Tri-Mode DC Motor Controller

 RC Power Servo Controller
RC Motor Speed Controller
Manual Motor Speed Controller via POT



Our Tri-Mode Motor Controller, can be a direct replacement for any Standard RC Servo when in Mode 1.   There are 2 Modes used for Motor Speed control. Mode 2 is used for Motor Speed control via the RC Pulse. Mode 3 is used to control bidirectional speed via a Potentiometer. Rc Servos are for controlling  DC MOTORS in Robotics, Electric Carts, Buggies, RC Cars and Animatronics just to mention few. Any inexpensive 10 to 15 Volt motor can be used. Rc Hobby Servos are the most popular and inexpensive choice for building Robots and Animatronics Devices.  However, torque (power) is limited when using a Futaba or other small Servo. Larger and more powerful motors are essential to achieving this. Using more powerful motors necessitates the use of velocity ramping.   To bring a large weight into motion, we must match motor torque to motor load. Our Rc Power Servo Controller will do this by slowly increasing the speed of the motor, which is known as Up-Ramping or Soft-Start, and do the same to slow it down by Down-Ramping.  Basically we need to control the Speed when we want to go from one servo position to another. This also applies if in Speed Mode.

Scema-Servo-ReversalWe also have to prevent the motor from instantaneously reversing direction. When a servo runs at full speed in the forward direction and we tell it to go to a position in the opposite direction, we must first process the Down-Slope, only when the servo motor comes to a stop can we reverse direction and process the Up-Slope. This is necessary to allow robots to move fluidly and avoid stress or damage to gears, levers and pulleys.


  • Input 1: RC Pulse 0.9ms to 2.1ms and 5 to 6 Volt Controller Power Input
  • Input 2: Potentiometer, linear 2.5 to 25 Kohm for Position Feedback.
  • Motor Supply Voltage: 10 to 15 V DC (12V DC Recommended)
  • 25 Amps Maximum Continuous Current   (40 amp search current)
  • Efficient H-Bridge design using Four High-Power MOSFETs • PWM Duty Cycle: 2% to 100%
  • Built-in soft-start feature. Up-Slope and Down-Slope. Can be disabled.
  • Motor Reversal Protection. Can be disabled.
  • Complete Optical Isolation from motor power and RC Pulse input signal.
  • Power-Up safe start feature. Motor will only start if pulse of 1.5ms present.  Can be enabled.

User Programmable Parameters:

Not all Servo Applications are equal. Some are for moving large weights, torque being the main criteria. Others are for quick responding applications like Power Steering. Velocity being the main criteria. Every application needs varying degrees of Velocity Ramping. You can select and program 5 different settings.  For some applications, like power steering, sloping is not wanted or can be a hindrance. Both features, Sloping and Reversal Protection can be disabled.

There is also a Start Up Safety Protection Feature that is off by default but can be enabled. The controller will not arm the motor until it receives at least one valid RC Pulse of 1.5 ms. This prevents your Robotics from going a mock and cause serious damage. This can occur if you apply power before you activate your RC Controller. The RcPowerServo H-bridge is designed for high load applications where efficiency and capacity are critical factors. This bridge has a continuous current capacity of a 25 Amps and can drive motors rated from 10 V to 15 V. It is primarily designed for low cost 12 V DC Motors.  Automotive actuator motors like Wiper and Power Window Motors have worm gears and are ideal for high torque robotic applications.

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