^^I don't actually know since the original plug was a ciggy lighter plug which i'm pretty sure is +12v right???

This booster looks Chinese.... can any Chinese on here confirm if cars in CHina are -12v??

I have 3 of them so i'm experimenting on 2... 1 of them i simply reversed the transistors... seems to do something but i'm quite confident it will blow.... the other one my dad installed some NPNs that go the same direction as the original plus we reversed a capacitor that was also wired in the opposite polarity.

Now I have some intermediate knowledge of electronic components and assembly and by following the circuit a bit i've tried to understand it but admittedly i'm not sure of the outcome or the consequences of what i've done... the reversing seems to be working where as is before didn't do much...

***EDIT***
if anyone is interested I could take photos of both sides of the board and possibly draw up a schematic variant in case people can get it to work themselves and use it for their purpose?