point of the core by putting a current sense resistor in series and applying a current limited source to it. The knee of the curve where the current jumps to the limit is the saturation point. A good rule of thumb would be 70% of this current for a 25KHz switcher and 30% for a 100KHz switcher. Higher frequency materials up both values and you have no way of know what the material will handle until you power it up and see if it heat up at simultaneous high frequency and current density.

Dan

 

I'm searching for a SMPS project can you give me one,Please. I,m so interested to build one.Please help me.