3.5mm Stereo Connector

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nfk

Senior Member
Hi,

This may be a question for Technical but regarding the standard PICAXE programming connector (the stereo 3.5mm plug) does anyone know why the tip is ground rather than the ring nearest plastic moulding?

On nearly everything else I can find that uses a stereo connector, the convention is against the PICAXE way of doing things.

Regards and Seasonal Greetings to all of you. :)

Nigel
 
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BeanieBots

Moderator
They were the cheapest (ex camera) leads they could find at the time.
This has actually come up a few times before. It is a bit of an odd way to wire it!
 
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ddee

New Member
The PicAxe use of the tip as a ground seemed odd to me too. However, in researching the early days of telephones, I discovered that the tip as ground was the convention. The wikipedia article on tip and ring (http://en.wikipedia.org/wiki/Tip_and_ring) states why fairly clearly:

"While the ring is connected to -48 volts, the tip is connected to ground for safety. This is because when the telephone operator is handling the plug, the tip is more likely to touch something other than intended. With the tip as ground, nothing dangerous will happen."
 
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Andrew Cowan

Senior Member
Makes sense, unless the body of the plug is connected to the connector nearest to the body.

This is why most plugs use that one a negative.
 
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westaust55

Moderator
Truth in what ddee says.

The old manual exchanges had the leads with the plugs coming out of the rear top of a desk/shelf like part of the station and the sockets were in a vertical face at the back. Hence when a lead was not connected, all the tip were upmost.
 
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inglewoodpete

Senior Member
ddee is correct but I won't be using a -48volt exchange battery on a PICAXE or a my camera ;)

As an aside, don't go plugging the 3.5mm programming plug into your PC's sound card output as my kids did a couple of years ago....
 
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inglewoodpete

Senior Member
I didn't actually witness the event. There is no obvious physical damage to the sound chips etc (the sound was integrated on the motherboard).

The sound output and input functions 'ceased to be' - to quote a famous comedian.

The motherboard had a spare PCI slot so was able to use a cheap add-on sound card.
 
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gibbman

New Member
Back in the day, I worked in a satellite communications station, and it was a late watch prank to drop a patch cord bearing 60 mils high level TTY traffic down another watchstanders pants. Low level TTY ruined the prank, now I'm sure there's no TTY at all in the old station.
 
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leftyretro

New Member
gibbman said:
Back in the day, I worked in a satellite communications station, and it was a late watch prank to drop a patch cord bearing 60 mils high level TTY traffic down another watchstanders pants. Low level TTY ruined the prank, now I'm sure there's no TTY at all in the old station.
Click to expand...
Ah yes, 5 by 5, RYRYRYRYRY, the quick brown fox ran over the lazy dogs...

Remember the Christmas art that would flow through the traffic channels this time of year?

Lefty
 
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