Have a 12v power cable feeding from a small power supply unit here that has a brown wire and a blue wire, anyone confirm what colour is positive and what is negative ?? obviously dont want to get them the wrong way around !

cheers

 

Do NOT ask that question here

Google it

 

Yes, because even if the first two replies are both correct and in agreement, the third plonker will only contradict them.

 

Have you tried licking one of them

 

Either:

1/ Plug it in, switch it on, and stick a volt meter across the wires in question

2/ If you can get to the terminal connections on the power supply it should tell you on the board next to them.

3/ If you can't get to them, it should tell you on the supply unit's label.

If none of the above is possible don't use it, because power supply units from reputable manufacturers never have blue or brown low voltage DC cables

 

Id expect brown to be +12v and blue to be -12v, but as advised: check.

 

Correct and confirmed by google- sorry should have checked first !!!

appreciatte the advice folks,

 

I'd expect brown to be +12V and blue to be 0V actually - though there is absolutely no convention for low voltage wiring, manufacturers can and do use whatever colours they like in whatever order they like. There's no substitute in this case for measuring it with a meter.