I have few units of 24V 3A output smps power bricks. I'm planning to mod one of this to generate 12V at least at 5A for my LED strips.
My idea is to tap two wires from the secondary winding of the 24V unit chopper transformer. This should give me high frequency AC which I can feed into another self made transformer, wound on ferrite toroid. The secondary of this transformer should have half number of turns but at least doubled wire diameter (compared to the primary) to generate 12V at 5 Amps.
After rectify and smoothed the 12V, regulation loop can be closed by sending the correct DC portion to the controller of the 24V smps brick so that it remain stable.
This scheme, if viable, will give me the freedom to wind required turns for any voltage I need for all my other projects.
My question is, how do I determine the wire diameter and number of turns for the primary of the toroidal transformer which I intend to built?