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Cigarette lighter quickie...

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grrr_arrghh

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Hi.

It seems to me that the plugs that go in car cigarette lighters could be put in the wrong way round. Presumably then, the sockets and plugs must have diodes in so that it will work whichever way round you put it, yeah?

So, if I bought (for example) this **broken link removed** would I have to worry about the above stuff, would it be built into the plug, or would I have to add anything to my circuit?

thanks

Tim
 
grrr_arrghh said:
Hi.

It seems to me that the plugs that go in car cigarette lighters could be put in the wrong way round. Presumably then, the sockets and plugs must have diodes in so that it will work whichever way round you put it, yeah?

You can't plug them in the wrong way, because one contact is on the outside, and the other on the centre. There's no polarity protection of any kind built in, they are actually extremely crude connectors.

Although you can't plug them in the wrong way, in my experience I've seen the actual sockets in the car wired the opposite way at times - I never plug anything polarity sensitive into one without checking it first.
 
oh year, I forgot about the metal tip! lol, I was thinking of the two sprung bits on the outside, I was thinking each was a different contact. Oh well, I'll think a bit more carefully before i post next time!!

interesting what you say about the sockets, Its hard to believe that manfs could be that carefree... my circuit has a diode on the +v supply, so the worst that will happen is it just won't work.

Cheers

Tim
 
grrr_arrghh said:
interesting what you say about the sockets, Its hard to believe that manfs could be that carefree... my circuit has a diode on the +v supply, so the worst that will happen is it just won't work.

I don't think that it's a question of being 'carefree', I just thing there's no standard way of connecting them?. Don't forget, it's designed as a lighter socket, there's no need for it to have any particular polarity for that use.

You wouldn't believe the number of portable TV's that we get brought back that have been connected the wrong way round - I've checked lots of cars over the years for people. Caravans are far worse! - the internal wiring is often too thin to even work a colour TV!.
 
Carefree mfgs??? You forget the origins of the cigarette lighter plug! It was designed in, what, the 40's or 50's (maybe earlier?) for one thing and one thing only- being a cigarette lighter. Not an accessory connector! It works well enough.

We keep the convention just for backwards compatability to the existing socket. Can't add any funky plastic connectors & new contacts to the socket either, since it's still designed to accept a red-hot cigarette lighter heating element whether or not it ever gets used as such.
 
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