Saturday, Jan 13, 2013

Feeding the Cat like an Evil Mad Scientist

I like to use an automatic cat feeder so my poor kitty doesn't go hungry if I am delayed at work or decide to stay out late (or sleep in). My first attempt using a store-bought was really unsatisfactory: the dispenser timing, and thus food output, was controlled by a fiddly trimpot and, worse, a roller mechanism that just was not reliable: surely there's a German word for the guilt you feel when your pet goes hungry from your crummy technology.

My nephew, who is fond of sweets, has a prized posession: a Brookstone Candy Man automatic candy jar designed to dispense jelly beans. "Or CAT FOOD!" I said to my nephew, who responded with the appropriate moue of disgust. Ah -- but I was serious! Not only was it dashing red in an elegant egg shape but it has an auger feeder that was simply better than my existing unit.

The only task was to automate it, and for this I turned to science. Evil Mad Science, to be precise. They have a super cool "Art Controller" (actually suggested by my art pals Nemo Gould and CTP) that would do just the trick. It is a circuit board kit that has but one purpose: to close a switch for a programmed amount of time. It even has a jumper to set the board to close the switch on power up which is exactly what I needed as I already had a timer set up.

Guts of the automatic feeder

Well, I will spare you the details (which are reasonably obvious) but I hooked up the motor to the timed switch, and set it to run for seven seconds when it gets power, as it does when triggered by a timer. Since I had a 5V power supply I removed the voltage regulator from the art controller and used the holes for pin headers to connect the existing power supply and motor wires. The resulting hack will reliably and elegantly deliver meals to my favorite pet.

TT eating from feeder

Well, as usual with a project of this sort there are a number of enhancements that could be made: most inconveniently I need to disassemble the unit to change the timing: making the timing switches accessible would be a nice addition. A "snack" button that would dispense food when pressed would be nice, but I can do that just by turning on the unit from the timer. One final enhancement: there is a white LED that illuminates the output slot that could be turned on when the unit is operating. While that might be a nice feature for humans, I'm confident my cat could find the food dish even in the darkness of interstellar space.



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