I built this circuit and it's not working

 

I built this circuit View attachment 174679and it's not working

So you used an LM339 or LM393 comparator in the current-limit circuit?

Does the voltage regulator circuit work without the current limit circuit connected?

Did you double-check all the wiring against the schematic?

If you still can't get it to work, measure the voltages at all the connection nodes and post them on the schematic.

 

1)I used lm339
2)The regulator works without the current limit circuit
3)I checked the conections thousand times
4)Can you be more specific about which component shoud i mesure?
-also one thing i didn't mension that r6 is overheating is that because that is droping the 27 volts for the led not to burn or is that something wrong.

 

3)I checked the conections thousand times

Really.

4)Can you be more specific about which component shoud i mesure?

All the node voltages (any place with two or more connections) in the current limit circuit when it is connected but not working.
That's the only way I might be able to determine what's wrong.

r6 is overheating

It will dissipate about 200mW.
What's the wattage rating of the resistor?
A 1/4 W resistor will likely get too hot to touch. It should be rated for 1/2 W or more.

 

Really.

All the node voltages (any place with two or more connections) in the current limit circuit when it is connected but not working.
That's the only way I might be able to determine what's wrong.
It will dissipate about 200mW.
What's the wattage rating of the resistor?
A 1/4 W resistor will likely get too hot to touch. It should be rated for 1/2 W or more.

Oh mine it's 1/4

 

Below is the LTspice simulation of a current limit circuit you can add to your power supply circuit.
It allows adjustment from essentially zero (7mA in the simulation) to the maximum of 4.4A for the component values shown.
It uses a power-on LED, D1, to provide a voltage reference for the constant-current.
R2 can be tweaked to get the maximum current-limit you want.
D1 and shunt R6 should be connected to the left side of the circuit next to the supply negative.

With this the current limit circuit consisting of Q5 and R5 are not needed.

As you can see, the load current is constant once it reaches the set limit as determined by pot U2 (shown for wiper set points of 0%, 10% 25%, 50%, and 100%).

View attachment 174431

It should be noted that this circuit will oscillate with an inductive load. I think you can show that with the ltspice but I don't know exactly how to do it. Be ready with a bunch of capacitors!