Avoid Servo Glitches with the LM2596 Power Module (Classroom Guide)

Audience: STEM teachers and facilitators building Arduino-based robots with SG90 or similar servos.

Nothing derails a lesson faster than a robot that jitters, randomly resets, or won’t steer when both servos move. The cause is usually voltage sag from powering servos directly off the Arduino’s 5 V pin. The fix is simple and reliable: use an LM2596 step-down (buck) module tuned to a steady 5.00 V and wire servos to that supply, not the board’s regulator.

🧩 Reference guides: LM2596 Power Module • SG90 Servo Guide • Technical Centre

Why the Arduino 5 V Pin Isn’t Enough

Small servos like the SG90 can pull 300–500 mA when starting or under load. Two servos plus sensors can momentarily exceed what USB or the Arduino onboard regulator can supply, causing brownouts (resets) or jitter. A dedicated, efficient supply keeps voltage stable during these spikes.

What the LM2596 Does

• Steps down higher battery voltage (e.g., 7–12 V) to a regulated 5 V rail.
• Provides higher current than the Arduino regulator, ideal for multiple servos.
• Runs cool and efficient; easy to tune with the onboard potentiometer.

Safe Classroom Wiring (Text Diagram)

[Battery 7–12 V +] ──> LM2596 VIN+
[Battery 7–12 V –] ──> LM2596 VIN–

LM2596 VOUT+ (5.00 V) ──> Servo + (red) and 5 V rail
LM2596 VOUT– (GND) ──> Servo – (brown/black) and GND rail

Arduino 5 V ──(do not power servos from here)── ✖
Arduino GND ──> Common GND rail (shared with LM2596 and servos)

Servo signal (orange/white) ──> Arduino D9/D10 (only signal wire)

How to Tune the LM2596 to 5.00 V

1. Disconnect servos. Power the LM2596 from your battery/adapter.
2. Use a multimeter on VOUT+ / VOUT– and adjust the small screw until it reads 5.00 V.
3. Label the module “5.00 V – Servos” with tape to prevent student mix-ups.

Tip: If your lesson uses a microcontroller that prefers 3.3 V logic, you can still power servos at 5 V. Only the signal wire connects to the controller; the grounds must be shared.

Stability & Safety Add-Ons

• Bulk capacitor: Add a 470–1000 µF capacitor across the 5 V rail near the servos to absorb transients.
• Inline fuse: A 1–2 A fuse on the battery’s positive lead protects against accidental shorts.
• Wire gauge: Use thicker wires (22 AWG or better) for power runs to reduce voltage drop.
• Distribution: Use a small terminal block or breadboard power rail for neat, consistent wiring across teams.

Minimal Servo Test Sketch (Verify Power Before the Full Build)

#include <Servo.h>
Servo leftS, rightS;

void setup() {
  leftS.attach(9);
  rightS.attach(10);
}

void loop() {
  leftS.write(90);  rightS.write(90);  // neutral
  delay(800);
  leftS.write(0);   rightS.write(180); // sweep ends
  delay(800);
}

Run this with wheels lifted off the desk. If motion is smooth and the board doesn’t reset when both servos move, your power rail is stable.

Common Classroom Problems & Fixes

• Board resets when servos start: Grounds not shared or servos powered from Arduino 5 V. Share grounds and move servo power to LM2596.
• Jitter when turning: Voltage drop on long, thin wires. Shorten power leads; use thicker wire and add a bulk capacitor.
• Some teams fine, others glitchy: Mixed power strategies. Standardize on a tuned 5.00 V LM2596 for all robots.

Lesson Extensions

• Engineering log: Have students record voltage under load (multimeter) and correlate with behavior.
• Design challenge: Compare LM2596 vs. USB-only builds and present findings on reliability.
• Safety module: Quick demo on fuses, polarity, and capacitor orientation.

For printable wiring diagrams, a tuning checklist, and spec notes, visit the LM2596 Power Module guide and the RoboRider Technical Centre. Pair this setup with our SG90 Servo Guide to eliminate jitter before students start coding.

Quick Checklist for Teachers

• Servos powered from LM2596 at 5.00 V, not Arduino 5 V.
• All grounds shared (Arduino, LM2596, servos).
• Bulk capacitor on the 5 V rail; thicker power wires.
• Verify with the minimal sketch before integrating sensors and logic.