I am needing to design and build a solenoid based hay feeder for the two rabbits I own.
Essentially, It will be a swing trap style with 4 compartments holding hay (its not a huge size, it is not like the horse hay feeders - half that).
Each tray will be held by a solenoid and released on a timer. (every 2 days). I will be using a 4 channel relay to control each solenoid motor and ONE Arduino Mega controlling them all.
My question is how to go from here (i am still new at this all):
1: do I need a MOSFAT?
2: will the 4 channel relay work with a timer delay that is days, not seconds?
3: Will i need a RTC too? some say yes others say no.
4: Are there otehr components that are needed?
5: Would the 5v solenoid hold up a trap door plus hay weighing about 500-1kg. or will i need a 12v. In that case would a 5v solenoid even NEED a relay?
You might consider using servos to operate the lock mechanism rather than the combination of relays and solenoids. IMHO they would be simpler.
If you do want to use solenoids then you can almost certainly control them using Mosfets without the need for the relays. However I am not expert on Mosfets so I won't suggest any details.
if you do decide to use relays then you won't need the Mosfets. (I assume you are referring to the usual Arduino - compatible relay modules).
For times that run into days an RTC is essential - the Arduino's internal clock is not good enough.
The ability to hold the weight of the hay depends mostly on the mechanical design rather than the electrical components. Imagine, for example, a sliding bolt that can be pulled out by a servo or solenoid. The bolt is what takes the weight.
It would be wise to have some means to notify you if the system fails so that the animals don't starve.
Each tray will be held by a solenoid and released on a timer. (every 2 days). I will be using a 4 channel relay to control each solenoid motor and ONE Arduino Mega controlling them all.
Hope you mean the solenoid will pull a catch to release the feed and not be ON all the time until you need to open the bin.
How will you power this project?
The 12 v solenoid may have more power.
You will need to have two separate power supplies.
The Arduino is nest to be powered by a cell phone charger.
The relay module should be separate.
The solenoids may be able to share the same power supply as the relay module.
If you have not purchased parts then i would suggest you post a link to the parts you are considering.
The solenoids will draw power as will the relay module. But if you will only have one relay and oone solenoid powered at a time the power supply may be smaller
No MOSFET is needed as the relay module has them already
Unless you already have the Arduino Mega, you do not need anywhere near the capabilities of that board for this project.
It would be a bit more complex to implement, but you might want to use a board with WiFi capability, such as an esp8266 based board, then you can send status updates if the feeder malfunctions, and sync the onboard clock from an NTP time server, eliminating the need for an RTC.
