Electromechanical Systems·2025–2026
Automatic Tennis Ball Shooter
↗Designed and fabricated a client tennis-ball launcher prototype at BrainChild Engineering integrating ESP32 wireless control, dual RS-775 flywheel drive, NEMA 17 stepper feed, MOSFET motor switching, and 12V-to-5V power regulation into a modular electromechanical system.
Motivation: I built this at BrainChild Engineering for a client demo that had to leave USB babysitting. The work meant migrating from an Arduino Mega / Bluetooth path to an ESP32 that owned motor sequencing; driving dual RS-775 flywheels through MOSFET modules under MCU PWM instead of pot speed controllers; indexing balls with a NEMA 17 on an A4988; and splitting a fused 12 V pack so actuators stayed on the high rail while a buck fed 5 V logic. The MOSFETs are hard switches: PWM duty cycle sets average motor voltage, and the motor’s inductance / inertia smooth the pulses. Failures taught as much as the architecture: no buck at first left the ESP32 dead on battery, the stepper print was too flimsy until a denser reprint, and a PWM test oversped a motor so hard that the fuse did not open, buck / battery solder joints came off, and a wire melted. It stayed a prototype on purpose: enough for a Replit-controlled multi-motor demo, not a finished consumer launcher.
Challenge: 12 V pack without a buck converter left the ESP32 unable to run correctly off battery.
ESP32C++NEMA 17 StepperA4988RS-775 DC MotorsMOSFET Modules
ShippedClient prototype / demo