Help designing daily cow feeder :)

[subiej]

Ok, a small challenge for you people who know what you're doing, here. Honestly, I made a good effort to figure this out myself, but I really don't know a lot about home automation, and have smoke coming out of my ears.
 
I am interested in creating a system for feeding my family cow while we are away. I'm thinking it will consist of a (strong!) bin, full of hay, with a lid that is under tension (to open it) by some simple springs, but held closed until the designated time by an electromagnetic lock like the "Seco-Larm E-941SA-80Q Mini Maglock, 80 lb." on Amazon (sorry, not allowed to post a link), which needs its own power supply.
 
My hope is to design a system in which, at a designated time, the lock will be released (i.e. the power will be shut off), thus releasing the lid, and popping the lid open, for the cow to eat.
 
I can figure out how to make a system for a *single* bin– and a single feeding–with a simple timer from the hardware store. But the goal is to create a *series* of bins, to be programmed for various days, e.g. 6pm every evening every day of the week, or even for various mornings and evenings, a week in advance. 

Can anyone give me an idea of what direction in which I should be looking to accomplish this? Do I need a controller that can handle multiple circuits (this seems like overkill, and very expensive!), as well as a separate power source and lock for each circuit? Or perhaps I am on the wrong track altogether? Yes, they sell very expensive automatic feeders online, but seriously, this is not that complicated– it seems like I should be able to make something like this myself.
 
My apologies for what may be a silly question. If anyone has any gardening dilemmas, I am happy to help :/
 
Thanks-
Susan
 

 

[RAL]

Hi Susan -
 
Welcome to Cocoontech!
 
When you talk about a series of bins, do they open at different days?  i.e. one bin that opens on Monday, another on Tuesday, etc?   Would you ever have more than one that opens at the same time?  Bins that open at the same time on the same could be controlled by one timer, but each bin would have its own magnet.
 
Once this bin is open, does it need to be closed automatically?  Can't do that easily with tension springs and an electromagnet.
 
After 7 days, would you have the cycle repeat itself, or would you program a new series of times?
 
You could have one power supply that powers all of the magnets, if it is large enough to handle the load.  Each of the Seco-Larm magnets to specified needs 12 Volts at 0.085 Amps, so if you have, say 4 bins, you would need a power supply that can provide 0.085 x 4, or 0.34 Amps.  Such a power supply is easy to buy.
 
You could use some timer control boards to activate each of the magnets (actually, deactivate them).   Something like the Altronix PT724A is one possibility.   You would need one for each magnet.
 
There are also multi-channel timers that can control more than one magnet.  One example is the Altronix AT4B, which can control 4 devices.
 
These timers are more expensive than the simple appliance timers you would find at your local big box store, but they are designed to last.

 

[Neurorad]

Whatever you decide on, have a backup plan, like a neighbor kid for $10/day. Monitor with a cheap camera, see if something goes wrong.

Single cow? Doesn't she need milking too? Or beef cow? 4H project?

How many days in a row?

 

[RAL]

Neurorad brings up a good point about what happens if something goes wrong. 
 
If there was a momentary power failure and all the bins opened at once, would that be a small problem, or a big problem?   If it's a big problem, perhaps a different way of keeping the bins closed would be better, such as a deadbolt mechanism that retracts for a moment to allow the springs to open the bin.  But if there was a power failure, the deadbolt would stay engaged, since it would only retract when the timer provided power at the proper time.
 
It's easy to evolve this into a more complicated system that would have monitoring to keep checks on whether the bins actually opened when they should open, and/or somehow opened at the wrong time.

 

[JimS]

As RAL noted, requiring power to keep them closed will be an issue if (when) power is lost.  Better to use power to trip a latch to open.
 
How about something like this:
https://www.youtube.com/watch?v=XVHQijx6KoI
Not much detail but it's a start.
 
Maybe a sprinkler timer and 24VAC door strikes (release when powered).  Maybe you don't have AC power at this location.  You didn't give us much detail.
 
Google is your friend.