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  Simple 12V DC Fan Speed Controller Using IC 555

Last Updated on January 10, 2018 by Admin 2 Comments

In this post we are going to construct a circuit to control the speed of 12V DC fan which is commercially available to run on 12V Solar panels and Batteries.

The utilization of DC fan become common where access to electricity is not established the area or where power cuts are pretty common or even on old model cars. In this situation battery powered fans come in handy. DC fans reasonably deliver air thrust as table top fans which operate at 230V/110VAC current.

If you want to save some power to by reducing the speed and prolong the battery life or if you want to adjust fan speed to your comfort, we need a fan speed controller which must not generate heat while throttling the speed.

The simplest way to throttle speed is to connect a variable resistor in series with fan, right? Wrong!

We can control speed by using a simple variable resistor, this method is very simple and very much inexpensive method, but why we do not prefer it?

Our goal for battery operated devices is to save energy as possible. The drawback of using variable resistor method is the excess energy is converted to heat; this will reduce battery life drastically.

  Simple 12V DC Fan Speed Controller Using IC 555

To overcome this problem we are going for PWM which reduce power to the motor by switching the power on and off rapidly. The duty cycle or width of the on and off time determine the speed of fan, but the frequency remains constant.

Here is a very simple PWM generator using IC555, by varying the variable resistor, the pulse width can be changed. This is fed to MOSFET which is capable of handling higher current for the fan, the diode across fan suppress high voltage spike while turning the fan on/off.

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About Admin

Hey friends, Thanks a bunch for stopping by this site! I am an engineer with a Bachelor of Engineering in Electronics and Telecommunication. One of my passions is gathering information from all sorts of electronics books and tutorials. I then take that information and compile it into a language that is super easy to understand. My goal is to make those complex electronics circuit concepts and technical terms much more accessible for all the new and budding electronics engineers out there. I can also design customized circuit diagrams as required by the users.
If you have any questions related to this field, please do not hesitate to drop a comment! I am always here and ready to help you out with any queries you might have. I cannot wait to hear from you!

Reader Interactions

Comments

  1. Chandana Suranjith says

    February 6, 2022 at 10:22 pm

    Hi,

    Can i know the exact output voltage when 100k VR is 0 ? Because almost every regulator circuit which uses LM317 & IRF540 has a maximum output of 11V (Input is 12V).

    Reply
    • admin says

      February 10, 2022 at 5:24 pm

      Hi, the output will be from 0 to 12V or from minimum to maximum. I have tested it with oscilloscope.

      Reply

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