• Re: What percentage of power supplies have a negative inner?

    From GB@21:1/5 to Mike Halmarack on Sat Dec 7 10:25:38 2024
    On 07/12/2024 10:09, Mike Halmarack wrote:
    My router power supply died. I got a new one. I also got an adjustable voltage power supply with 34 interchangeable heads from eBay, to avoid delivery waiting times in case of future power losses.

    Reading up on the subject, I was cautioned to ensure the polarity of a device's supply, indicating that these tend to vary.
    On enquiry to the variable power supply provider I was told that "all
    the interchangeable heads are positive" which I don't think is a very helpful answer.

    There appears to be no facility to ensure the polarity of each head
    without test equipment. This, nor change the polarity of the heads by
    any means.
    Is this because a negative inner is too rare to provide for?

    I have one with a switch to change the polarity. I therefore assume that
    both polarities are needed.

    --- SoupGate-Win32 v1.05
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  • From Andy Burns@21:1/5 to Mike Halmarack on Sat Dec 7 11:44:39 2024
    Mike Halmarack wrote:

    I was cautioned to ensure the polarity of a
    device's supply, indicating that these tend to vary.
    On enquiry to the variable power supply provider I was told that "all
    the interchangeable heads are positive"

    The generic wall-wart I have, is switchable 3/6/9/12v the heads have two identical pins, so can be reversed for centre -ve or +ve

    --- SoupGate-Win32 v1.05
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  • From GB@21:1/5 to Mike Halmarack on Sat Dec 7 20:08:58 2024
    On 07/12/2024 15:31, Mike Halmarack wrote:
    On Sat, 7 Dec 2024 11:44:39 +0000, Andy Burns <usenet@andyburns.uk>
    wrote:

    Mike Halmarack wrote:

    I was cautioned to ensure the polarity of a
    device's supply, indicating that these tend to vary.
    On enquiry to the variable power supply provider I was told that "all
    the interchangeable heads are positive"

    The generic wall-wart I have, is switchable 3/6/9/12v the heads have two
    identical pins, so can be reversed for centre -ve or +ve

    I wish.

    Send it back. Buy another.

    --- SoupGate-Win32 v1.05
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  • From Theo@21:1/5 to Mike Halmarack on Sat Dec 7 22:51:22 2024
    Mike Halmarack <mikehalmarack@gmail.com> wrote:
    My router power supply died. I got a new one. I also got an adjustable voltage power supply with 34 interchangeable heads from eBay, to avoid delivery waiting times in case of future power losses.

    Reading up on the subject, I was cautioned to ensure the polarity of a device's supply, indicating that these tend to vary.
    On enquiry to the variable power supply provider I was told that "all
    the interchangeable heads are positive" which I don't think is a very helpful answer.

    There appears to be no facility to ensure the polarity of each head
    without test equipment. This, nor change the polarity of the heads by
    any means.
    Is this because a negative inner is too rare to provide for?

    I think centre-positive is most common nowadays. But apparently Sony stuff (radios etc) all used centre-negative, and I blew something up because I
    used a cable lying around that had been wired centre-negative for testing a Sony thing.

    Theo

    --- SoupGate-Win32 v1.05
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  • From fred@21:1/5 to Mike Halmarack on Mon Dec 9 12:17:09 2024
    Mike Halmarack <mikehalmarack@gmail.com> wrote in news:oi68ljthg25ijb1bp788n7tmtiq05fcfeh@4ax.com:

    My router power supply died. I got a new one. I also got an adjustable voltage power supply with 34 interchangeable heads from eBay, to avoid delivery waiting times in case of future power losses.


    I'd expect the polarity to be identified by a symbol such as this beside
    the power input.

    https://ibb.co/28ZWSF5

    --- SoupGate-Win32 v1.05
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  • From fred@21:1/5 to Mike Halmarack on Tue Dec 10 17:14:50 2024
    Mike Halmarack <mikehalmarack@gmail.com> wrote in news:2ivflj179bshvgth41r1hh3e43k5glvft4@4ax.com:

    On Mon, 09 Dec 2024 12:17:09 GMT, fred <not@for.mail> wrote:

    Mike Halmarack <mikehalmarack@gmail.com> wrote in >>news:oi68ljthg25ijb1bp788n7tmtiq05fcfeh@4ax.com:

    My router power supply died. I got a new one. I also got an
    adjustable
    voltage power supply with 34 interchangeable heads from eBay, to
    avoid
    delivery waiting times in case of future power losses.


