On Thu, 23 Jun 2011 23:54 +0100, "Oli Glaser"  wrote:

> On the cat door Bob - what exactly does it do and how? Does it ID the=20
> cat(s) or do you only have one?
> I'm asking because we are total "cat people" here (i.e. the cats own the=
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> house and are tolerating our presence)
> We already have an electric cat door purchased from a small L.A company,=
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> but I was thinking it would be nice to know things like which cat (we=20
> have 4) comes in/out and when, we have had a few situations where it=20
> would be useful to have that information.
> I'm thinking PIC with some wireless ethernet module to network, or cheap=
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> radio module at either end to USB. For the ID it could be RFID, IR,=20
> optical recognition, etc.
> It's just a "rainy day" project idea, that will be filed alongside the=20
> other hundred things I want to do when I have a spare minute, but any=20
> info on your project would be appreciated.

Hi Oli,
Just the one cat, sadly no longer on this plane. It takes about two
weeks to train a cat to open doors from the outside. There's a patch of
loop fastener fabric glued to the door, she has to grab it with her
claws and pull the door open a bit, here's a video:
http://bobblick.com/yumyum_hi.wmv
There's a PIC and a hobby servo on each door and a photocell that gets
polled when the door starts to open to figure out which side of the door
the cat is on. The doors plug into an extra wire pair in the house phone
wiring with a simple network protocol that talks to an interface on the
linux box that is my home fileserver and is always on.

I've built a lot of cat doors over the years and the pull-open style
outfoxes pretty much all critters, including other cats. YumYum had a
bad hip so in her later years I moved one of the doors(the one in the
video) from a window down to ground level and even then never had
intruder problems. But raccoons could be a problem because they are
strong. They probably wouldn't fit but if they tried they could break
the mechanism.

If I was doing it today I would probably use Sureflap doors, which can
be trained to trust each cat's implanted RFID microchip. And if I had
multiple cats I'd hack the door to get the RFID numbers to track each
one separately. The Sureflaps must have an awesome RFID circuit, they
run on 4 AA batteries for almost a year. Here's a link:
http://www.sureflap.co.uk/
You can get them in the UK and also the US. If you'd rather roll your
own, you can get 125KHz RFID readers at seeedstudio. The microchips in
disposable syringes are on Ebay or Amazon. I recommend the Bayer brand.
I wouldn't implant them myself, but here in the US there is no
standardization in pet RFID so the brand does matter and you might need
to bring the one you want to your veterinarian.

Cheerful regards,

Bob

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