That is just about what I am thinking of. I just worry that the loud
speaker announcing please return to the store and the flashing lights
might scare the cat! Just kidding of course. Wire loop and a small cap for
the cat. Then the sweeping oscillator for the door. Now I need to find the
circuit diagram. The other simple way to do it would be to build a metal
detector and put a couple of nuts in each bowl of cat food! I think that
would work better with a dog though. Yes yes just kidding again. We were
up wrapping presents all last night so I could mail them today. It is
rought when you don't get the gift list for the grandchildren till 3 days
ago!
Tim Laing
>
> If you want to do something simpler, you could try a passive resonance
> absorber - this is how some of those anti theft things in shops work -
> have an oscillator sweeping a small frequency range - the tag on the cat
> is a resonant LC circuit. When it is near the search coil, there is a dip
> in te spectrum - basically the same idea as a grid dip meter. This might
> be more sensitive than just a shorted loop. The oscillator sweep will give
> immunity to random objects - something like a shorted loop will absorb
> across the whole range - the sweep is wide enough that thermal variations
> etc in the resonant circuit are accounted for - youare just looking for an
> absorption dip anywhere in the range. Shop sensors typically do this in
> the 6-8mhz range.
> Dan
>
>>
>> I work with RFID tags at work all the time, I hate those little buggers,
>> half the time they don't want to read on the pallets. Knowing the
>> typical
>> cat I will have to be replacing them all the time. I think if I can get
>> a
>> simple circuit to detect a shorted loop about 1.5-2 inches in diameter I
>> will be pretty well set. I just want to throw something together with
>> parts I have on hand. The RFID is a good idea though, thank you for
>> suggesting it.
>> Tim Laing
>> >
>> > get an RFID reader. some RFID dev boards can be had for pretty cheap.
>> Put
>> > the tag on the cat, door opens for the cat with the tag...
>> > Dan
>> >
>> >>
>> >> Hi, this is off topic but I know there are a lot of electronics guys
>> >> here.
>> >> I posted this on Neonixie-L first. I also thought I would post here
>> as
>> >> well. This cat door is for the black cat that was guarding my CRA
>> >> skysweeper tube! I guess a automatic cat door would be on topic if I
>> >> used
>> >> tubes. The tubes could sit under his cat bed and keep him warm. But I
>> >> think that transistors or an IC or two would be more practical.
>> Thanks
>> >> guys.
>> >> Tim Laing
>> >>
>> >> ---------------------------- Original Message
>> >> ----------------------------
>> >> Subject: Off topic Circuit for automatic cat door.
>> >> From: [email protected]
>> >> Date: Thu, December 20, 2012 3:04 am
>> >> To: [email protected]
>> >> Cc: [email protected]
>> >> --------------------------------------------------------------------------
>> >>
>> >> There are a lot of smart people on this group so I thought I would
>> ask
>> >> for
>> >> some help. We have a stray cat that we have adopted. He is an indoor
>> >> outdoor type of cat. My personal experience is if they started
>> outdoors
>> >> they are very unhappy if you try to keep them in all the time. Well
>> the
>> >> problem is there are some other strays that beat up on him and get at
>> >> his
>> >> food. My temporary solution was to leave the window to our stair
>> landing
>> >> open and Skink could jump up about 5 feet and get in through the
>> window.
>> >> Then he could sleep on the landing if we were not home and eat as
>> well.
>> >> Well we have two problems, 1) it is now pretty cold(The stairs lead
>> to
>> >> our
>> >> front door so that area is not heated.) 2) The big problem is I came
>> in
>> >> tonight and the wild stray that has been going after Skink had him
>> >> cornered on the landing. Needless to say I wasn't too happy, the last
>> >> thing I need is a tom spraying on the landing! And no, I am not
>> going
>> >> to
>> >> shoot the other cat as I live in town and I don't shoot cats etc.
>> >> My idea was to make a automatic cat door that would open for only
>> one
>> >> cat. I was thinking that if I made a cat collar out of light gauge
>> >> copper wire with male and female spade connectors this would form a
>> >> single turn shorted loop. (The wire would be light gauge so if he got
>> >> caught the wire would break.) The cat door would be a partly formed
>> with
>> >> a square wood tube that the cat would enter with a solinoid latched
>> door
>> >> at one end. On the outside of the wood cat tunnel I would wind some
>> >> turns of copper wire that would be tied into an oscillator circuit.
>> The
>> >> shorted turn would either kill the oscillator or shift its frequency
>> >> allowing the door to open.
>> >> I can build just about anything electronic or mechanical and have
>> lots
>> >> of parts on hand but I am not very skilled on scratch designed
>> circuits
>> >> like this. Would somebody here be willing to help me with some
>> pointers.
>> >> I can work from an hand drawn schematic. I should be able to supply
>> >> power from a wall wort if needed.
>> >> Thanks
>> >> Tim Laing
>> >>
>> >>
>> >>
>> >>
>> >>
>> >> ------------------------------------
>> >>
>> >> Visit the TCA web page at: http://www.tubecollectors.org
>> >>
>> >> If you have questions about or problems with
>> >> the TCA reflector, please contact the list manager
>> >> Ron Lawrence directly at W4RON at carolina dot rr dot com
>> >>
>> >> Visit the TCA Tube Photo Gallery web page at:
>> >> http://radioheaven.homestead.com/TCA.html
>> >>
>> >>
>> >>
>> >> Yahoo! Groups Links
>> >>
>> >>
>> >>
>> >
>>
>>
>>
>>
>> ------------------------------------
>>
>> Visit the TCA web page at: http://www.tubecollectors.org
>>
>> If you have questions about or problems with
>> the TCA reflector, please contact the list manager
>> Ron Lawrence directly at W4RON at carolina dot rr dot com
>>
>> Visit the TCA Tube Photo Gallery web page at:
>> http://radioheaven.homestead.com/TCA.html
>>
>>
>>
>> Yahoo! Groups Links
>>
>>
>>
>
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