    I'd expect the polarity to be identified by a symbol such as this
    beside
    the power input.

    https://ibb.co/28ZWSF5

    That's the perfect illustration Fred. My confusion is more to do with
    the polarity of the output from the "Universal" power supply and the
    ability to change this if necessary.

    I should have added that I have yet to come across a supply of this sort
    that does not have centre positive and I would certainly expect a
    'universal' replacement to be centre pos if of fixed polarity. As others
    have mentioned some do come with a non polarised bi-pin connector so that
    the polarity can be reversed if required (and glued in place to avoid
    possible future error if easily disconected). Otherwise it will be a 'cut
    & shut' operation, neatest when soldered on a staggered cut and insulated
    with heatshrink sleeving.

    As you're on uk.d-i-y too I expect you will already have a multimeter :-)
    , if not you can get a cheapie for about a tenner to check polarities
    before risking connection.

    --- SoupGate-Win32 v1.05
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  • From jkn@21:1/5 to Mike Halmarack on Tue Dec 10 22:27:20 2024
    On 10/12/2024 08:42, Mike Halmarack wrote:
    On Mon, 09 Dec 2024 12:17:09 GMT, fred <not@for.mail> wrote:

    Mike Halmarack <mikehalmarack@gmail.com> wrote in
    news:oi68ljthg25ijb1bp788n7tmtiq05fcfeh@4ax.com:

    My router power supply died. I got a new one. I also got an adjustable
    voltage power supply with 34 interchangeable heads from eBay, to avoid
    delivery waiting times in case of future power losses.


    I'd expect the polarity to be identified by a symbol such as this beside
    the power input.

    https://ibb.co/28ZWSF5

    That's the perfect illustration Fred. My confusion is more to do with
    the polarity of the output from the "Universal" power supply and the
    ability to change this if necessary.


    most of the (cheap) 'reversible' wall-wart type adapters I have seen,
    with some sort of two-pin connector near the interchangeable heads,
    have *tiny* '+' and '-' symbols moulded into the heads and the power
    lead connector. Once you have spotted this, with a bit of thinking you
    can work out which way is which.

    I have had to make a couple of centre negative adapters recently. I
    don't trust those cheap interchangeable types and so take a
    centre-positive one, splice the cable and make it fit for purpose. I
    then take care to label it for clarity.

    I'd estimate that fewer than 5% are centre negative. I ones I made up
    were for audio purposes - a small Roland Guitar amp and a Casio
    sequencer. My Brother Label Maker is also centre -ve, "7 volts" IIRC.

    J^n

    --- SoupGate-Win32 v1.05
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  • From Abandoned Trolley@21:1/5 to Mike Halmarack on Wed Dec 11 11:05:47 2024
    On 07/12/2024 10:09, Mike Halmarack wrote:
    My router power supply died. I got a new one. I also got an adjustable voltage power supply with 34 interchangeable heads from eBay, to avoid delivery waiting times in case of future power losses.

    Reading up on the subject, I was cautioned to ensure the polarity of a device's supply, indicating that these tend to vary.
    On enquiry to the variable power supply provider I was told that "all
    the interchangeable heads are positive" which I don't think is a very helpful answer.

    There appears to be no facility to ensure the polarity of each head
    without test equipment. This, nor change the polarity of the heads by
    any means.
    Is this because a negative inner is too rare to provide for?

    rare, but they do exist.


    I have a chunky (1.2 amp) wall wart which came with a DLink router some
    time ago - the output is AC only !

    Its got a "normal" connector which is alarmingly compatible with the
    later DLink models, and about a million other things.

    Who needs smoke detectors ?

    --- SoupGate-Win32 v1.05
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