As requested by some, I'll briefly explain how the automatic feeder works and how it was built.
The idea came from commercial feeders. However, I modified one I already had, at no cost. I had the materials at home, such as wire mesh, marine plywood, pieces of pallet, wire, a few wood screws, and threaded screws with 4 mm nuts.
Since mice have been multiplying lately, and any leftover chicken food (cracked corn) is quickly eaten by field mice, I modified the feeder by adding this mechanism, because the chickens are always hungry because there wasn't enough food to put in.
With this system, the food in the feeder is only for the chickens because the weight opens the metal mesh door.
If the mice were smart and organized themselves together, one on top of the other like in a circus, they would climb onto the swinging platform, and a few mice would manage to eat... but let's hope they don't get that far...