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D-SUB Connector puzzle

Hey guys,

this is a rather academic question because a few tens of microns don't matter much with those old clunkers, but still this got me puzzled:

Looking at datasheets of D-SUB Connectores from different manufacturers, I find three different inter-pin distances along the rows:

ERNI: 2.75mm Harting: 2.74mm for 9 and 15 pin connectors, 2.76 for the others. Deltron: 2.74mm FCT: 2.74mm

The inter-row distance seems to be consistently 2.84mm.

All of course are supposed to be according to the same DIN/ISO standard. Then there is the "US" and the "European" footprint, but I think the difference is the distance between the PCB holes and the front panel plane for the angled connectors.

I wonder if it is really true that the 9/15 pin plugs have an ever-so-slightly different pitch than the others. Who comes up with ideas like that?

robert

Reply to
Robert Latest
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Could it be that the original D type was in imperial inches, rather than metric, and there are rounding errors?

martin

Reply to
martin griffith

I got the impression they designed the outer dimensions first and then just divided by the number of pins minus one to get the exact pitch, but I could be wrong about that... Originally they were cable connectors and most users wouldn't have known or cared much about the exact pitch.

Best regards, Spehro Pefhany

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Reply to
Spehro Pefhany

I always understood that the 25 way connector was designed to have a distance of 1.3 inches between the centres of the end pins on the 13 way side thereby giving a spacing of 0.1083(recurring)inches or approx

2.75mm.

I have seen it surmised that the original specifier(s)/committee made a boo boo by making the original end to end measurement 1.3 inches (for 13 pins) instead of 1.2 inches, which would have a made it a nice

0.1inch spacing.

Alan

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Reply to
Alan

More likely it was in US inches.

Best regards, Spehro Pefhany

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Reply to
Spehro Pefhany

"Spehro Pefhany" schreef in bericht news: snipped-for-privacy@4ax.com...

2.75mm ~ 13/120 inch. Strange choice.

The russians made/copied many TTL 74xx chips, with partnumbers like K155. I was surprised when I discovered these have a pitch of

2.5mm, not 2.54mm. You can still squeeze them in 2.54 sockets, but with a 24 pin dip it really starts to hurt. 
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Thanks, Frank.
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Reply to
Frank Bemelman

For years I have worked with the D-Sub type connectors. The pin to pin spacing in the rows has typically been 0.109 inches. That said the mechanical drawings for the D-Subs from Amphenol (one of the original manufacturers for D_Subs along with ITT Cannon) show that the pin to pin center spacing for shell sizes E and A are 0.108 inches and are

0.109 for shell sizes B, C, and D. The row to row spacing has always been 0.112 inches. Any other dimensional info you will see in the mm realm is typically round-off error.

Many of the mechanical drawings I have referenced for D-Sub connectors from manufacturers do not specify the total dimension between the outside pins of the long row of pins. The prints are drawn in an manner where the center to center of the jack screw holes are specified. The connector pin pattern is then dimensioned to be centered either way from the center of the jack screw to jack screw holes.

- mkaras

Reply to
mkaras

European IC makers used a 'standard' pitch of 2.52 mm for quite a while, to accomodate both 2.50 and 2.54 mm. Their intention was presumably to eventually replace 2.54 with 2.50.

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Regards,

Adrian Jansen           adrianjansen at internode dot on dot net
Design Engineer         J & K Micro Systems
Microcomputer solutions for industrial control
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Reply to
Adrian Jansen

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