This site’s stepper motor tutorial covers A4988 drivers and open-loop rotation — great for continuous motion where you’re counting steps. Servo motors solve a different, equally common problem in kinetic work: holding a specific angular position, and holding it against resistance, with far less wiring and no separate driver chip required.
What’s actually inside a servo
A standard hobby servo is a small DC motor, a gear reduction train, a potentiometer that reports the output shaft’s current angle, and a tiny control board — all sealed in one case. That control board is the part that makes servos simple to use: it reads the position feedback itself and runs its own closed loop to reach and hold a target angle. You never write that control loop yourself. You just tell it where to go.
One wire, one signal: pulse-width modulation
A servo takes three wires — power, ground, and a single PWM signal wire — and that one signal wire is where the entire interface lives. The servo reads the width of each pulse, not its frequency, to determine target angle:
- A pulse around 1.5 milliseconds typically means center (90°).
- Shorter pulses (toward 1ms) sweep toward one extreme (often 0°).
- Longer pulses (toward 2ms) sweep toward the other (often 180°).
Pulses repeat roughly every 20 milliseconds (50Hz). On an Arduino, the built-in Servo library handles generating this timing for you — you call myServo.write(angle) with a number from 0 to 180, and the library produces the correct pulse width on whichever pin you’ve attached it to. You don’t need to hand-time pulses yourself unless you’re working outside the Arduino ecosystem.
The power trap that breaks a first project
The single most common servo mistake: powering it directly from the same 5V pin running your microcontroller. A servo moving under load can draw a current spike well beyond what a dev board’s regulator is built to supply, and the result is usually a resetting Arduino, not a damaged servo. Give servos their own power source — a separate 5–6V supply sized for your servo count — and share only ground with your microcontroller. For more than one or two servos, this stops being optional.
Where servos beat steppers for kinetic work
Steppers win when you need many precise, repeatable, continuous rotations — a camera slider, a plotter axis. Servos win when you need a limited range of motion held firmly in place — an eye that tracks, a flap that opens to an exact angle and stays there, a puppet joint that needs to resist being pushed. If your project’s motion is “go to this angle and hold it,” reach for a servo before a stepper; it’s less wiring, no separate driver board, and the position feedback is already solved for you.
A first project
Wire one servo’s signal pin to a PWM-capable Arduino pin, power it from a separate supply, and sweep it from 0° to 180° and back using Servo.write() in a loop. Once that’s solid, wire a potentiometer to an analog input and map its reading directly to Servo.write() — now you have a hand-controlled joint, which is the building block behind most kinetic sculpture servo rigs on this site.