Sir Hammez . . . . .
You say . . . .
I have a 30w USB-C laptop power supply.
Now, to potentially be of more help to you, on your situation can you give us further exacting details.
Is the situation being that this specific 30w USB-C laptop power supply that you now have, is just being a cast off supply, gifted from a friend, curbside find, flea market or thrift store item?
Otherwise, it is not one that is normally dedicated to normal use of a laptop that you have . . .or other ? equipment of yours ?
If the situation is that you have it and now want to use it as a stand alone item and and want to " permanently" convert its 5V ? amps ? output to 12VDC instead.
Can you give its brand and model number and any specs of voltage and current capability at each voltage output level being printed on its case..
Visually . . . . . does it look like access to its circuit board innards within the case is possible . . . . or it is having an ultrasonically bonded case and will require cutting open its case ?
What will this newly acquired 12VDC output be powering and at what max amperage current consumption ? . . . . with particular interest, if its being an AM radio ?
Thaaaaaaassssit
73's de Edd.