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Rojony Khatun
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Małgorzata Koperska, MD Steven Wooding
Last updated: September 20, 2025

DC Motor Speed Controller Circuit Using IRFP450PBF MOSFET

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IRFP450PBF MOSFET

IRFP450PBF MOSFET

A high-voltage N-channel power MOSFET with a maximum drain-source voltage of 500V and current handling up to 14A.

10K Fixed Resistor

10K Variable Resistor

Adjustable resistor with 10,000 ohm resistance

10K Fixed Resistor 1/4W

10K Fixed Resistor 1/4W

A 10,000-ohm resistor rated for 0.25 watts

[10k-fixed-resistor-1/4w]
0.22R Fixed Resistor 1/4W

0.22R Fixed Resistor 1/4W

A 0.22-ohm resistor rated for 0.25 watts

1N4007 Diode

1N4007 Diode

General-purpose 1000V, 1A diode

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DC Motor Speed Controller

Control DC motor speed efficiently using IRFP450PBF MOSFET. A PWM-based circuit provides smooth speed regulation for small to medium power motors.

IRFP450PBF DC motor speed controller

An IRFP450PBF-based DC motor speed controller offers smooth control over the speed with speed control using PWM. It works well with robotics, automation, and with small equipment that needs efficient control of motors.

adjustable DC motor speed circuit

DC Motor speed controller circuit with IRFP450PF enables the adjustment of the DC motor speed with high accuracy by using PWM (Pulse Width Modulation). IRFP450PBF is a high-current N-channel MOSFET that can easily take up moderate DC motor loads and also high DC motor loads. In this circuit, the PWM signal is used on the MOSFET gate to regulate the average voltage to be supplied to the motor. The speed of the motor can be changed in a smooth fashion by varying the duty cycle of the PWM. Bidirectional control of the motor may be achieved by optional H-bridge set-ups. This configuration is perfect for robotics, automation, conveyor belts, and hobby motors. The circuit is inexpensive, stable, and can be assembled simply on a PCB or breadboard. The MOSFET is to be bearded with proper flyback diodes and a heatsink that will guarantee consistent functioning.

Work / Installation (Inputs → Outputs)

  • Power Input → DC motor supply voltage (depends on motor rating).
  • IRFP450PBF MOSFET → Acts as a high-current PWM switch for the motor.
  • PWM Control → Adjust duty cycle to vary motor speed.
  • Optional H-Bridge → Enables forward and reverse motion.
  • Output → Motor rotates at variable speed as per PWM signal.
  • Installation → Assemble on PCB or heatsinked board; ensure proper gate signal and MOSFET orientation.

Testing & Final Adjustments

Connect the power supply and motor when it is assembled. Connect the PWM signal and test the smooth speed control by increasing and decreasing the duty cycle. Measure motor response to verify that it is functioning properly with low and high speeds. Measure MOSFET temperature; add a heatsink when needed. Ensure the flyback diodes are installed properly in order to avoid the spikes of voltage due to the inductive load. Test under different load conditions to ascertain that there is consistency and reliability in the speed regulation. Adjust fine parameters of PWM to achieve the best performance and achieve smooth acceleration/deceleration. The system is a proven and economical way of controlling the speed of DC motors.

Frequently Asked Questions - DC Motor Speed Controller:

What is IRFP450PBF used for?

It is a high-current N-channel MOSFET used for switching DC motors.

Can it control motor speed?

Yes, using PWM signals to adjust duty cycle.

Is it suitable for high current motors?

Yes, within the MOSFET's rated current.

Can it reverse motor direction?

Optional H-bridge allows forward and reverse control.

Do I need heatsinks?

Yes, recommended for high-current operation.

Are flyback diodes necessary?

Yes, they protect the MOSFET from voltage spikes.

Is it beginner-friendly?

Intermediate-level; knowledge of MOSFETs and PWM is required.

Can it be used in robotics?

Yes, ideal for robotics and automated motor projects.

Can I vary speed smoothly?

Yes, PWM provides precise and smooth speed control.

Is it cost-effective?

Yes, uses readily available components for reliable performance.

Rojony Khatun

Rojony Khatun

CalculatorToolsProject

Rojony Khatun is the creator of a free online tools website designed to simplify everyday and engineering-related calculations for students, professionals, and hobbyists. The platform offers a wide variety of basic and advanced calculators across key categories, including Electrical Calculators, Electronic Calculators, and Time & Date Calculators, helping users solve problems quickly and accurately.