Re: CBM edge connectors pitch?
On Thu, Oct 13, 2016 at 4:12 PM, jim stephens wrote: > If these are the connectors that can have keys inserted between every > connector, the small difference would be significant as those would not > align between a metric connector and an English (inch) board. The > electrical connections would line up w/o any keying as you say. Assuming you use the center as your reference point, on the maximum width (86-pin) connector, nothing is going to be off by more than 5.25 mils. That's not enough to cause a problem with keying.
Re: CBM edge connectors pitch?
On 10/13/2016 3:07 PM, Eric Smith wrote: It doesn't make much difference in practice. The highest pin-count .156" connector I've ever dealt with was 86 pin (43x2), and the difference in the nominal first-to-last position is only 10.5 mils, which is on the order of the non-cumulative position tolerance. If these are the connectors that can have keys inserted between every connector, the small difference would be significant as those would not align between a metric connector and an English (inch) board. The electrical connections would line up w/o any keying as you say.
Re: CBM edge connectors pitch?
On Thu, Oct 13, 2016 at 1:56 PM, Brent Hilpert wrote: > As Tony suggests, it matches up with 5/32" spacing, just as 0.125 is 1/8". > Where the rounding of the 1/4 thou (0.00025) took place - in the name or the > implementation - I'm not sure. Implementation. Years ago I verified with several vendors that the connectors really were engineered for 0.156" or 3.96mm, not 5/32" or 3.97mm. (I'm not 100% certain that was always true, but it was when I inquired.) It doesn't make much difference in practice. The highest pin-count .156" connector I've ever dealt with was 86 pin (43x2), and the difference in the nominal first-to-last position is only 10.5 mils, which is on the order of the non-cumulative position tolerance. I just happened to look at the drawing for a TE 2-530666-1 connector, and they specified the pitch in one place as 0.156/3.96 (in/mm), and in another place in the same drawing as 0.156/3.175. Oops!
Re: CBM edge connectors pitch?
On 2016-Oct-13, at 10:39 AM, Jim Brain wrote: > I thought the question about the prevalence of .156" connectors in early > systems was interesting and I assume someone here has the detail on the > rationale. > > Jim > > Forwarded Message > Subject: CBM edge connectors pitch? > Date: Thu, 13 Oct 2016 19:31:47 +0200 > From: silve...@wfmh.org.pl > Reply-To: cbm-hack...@musoftware.de > To: cbm-hack...@musoftware.de > > Do we know what is the norm used in the CBM edge connectors? Like the IEEE, > USER PORT or CASSETTE? > > I found out mentions that it uses a 0.156" pitch. Where the heck does that > come from? Nothing "round" in either metric or imperial.. > -- > SD! > Message was sent through the cbm-hackers mailing list The 0.156" is presumably the oldest PCB edge connector, I have an example in tube equipment going back to 1959. Very common in all sorts of equipment through the 60s and 70s. As Tony suggests, it matches up with 5/32" spacing, just as 0.125 is 1/8". Where the rounding of the 1/4 thou (0.00025) took place - in the name or the implementation - I'm not sure.
RE: CBM edge connectors pitch?
> I thought the question about the prevalence of .156" connectors in early > systems was interesting and I assume someone here has the detail on the > rationale. I have wondered if it's an approximation to 0.15625" -- 5/32" pitch. -tony
