This has been a fine week for the pet door. We actually have a fully functional prototype! The door itself is constructed of a high-tech polymer which is easy to work with and provided a quick means of prototyping the door mechanism. (Read: Legos) The door has the two wayoperation desired, with the ability to select one-way operation.
Click here to download the full size of the above Circuit.
It has a sensor to determine if the pet is still in the door before it is closed. This also will reopen the door if something gets in the way while it is closing. The sensor used to monitor the door opening is an infrared beam which is in the plane of the door. This means that the door will never strike the pet. A contact sensor would also be beneficial just to make sure everything is okay, however. In order to get the sensor installed as soon as possible it is just powered by a basic DC voltage. The problem with this is that the ambient lighting has an affect on sensor performance and can cause false alarms. To get around this the IR should be modulated at a frequency of around 10 kHz. This frequency would prevent any cross-talk with the main IR system which is running at 40 kHz. It is yet to be seen if we will have enough time to implement this extra circuitry. Since it is functional as is, we probably won`t bother with it. Something else that could be done is to try to reduce the bulk of the pet`s collar device. The primary thing is to find a suitable battery which is compact and will still give reasonable endurance. One battery that looks promising is the 6 volt Lithium type used in many cameras. It then could be packaged appropriately. We are making good use of the Motorola controller. Our system in its current configuration has four inputs and seven outputs, all simple logic signals (0 or 1). We are looking forward to...
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