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Help with polarity


Stephen Shauger

Jan 1, 1970
I would appreciate help with a problem.

I am trying to install a "CD to Cassette Adapter" and a "Portable CD
Power Adapter" to my car which has a tape deck.

The Power Adapter (Phillips #72488) says to set the polarity on the
plug so that the word tip lines up with either the "+" or the "-" if
the polarity of the portable CD player's polarity is positive or

My portable CD player (Sony Discman D-111) has center-point positive
polarity. I.e. the diagram looks like this.

+ ---0)--- -

So my question is: Is "center-point positive" the same as "positive"?
In other words, when the instructions on my power adapter refer to
positive polarity, are they refering to the center point or to the
outer wall.

Please reply to email [email protected]

Thank you so much for your help.



Jan 1, 1970
So my question is:
Is "center-point positive" the same as "positive"?
Aligning the correct polarity symbol
with the side of the plug receptacle marked "tip", they mean measured from the wall?
Stephen Shauger

Everybody needs to start using the same terminology.
On a 1/4" phone jack, starting from the center,
it goes tip, ring, sleeve.
On smaller phone jacks, too small for 3 elements,
it's tip, sleeve.

I've never heard a standard call-out on coaxial connectors
which have a hollow center on the male plug.
I say center conductor, sleeve.

"Wall" is never used.

That said, things are generally referenced from the sleeve,
since it is most likely to touch the chassis or "ground".
So, yes, you called it right.

Rich Grise

Jan 1, 1970
[email protected] (Stephen Shauger) wrote in message
So my question is: When the instructions to my power adapter refer to
"positive" and "negative" polarities with no other context given, do
they mean "center-point positive" and "center-point negative"
polarities? Or do they mean measured from the wall?

Thank you,


One way to find out for sure is with a voltmeter. :)


Sir Charles W. Shults III

Jan 1, 1970
I think you are analyzing this WAY too hard. Positive is positive, period.
There is only one center point. It can only be negative or positive.


Chip Shults
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