The Arduino is a microprocessor. It is like a simple miniature computer. The Arduino sends pulses to the motor driver that tell the motors when to move. There is no input to the Arduino, so the machine keeps juggling the same way regardless of whether or not there are any balls.

All the wires connected to the Arduino are skinny. The Arduino uses small amounts of current.

This is an $8 stepper motor driver. The driver has several screw terminals in the green plastic. The screw terminals have two sections; high voltage and low voltage. The signals from the Arduino come in to the low voltage terminals. Signal --> Low voltage. The power from the 24v power supply and the wires to the stepper motors go in and out of the terminals in the high voltage section.

The insert shows the six switches on the motor driver. The switches can adjust these parameters:

• steps per revolution
• power

I am using 800 steps per revolution. This is a optimizes speed (fewer steps per revolution) and smooth running (more steps per revolution).

I am using the 1Amp power setting (max is 4Amps). Higher power settings are noisy, and there is a lot more vibration. When I use lower power settings, the stepper motors skip steps. The stepper motor doesn't have enough power to throw the ball and it looses it's position. At 1Amp the motor runs smooth, but doesn't skip steps.

These are NEMA-23 sized stepper motors. They are rated for 2.0A.

This component supplies power to the stepper motor drivers. The input power comes from the 120v60hz AC utility power (house mains). The output power is 24v DC.

This 5v power supply is a repurposed cell phone charger. It supplies power to the Arduino. The utility power is converted into 5v DC for the Arduino.

There is a switch for power to the Arduino, and a switch for the power to the motor drivers. To run the machine, both switches are turned on.

To test the motor, only the high voltage switch is turned on. To test the Arduino, only the low voltage switch is turned on.