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Fan Speed Controller

Elvis Elvis

A fan speed controller is necessary to minimize heat in computers and other electronic gadgets without creating noise. These days, people prefer those products that the market is making smaller & smaller but big on computing power and features. These electronic goods generally generate high temperature. Usually cooling fans are used to minimize the heat. Nevertheless, the cooling fans too have their drawbacks. They create noise and consume lot of power. Therefore, it becomes necessary to remove the heat quietly and in a cost effective way.

There are some other ways to remove heat. These include heat sinks and heat pipes. However, they are quite expensive and inefficient. Active cooling remains the best alternative. A fan in the system can remove the heat by generating airflow around the chassis and the heat-generating components. However, to reduce noise and power consumption, it is necessary to use fan speed controllers.

The fan speed controllers have a three-way function-

1. It reduces the noise in the system.

2. It reduces the power consumption.

3. It increases the reliability and lifetime of the system.

Fan Speed Controller

There are several types of fans. The fan speed controllers may vary depending on the fan type. Those fan types include:

1. 2-wire fans:2-wire fans have power and ground terminals.

2. 3-wire fans:3-wire fans have a tachometric (“tach”) output in addition to power and ground. It provides a signal with frequency proportional to speed.

3. 4-wire fans:4-wire fans on the other hand have power, ground, a tachometric output and a PWM-drive input. PWM adjusts the level of power applied to the motor. Here, it uses the relative width of pulses in a sequence of on-off pulses.

There is a number of fan speed controlling methods. These include:

1. No fan control: The simplest fan speed controlling method is to shun its use totally. A fan running constantly, consumes lot of power and its lifetime gets shorter.

2. On/off control: This is another simple method where you use a switch to control the fan. When you need cooling, you just need to switch on the fan and switch it off when you do not need it. In certain devices, you have the facility to programmer the heat limit according to necessity. The switch gets on and off automatically according to the need. However, the disadvantage with this type of fan speed controller is that, the switching off and on of the fan becomes very distracting.

3. Linear control: This is a type of fan speed controller, where we control the power supply to controls the speed of the fan. The voltage is reduced for lower speed and increased for higher speed level. The advantage with linear control is that it is considerably quiet. Nonetheless, the fan requires a certain amount of voltage to run. There is a chance of malfunctioning due to controlling of the voltage. The circuit is also inefficient, though expensive. Further, there is a problem of loss of power in the amplifier circuit.

4. Pulse Width Modulation (PWM) Control: In this technique, the power supply is either maximum or zero. So the fan is either on or off in this type of fan speed controller. This controlling technique is simple, efficient and cost effective. However, in low frequency PWM, the drive signal chops the tach information, as power supply is not constant. A technique called pulse stretching is applied to retrieve the tach information. Noise is another problem with low frequency PWM. High frequency PWM does not have these problems. However, a four-wire fan is necessary to apply this technique.