DC Motor DC Fan Speed Controller circuit

DC FAN Speed Regulator Circuit

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DC FAN Speed Regulator Circuit

DC FAN Motor Speed Controller Regulator Circuit Works ON Principle of Pulse Width Modulation (PWM) technique , By Using This Technique Controlling Of DC Motor Speed is very Smoothly And Noise Free.

Introduction Of  PWM

The modulation is a process of varying the parameter of a carrier signal in accordance with the instantaneous value of the message signal. Modulation technique is used to encode the message into a pulsing signal.

A Pulse Width Modulation (PWM) Signal is a method for generating an analog signal using a digital source.  A PWM signal consists of two main components that define its behavior- a duty cycle and a frequency. The duty cycle describes the amount of time the signal is in a high (on) state as a percentage of the total time of it takes to complete one cycle. The frequency determines how fast the PWM completes a cycle (i.e. 1000 Hz would be 1000 cycles per second), and therefore how fast it switches between high and low states. By cycling a digital signal off and on at a fast enough rate, and with a certain duty cycle, the output will appear to behave like a constant voltage analog signal when providing power to devices.

• The term duty cycle describes the proportion of ‘on’ time to the regular interval or ‘period’ of time; a low duty cycle corresponds to low power, because the power is off for most of the time. Duty cycle is expressed in percent, 100% being fully on.

The PWM method is a great method to control the amount of power delivered to a load without initiating the waste power.

pulse width modulation theory

  Average Output Voltage is Proportional to ON Time Of Duty Cycle.

PWM signals are used for a wide variety of control applications. Their main use is for controlling DC motors but it can also be used to control valves, pumps, hydraulics, and other mechanical parts. The frequency that the PWM signal needs to be set at will be dependent on the application and the response time of the system that is being powered. Below are a few applications and some typical minimum PWM frequencies required:

  • Heating elements or systems with slow response times: 10-100 Hz or higher
  • DC electric motors: 5-10 kHz or higher
  • Power supplies or audio amplifiers: 20-200 kHz or higher

The following are the advantages and disadvantages of controlling the speed of a DC motor with PWM are


  • The consumption of power to the motor is very less
  • Due to heat there is a less amount of energy is decreased
  • It will allow the fine motor control
  • The efficiency is up to 90%

Disadvantages                      Must Read What is 555 Tmer

  • The pulse width modulation circuit is complex
  • Radio frequency interface
  • Voltage spikes

Here is Some circuit diagram of DC fan Regulator Using PWM Method.

By This Method Smoothly Controlled The Speed Of DC Motor At Negligible Noise

BY using This Circuit You can control the speed of DC Fan by tuning the (Potentiometer) volume control variable resistance. These circuits are based on 555 Timer .

use at least 470K POT ( Vol control potentiometer) to set the required speed


 Don’t Forget To Read Remote Controlled ON OFF Switch circuit With Video 

circuit diagram of DC Fan Speed controller.(Tested on 12v Motor)

speed control of dc motor using pwm using 555 timer

Circuit 2.

DC motor controller using 555 timer and MOSFET IRFZ540

12v dc fan speed control circuit

Also Read–  How to Make LED Indicator For 220v AC 

Also Read 12V DC To 220V AC Homemade Inverter Circuit

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4 thoughts on “DC FAN Speed Regulator Circuit”

  1. I built circuit 1, but the motor runs at full speed regardless of VR1 setting. I can’t find any errors in my wiring, so I’m puzzled as to what is going on. Can you suggest what I should check? I have an oscilloscope that I can use as well as the usual multimeter.
    Many thanks in advance

  2. The diode D2 in circuit 1 is the wrong way around! The cathode should be connected to pin 7 of the 555. As the circuit is drawn now the motor wil run at full speed with no control.

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