Hello, well the cat problem has escalated. I opened the door this morning
and there was a unfamiliar tom on the stairs who had our cat backed up by
the window so he couldn't get to his accustomed cat bed. I caused some
consternation on the part of the 2 cats, finally after some growling the
tom bailed out the window which I promptly closed. This is the second time
that I have seen the tom on the stairs and some things on the landing got
broken.
One of the guys on Neonixie-l pointed out some cat doors that work with
a collar. Due to the situation with our cat and me having to spray
Fabreze on the landing for the smell. I went and ordered a cat door
that was pointed out to me on E-bay, it works with a special collar. So
till that comes we will have to work out something with the cat on
going in and out. Skink the cat is going to the vets for a neutering
on the 9th of January, I will get him chipped at the same time and then
I may look to upgrade the door. Chip operated doors run well over $100
though.
So I want to thank everybody for the ideas and the links to the door. I
havn't had a cat that we let inside for well over 10 years so I havn't
kept up on any of the doors etc for cats. All your ideas were a help
and I appreciate them very much.
Happy holidays to everybody!
Tim Laing
> Simple receiver tuned to harmonic would be easy.
>
> danial stocks wrote:
>
>>
>>
>> Yep the nonlinear junction detector is another interesting approach. I
>> think the harmonic generation is possibly a less easy thing to detect
>> than an on frequency passive resonator, although the harmonic method
>> is also used in a number of systems.
>> Dan
>>
>> >
>> > > I don't think anyone has suggested a simple 'tag' which consists
>> of just
>> > > a coil with a diode in series. Could be a loop with detector, such
>> as
>> > > some of the cheapest RFID tags use. The interrogator is something
>> > > driving a large coil [in this case just around the openint] and
>> > > detecting the second harmonic generated by current flowing in the
>> > > diode. I think it could be very simple but not proposing a design.
>> > >
>> > > Ed
>> > >
>> > > danial stocks wrote:
>> > >
>> > >>
>> > >>
>> > >> 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: lai...@wcoil.com
>> > >> > >> Date: Thu, December 20, 2012 3:04 am
>> > >> > >> To: neonixie-l@googlegroups.com
>> > >> > >> Cc: lai...@wcoil.com
>> > >> > >>
>> > >>
>> --------------------------------------------------------------------------
>> > >> > >>
>> > >> > >> 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
>> > >> >
>> > >> >
>> > >> >
>> > >>
>> > >
>> > >
>> >
>> >
>> >
>> >
>> > ------------------------------------
>> >
>> > 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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