[neonixie-l] Passive Resonance Re: [TCA] [Fwd: Off topic Circuit for automatic cat door.]
Here is a link for a (old)patent on a vehicle in lane detector using passive coils in the roadway. No circuit details but it sounds like what Dan was talking about. 12 inch single turn coils in the road with a 100nF cap in series. etc. The hard part of this project is figuring out what the search description should be. http://books.google.co.in/patents/US5708427 Tim Laing > 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
Re: [neonixie-l] Re: Off topic Circuit for automatic cat door.
Can't you just set the cat to download and install updates automatically? ;) Ray On 20 Dec 2012, at 21:20, Terry Kennedy wrote: > On Dec 20, 3:37 am, Ray Fenwick wrote: >> Just in case you didn't know, exactly this device has been built already and >> is commercially available. It uses the subcutaneously implanted RFID >> 'microchip' that is used worldwide for identifying animals, and will let in >> your cat(s) and only yours (you program which cat's to allow). >> >> They're great because they're fool proof, and do not rely on a collar that >> could be lost or pose a strangulation hazard to for the cat. > > They're also handy for cats that have never worn a collar and might > object to it. > > The only thing to watch out for is that there were several competing > microchip solutions not too long ago, and in the past someone reported > installing one of these cat flaps, being unable to get it to recognize > their cat's microchip, and the cat flap support people told them they > needed to take their cat in to be upgraded from a 16-digit to a 20- > digit chip! > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To post to this group, send an email to neonixie-l@googlegroups.com. > To unsubscribe from this group, send email to > neonixie-l+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/groups/opt_out. > > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
[neonixie-l] Re: Off topic Circuit for automatic cat door.
On Dec 20, 3:37 am, Ray Fenwick wrote: > Just in case you didn't know, exactly this device has been built already and > is commercially available. It uses the subcutaneously implanted RFID > 'microchip' that is used worldwide for identifying animals, and will let in > your cat(s) and only yours (you program which cat's to allow). > > They're great because they're fool proof, and do not rely on a collar that > could be lost or pose a strangulation hazard to for the cat. They're also handy for cats that have never worn a collar and might object to it. The only thing to watch out for is that there were several competing microchip solutions not too long ago, and in the past someone reported installing one of these cat flaps, being unable to get it to recognize their cat's microchip, and the cat flap support people told them they needed to take their cat in to be upgraded from a 16-digit to a 20- digit chip! -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
[neonixie-l] RE: [TCA] [Fwd: Off topic Circuit for automatic cat door.]
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: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 frequen
Re: [neonixie-l] Off topic Circuit for automatic cat door.
_http://www.ebay.com/itm/160942129905_ (http://www.ebay.com/itm/160942129905) $50 shipped That is the exact unit I use. 2 cats. Replace battery about once every 6 months. My cats in - all others out. Took the cats about a day to figure it out. Michail In a message dated 12/20/2012 12:04:14 A.M. Pacific Standard Time, lai...@wcoil.com writes: 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 -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
[neonixie-l] Re: Off topic Circuit for automatic cat door.
There are plenty of magnetic or RF collar products available designed for this purpose -- coupled with an actuated door flap. Do a little googling, you'll find something you can buy cheaply enough. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
Re: [neonixie-l] Off topic Circuit for automatic cat door.
> 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.
To get started, look for circuits for grid dip meters, theremins, or (best of
all) metal detectors.
You should be able to get a reliable frequency shift with a shorted-turn sort
of collar at
pretty much any reasonable frequency. I'm imagining about a 30-turn coil as
the sense
coil (that the cat walks through) resonating with a couple of capacitors in a
Colpitts
configuration (that avoids having to make a tapped coil).
Actually, thinking about it, I'd hang a resistor in the power supply to the
oscillator to
measure the current draw - when a shorted turn shows up, the oscillator should
draw
more power, creating a larger voltage drop across the sense resistor. A simple
RC
filter and or peak detector after that would let you use a simple comparator to
detect
the change (detecting a change in a DC level seems easier than detecting a
change
in frequency).
As Ray pointed out, RFID would work too, with a tag in the collar or the
in-the-body kind.
There are commercial versions of this, as well as RFID sensors available from
adafruit
and the like.
There was also a project that used a video camera and profile recognition to
let in a specific
cat - and only if the cat wasn't carrying an animal in its mouth! It's a
little over the top, but does
refer to a ready-made cat door ("Cat Mate") with a solenoid to unlock it, which
might be useful
if you don't want to build your own door mechanism.
http://www.quantumpicture.com/Flo_Control/flo_control.htm
- John
--
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RE: [neonixie-l] Off topic Circuit for automatic cat door.
Hi Tim Just in case you didn't know, exactly this device has been built already and is commercially available. It uses the subcutaneously implanted RFID 'microchip' that is used worldwide for identifying animals, and will let in your cat(s) and only yours (you program which cat's to allow). They're great because they're fool proof, and do not rely on a collar that could be lost or pose a strangulation hazard to for the cat. I understand you may rather build than buy an off-the-shelf product, but maybe it can give you a few pointers? Here's a sample listing (not affiliated etc.) http://tinyurl.com/ct6abq5 HTH Ray -Original Message- From: neonixie-l@googlegroups.com [mailto:neonixie-l@googlegroups.com] On Behalf Of lai...@wcoil.com Sent: 20 December 2012 08:04 To: neonixie-l@googlegroups.com Cc: lai...@wcoil.com Subject: [neonixie-l] Off topic Circuit for automatic cat door. 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 -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
[neonixie-l] Off topic Circuit for automatic cat door.
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 -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
