Before I blow up my mount :)

[LewisM]

I am an electrickem noob - total noob.

I want to make an adaptor to go from a regular cigarette adaptor with a 2.5mm plug coming out to a Vixen Sphinx Starbook (which uses a proprietary power plug grrr....).

The Sphinx connection is centre +.

By standard, are cigarette lighter plugs centre +, therefore the centre of the female 2.5mm jack centre + too? (I have packed my multimeter so can't check).

[LewisM]

Thanks for not looking

Anyway, I completed it, and the polarity was correct. All working fine.

[glend (Glen)]

I looked. All those connectors are + on the centre (tip) contact. It's always a good idea to have a fuse inline on the + somewhere. The cigar lights plugs usually have a fuse inside (probably 10amp).

[The_bluester (Paul)]

And yes, the lighter sockets are center positive. The outer used to be screwed to metal parts of the body and provided the ground reference.