Current limiting circuit (300mA) with little voltage drop

[gmarocco]

I would like to reproduce using a 24V battery in order to test a device a solar panel that delivers 18-19V with a maximum current of 300mA. I have built a regulator using the L200 IC with both voltage and current regulation: when the load required more than 300mA the output voltage dropped to 12V. I have also built a current limiter using two PNP transistors but again the current was limited and the voltage dropped to 10.5VView attachment Current regulator.bmp
I wonder if there is a system for delivering a maximum value of the output current without changing so much the voltage drop

 

[schmitt trigger]

when the load required more than 300mA the output voltage dropped to 12V. I have also built a current limiter using two PNP transistors but again the current was limited and the voltage dropped to 10.5VView attachment 103896

That is precisely how the power supply should work. It is in CONSTANT VOLTAGE mode from zero to full rated current. Upon exceeding that limit, it works in CONSTANT CURRENT mode and the voltage drops to whatever value that current produces across the load resistance.

Let's say you put a 15 ohm load on the output. The resulting voltage will be 0.3 X 15 = 4.5v