http://electronics-diy.com/power-supply-lm317-2n3055-0-28v-6-8a.php

Bad circuit! The current booster is outside the voltage control loop, so it will have very poor voltage regulation.

 

Bad circuit! The current booster is outside the voltage control loop, so it will have very poor voltage regulation.

he isnt making that circuit,
its just showing him how to connect the power transistor to the Lm317, he's doing it his own way.

 

he isnt making that circuit,
its just showing him how to connect the power transistor to the Lm317...

That is what is bad about that circuit!

 

circuit like this would work, use a 2k5 pot, to give you 1.2 to 15v output. you can use the other transistor for current limit if you decide to modify it.

http://www.circuitdiagram.org/lm317-5a-variable-power-supply.html

 

circuit like this would work, use a 2k5 pot, to give you 1.2 to 15v output. you can use the other transistor for current limit if you decide to modify it.

http://www.circuitdiagram.org/lm317-5a-variable-power-supply.html

Another bad design because the current boosting transistor is connected the wrong way (outside the feedback loop). Dodgy, I know you have looked at the circuit recommended by National/TI right on their application notes, so why do you keep linking to these bad internet circuits invented by clueless newbies?

Right off the website to which you linked: "On internet you will find thousands of electronic circuit diagrams some are very good designed and some are not. So you have to modify them to make them according to your needs but some circuits are ready to make and require no changes."

This local forum thread shows the right way to do it. Another, that went on for pages and pages.

 

Mike he wants to use the 2n3055 in his psu, which can be used that way as per datasheet, with a current limit transistor, so wait until he comes back with what he wants to do.

 

Mike he wants to use the 2n3055 in his psu, but he would be better to re design the output side, i am not giving him bad circuits, just ideas how to mod it.

Then the correct way of retaining the 2N3055 is the way I showed in post #14 of the linked to thread.