Automatic Pet Feeder





Introduction: Automatic Pet Feeder

About: Like inventing, woodworking, tractor gadgets, gardening, making Youtube videos, wind turbines, ham radio, making instructables, etc

I needed a reliable fish feeder for my pond for when I'm away.  This instructable gives details on the feeder that I just finished building and testing.  The same idea could be used for feeding other pets or for an indoor aquarium. I made a number of internet inquiries to find out details on the microwave carousel motor that I planned on using to drive the auger.  The problem with the motor is that it will often reverse rotational direction when it is turned ON and OFF and ON again.  I learned from internet contacts that a ratchet would solve the reversing problem so that is what I ended up using here.  A short demo near the end of the video (below) shows me stalling  the motor to reverse direction.  Some microwave carousel motors work directly from the line voltage in which case you wouldn't need a transformer.  However I feel comfortable with the lower voltage setup for this application as it gives an extra level of safety when the feeder is operated outdoors.  The electronic timer allows programmable  ON and OFF  times for the motor.  (Better still if you have or can find a gear head dc motor the rotation direction is controlled just by reversing the polarity of the connections.)

I decided to change the name of this instructable to Automatic Pet Feeder from Automatic fish feeder as viewers are using the idea to feed other things...

In any application like this it is important to plug the timer into a ground fault circuit interrupter (GFCI) electrical outlet.

Step 1:

Step 2:

I had an old 7/8 inch diameter auger-type wood drilling bit on hand and figured it would work fine for the size of food pellets that I normally  feed the trout.  I needed  a plastic container that would let the drill bit stick out from both sides of the container.  The two auger holes should be made as close to the bottom of the container as possible so that most of the feed will be pushed out by the auger as the supply nears the end. I drilled the large hole with a Forstner bit but the auger bit would probably work as well as long as you feed it very slowly through the soft plastic.  Before going on with the assembly I decided to check out the auger operation using the portable drill. 

Step 3:

I replaced the set screw in the drill bit stop collar with a longer screw that extends from the collar far enough to work as a ratchet tooth. Holding one of the toggle bolt wings with locking pliers made for a safe way to drill the two holes for the ratchet mounting screws.  I assembled the auger, collars, washers, and ratcheting parts in place to do a quick test of the ratcheting action.  

All of the collars are drill bit stop collars.  I got some of these in a set and they cost only a dollar or so each. The collar used in the ratcheting system is also a drill bit stop collar,  but it was selected for the ratchet because of the way the screw extends (tangent like) from the collar.

Step 4:

Here I temporarily screwed the motor mounting brackets to the pressure treated wooden base and I then temporarily clamped the motor on the brackets to do an alignment and operational test.  After a successful test, I marked, punched, and drilled the bracket holes to accept the motor. After that I  did the final assembly of the feeder. 

Step 5:

I moved the feeder to the shed next to my fish pond to do the final wiring and testing.  I found that I needed an additional (resistive) load on the electronic timer to give me reliable and consistent timing action. I plugged a lamp with an incandescent bulb into the second socket of the timer (if you have only one outlet you could use a power bar to do the same thing).  I like the electronic timer because you can very precisely set the ON and OFF times  -  also, the battery backup keeps the programs in place should there be a power failure. I'm still experimenting to find a most suitable ON time but right now it looks like 5 or 6 mins will do it.  The timer is set to repeat every day of the week.

I've conducted multiple indoor tests running the motor for long periods to see how it would react with the 16 volt doorbell transformer. The temperature rise was barely noticeable and the motor torque was more than sufficient in all of the tests.

Step 6:

Every thing is working fine so far but I want to continue testing to be sure the feeder will function reliably over 10 plus days.  My concern is primarily with the electronic timer.  I want to be sure that the program holds in place with multiple ON-OFF cycles.

The pond testing went well and the fish quickly adapted to the new feeding method.  I used a larger plastic bin to protect the feeder from the weather and critters (mainly crows and cats).  But I can't knock the crows as they have been cleaning up food pellets that the fish didn't eat .



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    21 Discussions

    One thing you may want to do in the future is replace the clear plastic tub with something more UV stable. Maybe give it a few coats of outdoor paint?

    I've found they don't cope well with prolonged sunlight. Nice project overall and makes me wonder if it could have other applications. Bird feeders, rat feeders, etc. Nice work

    4 replies

    Thanks for the ideas. I've already made a bird feeder using the same idea - you can check it out here:
    (It has also served as a rat feeder :))

    It's one of those "Oh that's so simple, why didn't I think of it" ideas that takes a light bulb moment like you must have had, followed by some good thinking to figure out how to apply it.

    Thanks - also a healthy accumulation of parts and materials to help drive the ideas on.

    hmm you should give to that plastic box some type of masking cloth


    Hi, I am interesting in this project,I hope that you can give me the circuit diagram for this, I kind of need it for my college's project.Any help,really apreaciate.Thanks.

    2 replies

    Hi Jeggeggo - here's the wiring for the timer. Did it in two forms to help you out. My timer has two 110 volt outputs They are simply in parallel. One is for the microwave motor and the other is used to provide a resistive load to the timer - this gives reliable timer operation. If your timer has just one output, use a power bar to do the same thing. Let me know if you make one.


    wow..that's really cool..thanks 4 this press this evenight...
    will give u a look when i make mine...

    Great idea. I did make a similar system to feed two cats. I used a 1" long auger bit inside a piece of 1" pvc pipe. Two notches in the top and two in the bottom allowed each cat's food to enter the auger pipe, transfer along a inch and drop out down a chute into their bowls. I had to build a funnel trough above to supply the food but it works great. I'm new to the site so hopefully I did this right and my pictures show up.... The first is from the top showing the auger in the tube, the second shows the outlet pipes dropping down and the third is the cabinet I put it in so it looks pretty.

    Cat feeder1 (640x480).jpgCat feeder2 (640x480).jpgCat feeder3 (640x480).jpg

    Real nice! Sorry for the late reply but I've been travelling. I'm able to monitor my feeder remotely on the internet and it has been performing flawlessly in automatic mode over the last three days. Kind of neat to see the feeder working from more than 4000 miles away! Do you have a video of your feeder in operation?

    I laughed out of joy when I saw you using a drill as an auger screw! Awesome instructable. It sounds like a lot of food bits get crushed. Is there a huge pile of fish food dust at the bottom when it has emptied the bin?

    1 reply

    Not much dust at all - yeah it's kind of a pleasant sound actually, maybe something like Rice Krispies on steroids :)

    Thanks - it's Tetra Pond Food intended for Koi and Goldfish but I feed it to my pond trout to supplement the food they get from nature. I also feed them worms as an extra treat as I usually have plenty of worms around the compost area.