Anelok: memory card eject direction

Felix sucotronic at gmail.com
Mon May 19 01:27:33 EDT 2014


That remember me of the Wikireader micro sd card location, also behind  the
AAA batteries:
http://s4.postimg.org/3tpc9r7t9/wikireader_microsd_maxwidth.jpg

As you mentioned, I see the two main problems as the battery holder wearing
and the RTC time loss. Perhaps a battery holder with a screw would solve
the wearing, but for the RTC (which I think is important in this device) I
don't see a easy solution.


On Sun, May 18, 2014 at 5:27 PM, Werner Almesberger
<werner at almesberger.net>wrote:

> The first prototype of Anelok ejected the memory card towards the
> upper long side of the device, towards the inside of the sidewall.
> To remove the card, one had to open the case. This is intended as
> a protection against accidental card ejection.
>
> For the next version, I'm toying with the idea of ejecting the
> card into the battery compartment.
>
> Here is what this would look like:
>
> - card fully inserted, battery present:
>
> http://downloads.qi-hardware.com/people/werner/anelok/tmp/batcard-inserted.jpg
>
> - card released by holder but not yet pulled out:
>
> http://downloads.qi-hardware.com/people/werner/anelok/tmp/batcard-released.jpg
>
> - most of the card pulled out:
>
> http://downloads.qi-hardware.com/people/werner/anelok/tmp/batcard-pulled.jpg
>
>   I put the card holder on a ~4 mm support so that the card could
>   clear the bottom battery contact. That's why the pads of the
>   holder look out of alignment.
>
> - as above, but seen from an angle:
>
> http://downloads.qi-hardware.com/people/werner/anelok/tmp/batcard-angle.jpg
>
> Pro:
>
> - presence of battery adds extra protection against accidental
>   ejection, e.g., after a drop that opens the case,
>
> - slows down potential "card snatchers",
>
> - reduces area of case that needs to be opened regularly, thus
>
>   - the rest of the case can be permanently closed, better
>     protecting the main circuit, and
>
>   - the battery compartment can get a small door, without the need
>     to disassemble large portions of the device.
>
> Contra:
>
> - more work to change the memory card,
>
> - memory card extraction takes more time (if you're in a hurry),
>
> - battery removal to change memory card increases wear on battery
>   connector (*),
>
> - prolonged battery removal may lead to loss of backup power and
>   thus of timekeeping (it's okay to lose RAM content).
>
> (*) it seems that it may not be as sturdy as I hoped it would be.
>     More about this in the next mail.
>
> Opinions ?
>
> - Werner
>
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-- 
Felix
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