OK, I'm learning something here. Based on another thread I've come away with copying someone else's work and manipulating it to this:

I don't have a circuit or a need for such a circuit. Just want to know if I've got this right. The thinking is a Constant Current that can be varied, followed by a Constant Voltage, which can also be varied. I have NO IDEA if this is right or will work. Change anything you think would help me understand this better.

No, not school work, not for a 67 year old guy who never went very far in electronics. My career has been along the lines of electronics inspector, but I hobby in electronics. Would like to know if I'm on the right track with this.

Again, this is from someone else's work. Not trying to take credit for anything. Just want to understand better.

 

I have NO IDEA if this is right or will work.

Sorry, but that pot is varying the maximum (regulated) output voltage of U1, not its current limit.
R1 determines the current limit.

 

OK, but on the other thread; post #7 below, that's what I based my copy off of.

Other thread, post #7 below

Now that I look closer at MY rendition I see a mistake I made. Will redo my drawing.

 

Right track now? Or am I starting from a circuit that doesn't do what I think it is supposed to do?

 

You cannot have CC and CV at the same time.
CC and CV are both limits.
First one that trips wins.

If CC trips, the voltage must fall.

 

View attachment 339645
Right track now? Or am I starting from a circuit that doesn't do what I think it is supposed to do?

Nope, still same side-track.
Doesn't do what you think.
You now have a circuit where U1 have a variable output voltage and fixed current limit, and U3 has a variable output voltage.

If you look at the "LM317 as a current limiter control" thread, I posted a LM317 circuit with limited current-limit control.

 

Backing up just a bit - - - Is this a Variable CC circuit? Or is it something else? What Frankenstein have I created? (on paper)

 

Backing up just a bit - - - Is this a Variable CC circuit? Or is it something else? What Frankenstein have I created? (on paper)

It it a CV circuit with the pot controlling the voltage, and a current-limit determined by the value of R1.
The current limit is not variable other than by changing the value of R1.

The sim of that circuit is shown in the other thread.

 

It it a CV circuit with the pot controlling the voltage, and a current-limit determined by the value of R1.
The current limit is not variable other than by changing the value of R1.

Thanks. Will have to make careful notes of this. Next time I need a variable PS - - - whenever that may be, I'll hopefully retain some of this info.

Tony.

 

Certainly there are a lot of commercially available power supplies available that provide both a well regulated voltage AND an adjustable fold-back current control. BUT not at the same time! That would violate reality!!

WHAT THAT MEANS is that such a supply will hold the output voltage constant UP TO SOME LIMIT, and above that current limit, the voltage will drop to hold the current at that limit. This function is quite handy for development projects, as well as being very useful as a protection system in equipment subject to occasional overloads from assorted causes. It is Much Less disruptive than halting production while a circuit breaker is reset or a fuse gets replaced.
I have well over a hundred of those supplies working for happy customers for many years.