Transient problems on the 0-30V 0-3A supply

[liquibyte]

I'm going to be using an LM35 based circuit to monitor the 0.47R sense resistors which are the components that get the hottest when under full load.  Based on tests I've done with the supplies I have built, the 2N3055's and the sense resistors themselves are the only components that get hot enough to require active cooling so that's what I'm going to do.  Everything else that gets fairly warm is on a decent heat sink.  The circuit itself adjusts the fan speed based on the temp it's measuring so that with little or no load, the fans are fairly quiet.  The simulation fairly accurately mimics the real circuit as far as power goes so I'm confident in the decisions I've made.

[Andy Watson]

I can never get testing results from someone that knows how to do it right.

May be, just may be, "someone that knows how to do it right" wouldn't get as far a testing it before going back to the drawing board. Just a thought

[liquibyte]

I can never get testing results from someone that knows how to do it right.

May be, just may be, "someone that knows how to do it right" wouldn't get as far a testing it before going back to the drawing board. Just a thought

Why?  Because it's not an overly complicated switcher?  Maybe because it doesn't have a microcontroller?  It's funny that you think along those lines but don't really offer why or advice to something better.  There's lots of that that goes on here and, frankly, if everyone thought like this then how would we learn.  So, you say it's bad and that even on paper its flaws can be pointed out.  Care to?  I've gotten a few ideas here on what to look for to fix this issue and I've actually managed a solution I think that can work around the flaws.  I came to these conclusions based on the advice I did get and yet I still won't stop messing with this because a few people keep telling me it's a bad design.  Why?  See the pic (thanks DH).  I see similarities in that design here and this was a production unit.  Sure, it got superceded but somone with a degree designed it and it sold.  Are you telling me that the company that produced that design was full of incompetent engineers?  All I want to do is understand what is going on enough that I can either work around it or correct the flaws so what I see now isn't happening anymore.

I want to thank everyone that has helped me to try and understand this circuit.  I can't say that I could do a better design on my own but I can say that I have learned a ton from all of the conversations on this board and from those members in particular.  Tim and David especially have a way of explaining things that make me spend hours doing research so that I grasp better what's going on.  I've fully caught the bug and, for what it's worth, I won't give up on this until it's completed.  That's why I come here.

[liquibyte]

I'm sure that some of the more experienced folks have been having a laugh at my mistake.  I failed to account for the cap holding the relay open which basically rendered it non-functional in this regard.  A couple of resistors and a transistor fixed that.