(SKU:RB-04M008)RB-421 Standard Servo

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Product introduction

RB-421 Standard Servo is used for jointing 2DOF robot. It is the Alsrobot newest generation of standard 180 degree rotation motor servo, which features brush DC, coreless motor, internal non-iron rotor, high energy conversion efficiency, high activating braking response speed, reliable operation stability, good adaptive capability, low electromagnetic interference, small volume, light weight, conductive plastic potentiometer with good precision. The motor’s integrated circuit (IC) adopts digital chip and power switch to make up for H bridge circuit. The voltage controls in bipolar driver mode with fast response speed, small range of non response zone, high positioning accuracy, good compatibility and anti-jamming capability which is suitable for robot and model airplane field.

Technical parameters and performance

  1. Control System: +Pulse Width Control 1500usec Neutral
  2. Operating Voltage: 4.8-6.0 Volts
  3. Operating Temperature Range:0 to +60 Degree C
  4. Operating Speed (4.8V):0.17sec/60° at no load
  5. Operating Speed (6.0V):0.40sec/60° at no load
  6. Stall Torque :( 4.8V):2.9kg·cm ;( 6.0V):4.6kg·cm
  7. Current Drain (4.8V):7.6mA/idle and 160mA no load operating
  8. Current Drain (6.0V):7.9mA/idle and 190mA no load operating
  9. Dead Band Width: 20usec
  10. Connector Wire Length: 300mm
  11. Dimensions: 40.2mm X 20.2mm X 43.2mm
  12. Weight: 50g

Dimensional drawing

RB-421 Standard Servo Motor dimensional drawing

Su liao chi duo ji 01.png

Note: All dimensional drawings are manual measured, used for reference only. It should be considered that a margin of error is inevitable.

Interface definition


Methods of use

Required hardware

  • RB-421 Standard Servo Motor *2
  • Carduino UNO controller *1
  • Sensor Shield V5.0 *1

Hardware Connection

Connect the 2 servo motors to the pin D8 and D9 of the controller.

Sample Code

#include <Servo.h>
Servo sv5; 
Servo sv9;
const int sv5Pin = 8;  // sv5 接 Pin 8
const int sv9Pin = 9;  // sv9 接 Pin 9
const int every555 = 15;
const int every999 = 50;
unsigned long last555 = 0;
unsigned long last999 = 0; // last moving time
int dir5 = 1;
int dir9 = -1;
int pos555 = 90;
int pos999 = 90;
void setup() { 
   Serial.println("Test 2 Serbo");
void loop( ) {
  check555( );
  check999( );
void check555( ) {
   if(millis( ) - last555 < every555) return;
   last555 = millis( );
   pos555 += dir5;
   if(dir5 == 1){
      if(pos555 >179) dir5 = -1;
      if(pos555 < 1) dir5 = 1;
void check999( ) {
   if(millis( ) - last999 < every999) return; 
   last999 = millis( );
   pos999 += dir9;
   if(dir9 == 1){
      if(pos999 >179) dir9 = -1;
      if(pos999 < 1) dir9 = 1;

Application effect

Control rotation speed of the 2 servo motors with Arduino, making one rotation speed reach 50 milliseconds/degree, the other stay at 15 milliseconds/degree.

Video Tour

Duo ji dui bi01.png
RB65PG 01.png

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Purchase link

RB-421 Standard Servo Motor

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