/diy/ - Do It Yourself

>>1104240
>1
you can use a larger core. it'll allow you to use thicker gauge wires and will decrease both magnetic and copper losses.

>2
here's the order of determination:

Np (primary turns) = V/(4.4*f*Bmax*Acore)
Ip (primary current) = Pout/Vin_min
Np*Ip^2 ∝ required winding area, same for other windings

if you decrease Np you have to increase Acore or f (hello smps), or else Bmax (peak flux density) will increase. B saturation for iron/steel is 1.5 to 2T. approaching that limit is okay for mains freq designs because magnetic losses are low proportional to core size, but if your calculations don't account for parameter tolerances then you can get core saturation and then you'll be really fucking mad that you wound all those wires for nothing.

>3
there's no reason not to prefer a tertiary winding to a secondary tap unless you're limited in how many wires you can run to and from the core.

addendum: get an E core and a nice wholesome bobbin. toroids are for masochists. if it's not already obvious, buy magnet wire. if you're using standard insulation you're wasting a ton of winding area.