On 09/10/2015 11:02 PM, Me wrote:
snip

21st century problems...
Connector problems that annoy the crap out of me date back to the 19th
and 20th century - and should have been replaced long ago:

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The 19th century 1/4" phono plug, and subsequent 3.5 and 2.5mm miniature
versions. Quick and easy on a telephone switchboard back in the 1800s,
an abomination ever since, especially on mobile devices.
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The 20th century 12v auto "cigarette lighter/accessory socket". Surely
car-makers could have agreed on some alternative standard 1/2 century ago.

The 20th century "coaxial/barrel" DC power connector, usually on
wall-wart power supply/charger. Not only comes in a zillion different
sizes of external barrel diameter and internal hole size, but to top it
off, adapters with the same voltage and identical plug size can come
with reversed polarity.


Just to be pedantic, and because I spent many years in broadcast
engineering:
In the **starred** paragraph above, the plug commonly used for
headphones is a "phone" plug, not a "phono" plug.
The "phone" plug came into use just as you say: from the telephone
switchboard. The connections on the plug are tip, ring, and sleeve. Tip
and Ring are the electrical connections for the telephone conversation
path, the sleeve is a ground connection. To this day, telco lineman
refer to the red and green wires as tip and ring.
The "phono" plug or "RCA Phono" plug was originally used for
phonographs. It is small, inexpensive to make, and easy to install. The
plug's construction allowed it to make a good mechanical connection, and
if it worked loose, it could be adjusted tight with a common pliers!
Eventually this connector was used for most home audio devices: tape
decks, tuners, etc.

As for the coaxial/barrel DC power connector, not only does it come in a
zillion different combinations of O. D., I. D., and polarity, but it
comes in different lengths, and is not limited to DC. I say bring back
screw terminal barrier strips!

--
Ken Hart