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Wilson Mar

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Rain down food from above, automatically



Here is (the beginnings of) a description of how I made it happen, so you can, too.

Why drop stuff from the ceiling?

There are several reasons why someone would want to drop stuff from the ceiling. Balloons at a celebration. Red liquid at a Carrie” movie remake.

Or hay for animals in a barn, which is my interest here. I have a barn for two donkeys. My wife gets up before dawn each morning to feed them, or they will bray annoyingly.

We can’t leave a lot of food laying around because they eat everything they can reach.

Thus, I want a box above the animals to hold their hay for release automatically at a set time.

(BTW, my wife’s against all this automation because she says she has to get up anyway for other chores with the chickens and ducks, etc. :) Anyway, I’m undeterred by practicality. So read on.

This post talks about a trap door held by a pin attached to a solenoid. A quick pulse releases it. A transistor or MOSFET to drive the release to protect the Arduino from excess current or spikes.

One video shows how to release from an RC plane a parachute release mechanism using a 9 gram servo with an armature arm with a wire that holds (until release) a rubber band that holds the package.

How it works

Here’s a wish list:

  1. The shelf is raised and lowered by four ropes, one on each corner.

  2. During the dumping (feed) operation, only one side is fully lowered so whatever is on it slides off.

  3. The release if a vertical door is needed to hold enough stuff without spilling over.

  4. We use two sets of pulleys, one for each side. Pulleys enable a smaller motor to be used.

  5. Safety wire cables keep the shelf from crashing to the floor ?

  6. Like a garage door, lasers sense whether there is something in the way before the platform is lowered.

  7. Two stepper motor controls each of 2 sides of the platform. Both would operate to raise or lower. Only one would operate to dump contents.

  8. A bell sounds before the food is dumped so the donkeys know to avoid the dump. Right.

  9. Sensors identify if conditions are safe - the position of the various parts (motor) and whether each is still working.

  10. There would be logic on the Ardunio board that to not do something if sensors indicate.

  11. In “productive mode”, when it’s time (5 minutes before dawn each day), the shelf is emptied automatically by lowering one side and releasing a latch.

  12. There should be a manual alternative to lower the shelf and open the door. That’s in case of loss of electricity or when the computer part doesn’t work.

  13. In “test mode”, we would press a button to raise it; another button to lower it; and a third button to dump the food. This could be a multi-purpose button where one tap raises, two taps lowers it, and a long press to dump from above.


  • [__] $30 from Home Depot one finished sheet of 3/4 inch pine plywood - 4x8 foot or 48 x 96 inches used for framing.

    At 2.5 pounds per square foot, the whole sheet weights about 84 lbs.

  • [__] Have the yard make 4 cuts. Cut it in half along the long edge for a 48x48 inch square shelf, then cut the four 12x48 slats for the walls and door.

    QUESTION: Does this provide enough volume to hold enough feed? We would need enough space to hold enough for a single meal for two donkeys. Maybe 3.

  • Make a 45 degree edge on each of the 3 side boards.

  • [__] $0.58 from Home Depot 14 galvanized steel L brackets. Attach 3 each of 3 to attach the 3 sides to the base.

  • [__] 192 wood screws (4 each for 14 brackets), 1/2 inch long with tapered head.

  • [__] Drill a hole on each of 4 corners.

  • [__] 4 eye rings on the top of the sides for ropes to attach to the box.

  • [__] Hinges for the door.

  • [__] gear motor actuator to lock and release latch.

  • [__] Install the door release with a cable to the Arduino.

    A hoist for a bicycle of about 100 lbs. is $20 from Amazon. Two sets should support 200 lbs, right? But that may not be enough for the platform.

  • [__] 4 sets of block and tackle pulleys for 1/2 inch diameter size rope. $21 each from Amazon.

    The four wheels provides 7:1 lifting ratio power for 2 tons of working load capacity.

  • [__] Bolts on the ceiling to hold the pulleys should be braced to support that.

    Additional bracing may be needed for your ceiling.

    Check with a construction specialist.

  • [__] 4 ropes to lower the platform almost to the ground. Although the height is about 10 feet each, about 4 times that is needed to go through the pulleys. So we get a standard size rope of 100 feet (30.48 meters).

    The 1/2 inch climber ropes are about $30 used, $40 new on Ebay

    • Measure the weight of the platform with ropes at maximum load. The estimate is 100 pounds max.

    How to move the rope electronically?

  • [__] TODO: Stepper motors sized to handle the weight.

  • [__] Sensors to detect slippage.

  • [__] Notification

  • [__] Arduino board to signal the stepper motor.

  • [__] Power supply






  1. Blue wire DC-

Servo vs. Stepper Motors

The Arduino website explains Servos have integrated gears and a shaft that can be precisely controlled. Standard servos allow the shaft to be positioned at various angles, usually between 0 and 180 degrees. Continuous rotation servos allow the rotation of the shaft to be set to various speeds. The Servo library supports up to 12 motors on most Arduino boards and 48 on the Arduino Mega. On boards other than the Mega, use of the library disables analogWrite() (PWM) functionality on pins 9 and 10, whether or not there is a Servo on those pins. On the Mega, up to 12 servos can be used without interfering with PWM functionality; use of 12 to 23 motors will disable PWM on pins 11 and 12.

This video explains: A stepper motor is used in applications requiring about 2000 rpm or less where you need a lot of torque at the low end, where as a servo motor is typically used for your higher speed applications that are more dynamic and require more acceleration and deceleration typically 2000 rpm and higher.

A servo is always built with a feedback mechanism.

  • https://www.youtube.com/watch?v=oOvRf7xa5r4

YouTube video: Practical Insight in selecting stepper motors for your build describes the difference between NEMA (National Electrical Manufactures Association) stepper motor numbers:

  • NEMA 17 is 1.7”
    holds 53 ounces of weight

  • NEMA 23 is 2.3” takes a #10 machine screw
    holds 425 ounces (26.5 pounds)

  • NEMA 34 is 3.4” takes a 1/4” screw
    holds 1232 ounces (77 pounds)

Some salvage the motors from scrap copy machines


  • http://www.leevalley.com/US/wood/page.aspx?p=74353&cat=51&ap=3

More on IoT

This is one of a series on IoT:

  1. IoT Acronymns and Abbreviations

  2. IoT Apprentice school curriculum
  3. IoT use cases
  4. IoT reminders prevent dead mobile battery
  5. IoT ceiling dumper

  6. IoT text to speech synthesis
  7. IoT AWS button
  8. Intel IoT
  9. IoT Raspberry hardware
  10. IoT Raspberry installation

  11. IoT Clouds
  12. Samsung IoT Cloud

  13. Predix basics
  14. Predix installation
  15. Predix services
  16. Predix programming