After many years of accumulating electronic bits and pieces, I thought it may be useful to have a list of different components grouped by their purpose.
So here it is!

Motors

Servos

  • SG90g - micro servo, useful for small loads
  • LDX-227 - 15KG ~ of torque, useful for robotic applications because comes with brackets
  • LD-20MG - 20KG torque servo

Servo drivers

  • PCA9685 - drives up to 16 servos

Steppers

  • 28BYJ-48 - a 5V stepper motor useful for small tasks
  • NEMA17 - a classic
  • NEMA23 - very beefy stepper motor

Stepper motor drivers

Have a look at this article on the arduino forum for a more in depth explanation.

  • A4988 - used in most CNC and 3d printer machines, drives 1 stepper
  • ULN2003 - Darlington Array driver, drives 1 stepper
  • L298N - Dual H Bridge motor driver, drives 1 stepper, generally not a good choice since it requires more pins and cannot drive high voltages.

Water/Air Pumps

  • Peristaltic pump - uses a dc motor (generally 12V) to pump a liquid through a tube, see my article

Sensors

Photoresistors

  • GL5528 - acts as a variable resistor depending on the light that shines on it

PIR (passive infrared)

  • HC-SR501 - the cheapest way for recognizing if someone enters a space

Current measuring

  • INA219 - a very handy and cheap I2C device to measure the current absorption of your circuit