Adjust the voltage at the top middle left upper voltage source and see result in LED display.
Max 255 v
Diplay is hexadecimal so convert it into decimal..
So for 255 v it gives FF
For 60 volt it gives 3C
(Notes: 3C means 3*16+ 12 = 60 volts
FF means 15*16 + 15 = 255 volt)
:-) :D
And it is bidirectional and flutuates so take a high value.