Polarity

[HappyDaiz]

Hello..I have bought a portable Dvd player from the USA and want to fit it in my car....it says to check the polarity, so does anybody know if a negative ground has a negative or positive polarity? I'm confused as it might be the opposite, and don't want to risk blowing the thing up!

[lisaj]

"-", "-ve", "negative" and "ground" are all negative terminal equivalents. Current flows from a positive (red) terminal to a negative (black) terminal. To be sure, use a multimeter set on the appropriate voltage meter setting and put the black probe on the supposed negative and the red probe on the supposed positive. If you're correct, the number displayed will be positive (above zero). If you're wrong, the number will displayed as negative (minus numbers, and below zero).

[cupra]

I Agree with lisaj - if you're not sure then check with a multimeter! Also be careful with some in-car devices from abroad - some manufacturers are starting to use non-standard batteries so make sure your car supply voltage matches the player (normally 12V but I have seen 24V before)

[ralph1953]

What we call "Earth", Americans call "Ground"; if the DVD player is "Negative Ground" it's "Negative Earth". All British cars built in the last 40 years or so are negative earth (ie. the negative terminal of the battery is connected to the body of the car) You say it's a portable DVD; does it have a cigarette lighter plug to use in the car? If so, and it says it's Negative Ground, and your car's not too old, it'll be OK to plug it in to the cigarette lighter socket... "Check the polarity" just means "Check which way round the battery's connected"

[TheheftyGeorge]

Ask experts.