1 - LM358 dual op amp or lm741 single op amp.
1 - irfz44n mosfet
2 - 1 k resistor
1 - 68 k resistor
1 - 1 k pot
1 - 5.6 volt zener diode
Connect only the 5.6 volt zener to the ground pin
Of the lm358 or lm741 op amp.
Connect everything else as shown.
This circuit works just like the lm2596 board.
