Thursday, August 16, 2007

Reliable precision vacation automatic dog feeder and waterer 2

With a little time, my feeder has improved a great deal. I found out by accident that corrugated cardboard box can be treated like wood. You can screw them, bolt them and nut them, glue them, tie them, and best of all, they comes in with most mail orders over the Internet.

Now the feeder is almost like my original simple vision. Find or make a box that is large enough to hold one meal. Use the side with the smallest dimension as the door. Drill two hold to mount the motor, using small bolts and nuts. My toy motor kit comes with a gear box that can mount a rotating arm. The arm is used to keep the door shut. When the motor rotates, the arm rotates away and opens the door for the dry food to drop down. You can drop down a tray of wet food too.

The rest you need is a 7 day timer to turn on the dc adaptor, which in turn drives the motor for a minute. For each day (or meal) you need three components, box with motor, dc adaptor and timer. They work independently so it's highly reliable. There's no single point of failure. And unlike commercial ones that uses a single "valve" to move the dog food, my design allows you to put whatever you want into the box precisely - medicine, treats for different days of the week.

I mount the boxes near the top of a large cardboard box, and tie the large box to garden furniture. There is no mess as the food will not drop outside of the large box, and the dog can't possibly move the box tied to something heavy.

There are plenty of automatic waterers, basically like the toilet tank that will automatically fill themselves and shut off when full. But the commercial ones are far too small, and far too expensive compared to the toilet flush valve.

I was looking to build something to mount a small float valve when I found something better. It was a float valve designed for cattle. I just mount it on a bucket with the supplied hardware and attach a garden hose to it. The large volume in the bucket acts as a large dead weight so I don't need to fix it to anything. Even if the water supply is cut off, the bucketful can last for days.

Now it may be getting even better and more interesting. I'm going to build a reliable circuit so I can get rid of the adapters and the timers. There will only be one power supply, which can be AC indoors, DC outdoors or battery operated. Before that it's a bit daunting to set up all the timers and adapters and boxes.

Nowadays it's amazing with the net. You get electronic components from 1 to 1 million over the Internet, and you are welcomed the same. And there's the online datasheets for you to design like a pro. There are free circuit design software for you to download so you will be biased to a supplier's components. Then some other free software will turn your design into state of the art circuit boards. It's a little expensive to make a single product. But if you make a few to give it to family and friends, the cost isn't that bad.

Inevitably, I can't rely on cardboard boxes. They have to be replaced all the time. Again thanks to the Internet, you can use any materials you desire, from carbon fiber to metals to plastics. You just draw your parts on a free CAD package, push a button, and the price will be quoted to you. For my case acrylic is suitable. I can cut and glue it myself or I can find laser machines to cut the pieces for me with high precision.

If I go through with these, someday I may get rid of the bucket and turn the automatic waterer into a sculptured acrylic fountain.

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