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Automatic 12V Fan Speed Controller | Fan speed controller circuit

12V DC fan speed controller for using in different electronic equipment like power amplifier for cooling. The fan speed is controlled based.
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Automatic 12V Fan Speed Controller | Fan speed controller circuit

12v dc fan speed controller - Electronic Project


It is an automatic 12V DC fan speed controller for use in different electronic equipment like power supply amplifiers for cooling. The fan the speed is controlled based on the temperature. The temperature is detected by using a thermistor. A thermistor is a passive sensor. Its resistance varies based on the temperature. It is two types -ve and +ve type. In the -ve type, the resistance decreases with increasing temperature and for the +ve type, the resistance increases with increasing temperature. Here the speed is controlled in 4 steps. I design it to use in my power supply amplifier to remove the heat from the heat sink very quickly. By using this fan I reduce the heat sink of the size. So, it is a very efficient and intelligent circuit diagram for equipment cooling.

The modulation is a process of varying the parameter of a carrier signal in accordance with the instantaneous value of the message of the signal. A modulation technique is used to encode the message into a pulsing signal. The term duty cycle describes the proportion of ‘on’ time to the regular interval or ‘period’ of time; a low duty cycle corresponds to a low power supply because the power supply is off most of the time. The 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 supply.

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

Diagram of Automatic 12V Fan Speed Controller Circuit:

12v dc fan speed controller

Hardware Required for this Project:

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Working Principle of 12 DC FAN Speed Regulator Circuit:

Here the circuit diagram works based on the op-amp IC LM324. It is a quad op-amp IC. Here it is wired as the comparator for comparing the input voltages. That is we detect the temperature by comparing the voltage. The thermistor (-ve type) is connected as a potential divider thus its voltage is varied with respect to the temperature variation. Here a stable reference voltage is provided by the 9.2V zener diode circuit. The diode of the reference is connected to the inverting input via different potential dividers to create different voltages at each comparator input. Thus by this arrangement, we compare the thermistor of the voltage in 4 different stages. The required output is the -ve output of the voltage. The -ve is obtained when the op-amp inverting terminal voltage is greater than the non-inverting voltage. The diodes are used to prevent the +ve voltages from op-amp otherwise the op-amp output will short-circuited. Each output is connected to a common transistor via different resistors. The resistors are used to limit the base current flow. The 390K base of the resistor is used to avoid false ON of the transistor. The three- capacitors are used to stabilize the voltages at the capacitor-connected points. This is the circuit explanation.

The images on the right side are the completed circuit in a common PCB. The thermistor used here is a -ve type. Thus at room temperature, the resistance is very high so the potential divider voltage is near Vcc (12V). The reference of the voltage 9.2V is divided into different sub voltages and each is connected to each op-amp the higher voltage is to the top op-amp or the lower is to the bottom op-amp. So at room temperature, all op-amps non-inverting terminal voltage is higher than the inverting terminal. Thus the transistor base is at high. Thus the fan is OFF. When the temperature increases, the thermistor diverts the voltage decreases. At a point, the top op-amp non-inverting voltage drops below its inverting of the voltage. So it produces a -ve output and the transistor gets ON and thus the fan gets ON. In further increasing the temperature all the op-amps activated one by one. At last, all the op-amp is activated and produces a maximum transistor base current and the fan gets its maximum speed. This is the working of this circuit.

The output of the multivibrator is fed to IRF 540 of the MOSFET. The fan is connected to the positive terminal of the battery or drain (D) of MOSFET T1. The Capacitor C1 is connected in parallel to the fan to stabilize its speed. Free-wheeling diode D1 protects the motor from back emf. A fuse is included for protection. Potmeter VR1 is used to change the duty of the cycle of the multivibrator and hence the speed of the fan. If you feel that the low/high level of the fan speed is not sufficient, increase/decrease the value of C2 (0.47 µF) to reduce/increase the speed of the fan. Assemble the circuit diagram on a general-purpose PCB or enclose it in a suitable cabinet. Fix the pot meter at the front side of the case, so that you can easily change the speed of the fan.

Connect the battery to the fan using wires with suitable current flow-carrying capacities. Use red wire for the positive terminal or black wire for the negative terminal. The advent of autonomous vehicles marks a significant milestone in technological advancement, bringing what was once mere speculation into reality. These self-driving cars achieve of remarkable levels of autonomy by integrating a suite of sensory technologies, including cameras, radar, and LiDAR. LiDAR, in particular, stands out for its use of light waves to measure distances, functioning like radar but with laser diodes or advanced photodiodes (APDs). However, this innovation brings a complex engineering challenge: developing a high-voltage power supply for the APD sensor, which is essential for its operation or must comply with stringent automotive standards, including cost-effectiveness and electromagnetic compatibility (EMC) regulations.

The reference design for LiDAR application from Monolithic Power Supply Systems employs the MPQ3910A to manage a boost converter operating in Discontinuous Conduction Mode (DCM). Doing so addresses the challenges of the LiDAR systems that operate at highly high-duty cycles, using cost-effective and compact components. The design cleverly doubles the boost of the voltage using a charge pump, enabling it to generate over 350V of output. This is achieved while utilizing semiconductors rated for lower voltages, which are smaller or less expensive and offer superior performance compared to the higher voltage of the alternatives.

Frequently Asked Questions

What is the principle of fan speed control?

A fan speed controller controls the voltage across the fan or therefore indirectly controls its speed. A fan speed regulator actually measures or regulates the speed of the fan using its tachometer.

What are the advantages of a fan controller?

With automated fan control, you no longer need to disrupt your workflow to adjust the speed or direction of your fans. Automating the fan speed saves time or maintains a consistently comfortable environment. You will be able to set the desired temperature or forget about it.

How does a DC fan controller work?

DC voltage control is the method to vary DC fan speed and this could be implemented by incorporating resistances in the supply wire. The voltage drop across the series resistor reduces the voltage reaching the fan supply pin, automatically slowing the speed of the fan.

Why control fan speed?

Speed control—one way to answer some of these objections to the use of a fan—could have these advantages: running a fan slower reduces the noise it emits, running a fan slower could reduce the power supply it consumes, and running a fan slower increases its reliability and lifetime.

What is the speed of a fan?

Speeds vary significantly, but most high-speed ceiling fans of the spin anywhere from 200 RPM (revolutions per minute) to around 380 RPM. In general, smaller fans spin faster, or larger fans rotate slightly slower as they increase in size.

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