Hello, I am new to all this. My daughter is working on an invention for school that is a homemade automatic pet feeder. It is a plastic bottle where the bottom has a CD attached with an opening for the pet food to be released. After looking at what others have done, I think a continuous servo motor would work well for this but my daughter has her heart set on being able to program it to dispense food at a set time as well. I believe an arduino board will do this. I’ve done some programming but have never worked with something like this. I don’t know which servo motor or arduino board to get. I am not sure how to attach said servo motor to the board and what would be the power source. Any help would be appreciated. Thank you.
the Arduino can drive R/C servos. A data pin, ground and power connection are required. Arduino library supports these servos. You’ll need some sort of position feed-back to know where your disk (CD?) is. Punch holes, photo-interrupter sensor.
Alan KM6VV
Thank you for your quick response.I apologize for the vague picture but I could not illustrate it here. The project must be done with as much homemade parts as possible hence the CD 
. Basically there is a large plastic bottle with the end cut off, the servo will be attached to the CD (which will have a hole in one part) to make it rotate. I do have Arduino code to make it rotate at a specific time but the actual parts is where I am a little vague . Which servo would you suggest for this project? Would any Arduino board work for this? You mentioned the data pin, ground and power connections are required, are these sold together or separately? is there a specific type that I should look for? I assume this will be attached to a power source(batteries)? What is this called? and what does a photo-interrupter sensor do? and where would this go? I need to have an idea of what actual parts I need. Thanks.
It really depends on the design. Most use an auger approach like this one, which has the motor connected to a large screw which essentially pushes food out the front tube:
robotshop.com/en/autopetwate … =RB-Erg-04
You don’t need any positioning really and just time the motion.
If you can create of find the auger and tube, this setup is really reliable and easy to make.
The approach you are thinking about relates much more to candy vending machines (image attached).
Instead of rotating in a continuous circle, you can use a normal 180 degree servo which moves back and forth.
This design is less reliable because it’s easier for food to become jammed.
If the current required by the motor is >40mA, the Arduino should not be used to power it directly, but can certainly send the position signal.
