Is there any thing wrong with this design
 

Dear All,

I have a question with this design for PS

The input is 320 V AC and the out put is 400V DC

I am wondering why Resistor #5 (68K 3W) always very hot?

Can some one give me some clue?

tks

what is the dissipation of that Resistor #5 (68K 3W)? in my case, i use that 3 watt to dissipate less than 1 watt...

Does it actually work at all? I really don't see how you could subject an LM317 to these voltages. How could you send AC straight through a 10mH inductor? What happens if you put 100uF straight over AC? Where does the DC come from? Etc.

That was my initial thought, too, vac. But he has a rectifier box there on the AC input. I don't understand the zener bypass, or the pot wiper to nowhere, or...
so best for me to leave it alone.:)

Sofaspud,thanks, had overlooked it. And you are also right about your last point.

the zener could be a 27volt one, together with the mje13005 ensures that the vin-vout rating of the lm317 is never exceeded....

Sure. I should've realized. Thanks, Tony.

welcome, the circuit reminds me of the maida regulator....http://www.diyaudio.com/forums/tubes...regulator.html

You are completely right!

LM 317 adjust pin is 1.25 V below output V. R5 dissipates about 2.35 W = (400-1.25)^2/68000.

The 5k pot is much too large. For 400 V out you need about 213 Ohms there, so you will be using only 4% of the pot, voltage adjustment will be way too sensitive.