Hi Dwayne, I've had a Sureflap microchip cat door for just about two years and it works great over 99% of the time. Occasionally if it is really filthy it won't always lock but other than that it's been fine. And it's really frugal, I'm only on the second set of 4-AA batteries. It has a manual catch if you want to lock it completely, normally it's open for all exits but only those "on the list" for entry. It is a bit smaller in height than most doors but my neighbor has one and her 22 pound cat fits through OK. Just make sure you don't put it too high or low in the wall/window/door. The bad news is it's over $100 and your cat also has to get a microchip but it really makes life simple. It's well made and doesn't flood the house with water even if the rain has a lot of wind behind it. Best regards, Bob On Mon, Dec 9, 2013, at 09:53 PM, Dwayne Reid wrote: > Good day to all. >=20 > I have a 4-year-old cat who discovered this past summer that he=20 > *really* liked being outdoors. He was strictly an indoor cat up=20 > until that time but now he gets cranky if he's not allowed outside. >=20 > That wasn't a problem during the summer months - and not even that=20 > much problem during the fall. He spent literally weeks outside and=20 > the only time that I saw him was when I called him every evening to=20 > come get supper (when it got dark). >=20 > But now its winter outside and he is spending his days inside. We've=20 > got a foot or more of snow and the temperature plummeted down to -30C=20 > or so this past week. He won't be a happy camper if he has to stay=20 > outside for extended periods. >=20 > So, several weeks ago, I installed a cat door in my bedroom=20 > window. It took him a while to figure out how to get outside but he=20 > sure had no problem figuring out how to come back inside . Now=20 > he comes and goes as he pleases. >=20 > I knew that it would only be a matter of time before some of his=20 > neighborhood feline friends also discovered this wonderful door into=20 > warmth, fresh water, and food. It happened today. >=20 > So now I've locked the cat door into allowing traffic from IN to OUT=20 > only. I have to let the cat in manually when he wants in. That's OK=20 > when I'm here but not good during the day when I'm at work. >=20 > I want to put a small, short-range transmitter on his collar so that=20 > I can have a pair of RC servos un-block the 'IN' traffic=20 > direction. I thought about using permanent magnets on his collar,=20 > but am unhappy with the prospect of them gathering ferrous debris as=20 > well as the very short range operation. I think that RF is my best=20 > bet. Modulated IR would be a close second choice. >=20 > Is anyone aware of an inexpensive, short-range RF link that has a=20 > transmitter that will operate for several months from a single=20 > battery change? It really only needs a foot or so of range. I don't=20 > really care how large the receiver is but the transmitter would=20 > ideally be in a waterproof enclosure that is suitable for attaching=20 > to collar for a small cat. >=20 > I'd rather purchase a ready-made transmitter if possible (and=20 > matching receiver). Is anyone aware of something that might be suitable? >=20 > Many thanks! >=20 > dwayne --=20 http://www.fastmail.fm - Choose from over 50 domains or use your own --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .