For the LM317 there is a precision current regulator circuit. This circuit uses an LM317 and only one resistor between the out and adjust pins. The operation of this circuit completely satisfies me, since I do not need to regulate the voltage, but I need more current than 1.5 A.
How do you recommend doing this? In all the suggested circuits there is also a part for voltage regulation, which I do not need; only current is needed.
I have seen proposals for parallel connection of LM317s, but not everyone approves of this, and there is also a part for voltage regulation.
My idea is to use an LM2596-ADJ as a low-loss voltage regulator and after that use an LM317 for current limiting. At the same time, I will place the connection point of the feedback output already behind the LM317 output. But the whole problem is in the maximum current of 1.5 A for the LM317. I need about 2.7 A to charge a battery.
UPD: I have seen circuits using PNP and NPN transistors, but there is a voltage adjustment using LM317. I want LM317 to correct current only, and 2596 to control voltage.
Now my diagram looks like this. I did not buy 2n3906, but I have bc327 and bc557. Perhaps there is a problem with them, or this circuit is not designed for a battery. According to the recommendations here, I abandoned the lm317.
Now the problem is that I set the voltage at idle, and when I connect the battery, it goes down and the current also becomes less. If I increase the voltage with the trimmer, the current also increases. But as the battery charges, the voltage increases and the current, respectively, also increases. They probably want to reach idle values.