A Complete 13.8 Volt, 50 Amp Power Supply

[petcnc]

My only goal to put more power transistor is to decrease the heat per transistor. Because I assume that if I put 6 x 2N3771, the heat will be lower than with 4. Do I'm wrong ?

When drawing 50 amps continuously the transistors will run fairly hot. Think of the pass transistors as big variable resistors, as this is what they are really doing.
A little math shows the problem. For my design, I have an unregulated voltage of 22 volts and the load is 50 amps. Ohm's Law shows us that: 22 volts minus 13.8 volts = 8.26 volts drop across the pass transistors. 8.26 volts X 50 amps = 413 watts of heat to be dissipated!
No matter how many transistors you use the amount of heat to be dissipated is the same!
Of course it is shared amongst more transistors but you need bigger heatsink as well to make full use of the increased number of transistors!

 

[pottiera]

Haaaa yes, the total amount of heat will be the same ! Oupsss !!
So 4 or 6 will change nothing.
Thanks again