Monday, December 21, 2015

Micro-USB Powered Dog Feeder

I'm not a huge fan of stationary devices that require batteries to operate. I've had 2 Aspen Le Bistro Portion-Control Automatic Pet Feeders since February of 2015 and they've performed very well. The only problem is that when the batteries get low, they don't feed the dogs and so far, the low battery light hadn't worked. The label on the bottom of the feeder clearly showed I needed 4.5V at 500ma to power the feeder. To anyone who works with electronics, these numbers are almost identical to USB power (5V at 500ma) which gave me the idea.

Stock image of the female Micro-USB

I ordered 2 micro-usb female connectors from Adafruit. There are cheaper versions on Amazon but these had large connector tabs for soldering and gave me a stronger point for connection.

I removed the 4 screws in the base of the feeder and opened it up to find a very easy and spacious working environment with clear pathways and simple clamp on connectors for the power leads.

It fits!
I decided to put the hole for the micro-USB port in the recessed base to protect the head of the cable. I eyeballed the connector and went to town with my Dremel, cut and fit, cut and fit.

Next I needed to determine the polarity of the USB cable and verify I was getting the expected 5V.

I cut some wire and soldered it to the micro-USB port, then did a sanity check to make sure I was getting power through the wires.

With everything in place, I routed the wiring through the hole, slid the included port cover over the remaining connector body and slathered the port with hot-glue to hold everything in place, provide support and electrical isolation.

I disconnected the clamps from the battery terminals and curled the ends of the jumper wires I had soldered to the USB port so they would fit nicely in said clamps. I gave them a little squeeze with my pliers and slid the isolation covers over the connector.

I reassembled the container and have it working from a spare micro-USB charger (who used 500ma anymore?)

My next challenge will be to provide battery backup in case the power goes out.

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