help designing regulated PS 13v8@50A w/ IRFZ44

[Enzo]

I suspect he won;t be dropping the entire 13.8v ACROSS the transistor.

[kroto]

I think that will be:
15*1,414= 21V (assuming the V_ripple not high)

Pd = Vin-Vreg*Iout
Pd = 21 - 13,8 * 50 (max)
Pd = 360W.

but how to use MosFET (HEXFET)?

[Enzo]

I was being academic. 690 watts or 360 watts, how do you intend to dissipate all that power from one little TO220 transistor?

[kroto]

paralleling of course, HEXFET is more rugged than BJT isn't?
so Pd max of 35W/pcs I think that was suitable.
360/35 = 10,28 or 10 pcs.

[star882]

Make a buck converter and you'll only need to use 2-3.

[wg_ski]

Originally Posted by kroto

I think that will be:
15*1,414= 21V (assuming the V_ripple not high)

Pd = Vin-Vreg*Iout
Pd = 21 - 13,8 * 50 (max)
Pd = 360W.

but how to use MosFET (HEXFET)?

At those current levels, a 15-0-15 trafo will give you closer to 15V DC out. Unloaded it will be 21. Dissipation will be significantly less, but still it would be a problem. I'd be more worried about a linear regulator dropping out than anything else. Star's idea of the buck converter is probably the best way to go about regulating this.