2.5 vs 3.5 jack and some other considerations

Dr. H. Nikolaus Schaller hns at goldelico.com
Thu Feb 17 10:12:05 CET 2011


Am 17.02.2011 um 09:28 schrieb Dmitry Shalnoff:

> On 16/02/11 23:28, David Lanzendörfer wrote:
>>> Hi list,
>> Hello list-user :-)
>> 
>>> is anybody here from GTA04 developers?
>> yes
>> 
>>> if it's not late, would be great to hear some case concerning 2.5 jack
>>> retention. That's only thing I found objectionable in the current tech.
>>> specification. is it possible to change it in final PCB version to 3.5 standard socket to make it compatible with most widespread headphones standard?
>> Well, I'm plagued by the same issue. Here where I live, all connectors are
>> Ø3.5mm while the FreeRunner has Ø2.5mm.
>> I talked with Nikolaus about this topic already, and it's not that easy.
>> The board wouldn't fit into the case anymore,
> 
> that understandable reason, but ... I see simple compromise, which is, to my mind, quite suitable for device audience and relevant to the spirit of the project... this is not a big difference with 2.5 and 3.5 socket pads. why not make just a bit wider pads under the socket to give a possibility to solder other jack for the people who would like to do that and ready to drill case hole to make it wider.
> 
> If I don't mistake ther is enough space over the socket in the case and even if not, the case easly can be modified by little filing.

Unfortunately there isn't either space over the jack
(there is the loudspeaker box). Nor on the PCB to
add placeholder pads to mount different connectors.

And since we found that there are thousands of
adaptors available we did choose this compromise
(although our design goal is "no compromises").

> at least (even if it stay in current status), what would be good to take into account this is the order of pins in the socket. Current GTA02 jack have non standard punout where is a 3 contacts jack just short one channel and to get normal stereo you need to get 4 contact jack and 3 pins socket and resolder it by youself (that what I did, for example)

We did change the pin order so that is compatible
(just from pin assignment not from size) to e.g.:

* Sharp Zaurus SL860
* iPod
* iPhone 2G
* 2.5mm AV-Chinch cables (white, red, yellow)

> 
> this adapter (which has similar order of contacts on the both sides) didn't work http://www.dealextreme.com/p/2-5mm-male-to-3-5mm-female-adapter-cable-white-14-5cm-23191

The link appears to be dead but I think that adapter
should work with the new pin assignment.

> so you would have need for a new one too...
>> Good thing is, that we also are already planning the gta05, and there I'm
>> organizing an amazing, cool and totally innovative new chassis in addition.
>> Can't tell too much as long as the specs are not CC-License, but:
>> It's TOTALLY cool ;-D
> 
> Heh :) that's sounds promising. would you like to make it public on early stage? it's open hardware project. let people to get involved.
> 
> Just one last think... it's about the case and screen size. I totally like current form-factor and, as designer, I found it very interesting and relevant to the idea of the project. I really like that hole and that's difference from hundreds of other mass-market pocket bricks. But the big minus of the current case that a limitation of the screen size. Probably, would be great to focus on form-factor "flexibility" and modularity of the hardware (as I suspect, you, probably, already planning something in this way).
> 
> Ideally that could be really great to have a chance to repack all hardware in selfmade case with _other_screen_ and other set of peripheral devices. (is LCD have a standard interface?) It would gives dramatically new abilities for individuals and small design companies to create customised portable devices.

Unfortunately no. Every LCD module is different in
mechanics (border around the visible frame, thickness,
connector position, connector size) and electronics
(different voltage levels, control signals, data protocol,
etc.). Therefore you have to firstly choose a display and
then secondly design a case for it. And thirdly design
a PCB. No chance to do it the other way round.

What the GTA04A3 will have are two B2B connectors
where the most important LCD signals are available.
So it can be mounted onto a second adapter board
which carries a different (larger) LCD and all the glue
logic. This makes the whole design thicker by approx.
3mm (2mm for connector + 1mm for second PCB).

> anyway, thank you guys that you continue the project. I reckon that it's just a beginning of the big movement which eventually changes our understanding of the market and design of things.

Yes, that is the reason why we started to work on it.

And if we look around the current "ecosystem" discussions,
the need for a open source friendly, flexible and well
documented hardware becomes even more urgent.

BR,
Nikolaus

== Making FLOSS friendly HW for Independent People ==




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