Quantity   Component name
1 × Arduino Pro Micro Cat feeder brain
1 × ESP8266 WiFi module for polling the cloud server for feeding times
1 × DC motor with crank arm Drives the feeding piston
1 × AMS1117-3.3V step-down buck module Dropping the input voltage to a friendly 3.3V level for the ESP8266
1 × 3.3V zener diode 5V to 3.3V Level-shifting for the ESP8266 serial transmission
1 × 330 ohm resistor Part of the level-shifting circuit
1 × Piezo speaker Plays a short melody when food is served to lure the cats in (and for a little Pavlovian experimenting).
1 × Pebble smartwatch Feeding times can also be set with a simple pebble.js app.
1 × SN754410 Motor controller (actually a bit too flimsy for this purpose as a stuck motor will quickly burn the chip)