Looking for some guidance on where to go next with a project. I've made an automatic feeder for some barn cats. It uses an AC outlet timer to energize a 555 timer once a day for 30 min. I have the RC circuit for the 555 setup such that it runs on initial startup for a certain amount of time depending on potentiometer setting then shuts off for the rest of the 30 min time. This goes through a relay which drives a geared DC motor on an auger.
Functionally it works and have been using it for about 6 months. The problem is the motor speed is not constant. As the hopper empties over time, the load on the motor decreases, so it speeds up, and gives more food as the it empties (over about a 2 week time frame). I don't see a good way to change the hopper design to keep the load constant over time.
I'd like to make a version 2, with these fixes. I'd like to keep the circuitry costs under $20 if possible. I may end up making a few of these for other people and will probably have another $30-40 in motor, AC/DC converters, outlet timer, etc.
1) Feed a fixed amount of food even as load on the motor changes. I could see a few ways of doing this - motor speed with feedback (either rotation counter or back EMF), instead of shutting the motor off after a certain amount of time shut it off after xx motor rotations.
2) It would helpful if I could get rid of the AC outlet timer. It's not critical if the start time drifts day to day.
I need some help understanding what a good option to pursue is. I'm still a beginner for the most part but if can get a general idea of what direction I need to go, can typically get it functioning. I've read a bit on motor speed control (there's tons of options), a bit about PIC's (a bit over my head at this time), and some low cost Aurdinos. The Arduino pro mini is interesting, as I have an Uno and a couple motor drivers and could play on that before buying more hardware.
Functionally it works and have been using it for about 6 months. The problem is the motor speed is not constant. As the hopper empties over time, the load on the motor decreases, so it speeds up, and gives more food as the it empties (over about a 2 week time frame). I don't see a good way to change the hopper design to keep the load constant over time.
I'd like to make a version 2, with these fixes. I'd like to keep the circuitry costs under $20 if possible. I may end up making a few of these for other people and will probably have another $30-40 in motor, AC/DC converters, outlet timer, etc.
1) Feed a fixed amount of food even as load on the motor changes. I could see a few ways of doing this - motor speed with feedback (either rotation counter or back EMF), instead of shutting the motor off after a certain amount of time shut it off after xx motor rotations.
2) It would helpful if I could get rid of the AC outlet timer. It's not critical if the start time drifts day to day.
I need some help understanding what a good option to pursue is. I'm still a beginner for the most part but if can get a general idea of what direction I need to go, can typically get it functioning. I've read a bit on motor speed control (there's tons of options), a bit about PIC's (a bit over my head at this time), and some low cost Aurdinos. The Arduino pro mini is interesting, as I have an Uno and a couple motor drivers and could play on that before buying more hardware.