Author Topic: Breakway header with strange pitch  (Read 619 times)

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Offline 17_29bis

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Breakway header with strange pitch
« on: November 09, 2018, 07:01:21 pm »
Hello,

I am trying to repair a 1 mile car alarm remote that consists of 2 boards -  logic  and RF (CC1020 based) one. I need to make a adapter for easy swapping of RF boards (borrowed the second RF board and should returned it later) but the original connector seems to have an usual pitch  - 1.1 mm - this type of connectors is not available from DigiKey and other reputable online sources, they offer only 1 and 1.2 mm pitch connectors.
So, what I am dealing with?   An unusual connector or wrong pitch measurement (meaning that I am looking at 1 mm pitch header)?
 
Thanks!
 

Online Ian.M

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Re: Breakway header with strange pitch
« Reply #1 on: November 09, 2018, 08:12:26 pm »
The vernier caliper reading looks like 5.4mm measured across the outside of  five pins.  However that has one more pin width in it than 5x the pitch.  If you measure the thickness of one pin I'd bet it will be about 0.4mm, so after subtracting that you'll have 5mm for 5 pins so the connector is 1mm pitch.
 

Offline 17_29bis

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Re: Breakway header with strange pitch
« Reply #2 on: November 13, 2018, 04:59:53 am »
The vernier caliper reading looks like 5.4mm measured across the outside of  five pins.  However that has one more pin width in it than 5x the pitch.  If you measure the thickness of one pin I'd bet it will be about 0.4mm, so after subtracting that you'll have 5mm for 5 pins so the connector is 1mm pitch.

Unfortunately that does not seem to be true. I ordered 1mm pitch male/female headers and they are too small as shown on the following picture. So, 1.2mm pitch is too big, 1mm pitch is too small. How could it be?

 

Offline Habropoda

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Re: Breakway header with strange pitch
« Reply #3 on: November 13, 2018, 06:03:27 am »
There are four gaps, not five; so subtract one pin width and divide by four.  Fudge in a possible pebcavc error and it's probably the common 1.27mm (.05 inch) header.  Lots on Digikey and elsewhere.
« Last Edit: November 13, 2018, 06:15:51 am by Habropoda »
 

Online Ian.M

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Re: Breakway header with strange pitch
« Reply #4 on: November 13, 2018, 09:54:08 am »
Whoops - I committed a classic fencepost error.  :palm:  :-[

1.27mm (0.05") is very plausible - I doubt plastic vernier calipers are accurate enough to distinguish that from 1.25mm pitch over a short connector*.   Its easy enough to check - you must have something that's 2.54mm (0.1") pitch you can compare with, (e.g. a new DIP IC) and under a good magnifier, the middle and outer pins of your 5 in connector should line up exactly.

* Even if its is 1.25mm pitch I doubt it  will matter over five pins due to the hole tolerances. e.g. 2.5mm pitch ICs as produced by the USSR semiconductor industry were only incompatible with the western 2.54mm (0.1") pitch ones in higher pin counts like memory chips and CPUs
 

Offline tkamiya

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Re: Breakway header with strange pitch
« Reply #5 on: November 13, 2018, 03:44:59 pm »
Japanese makers also used metric version.  I've seen 2mm and 2.5mm pitch.  This was in 80s.  It wouldn't surprise me if there are half pitch of those.
 


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