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How do you control the speed of a DC fan?
DC voltage control is the method to vary DC fan speed and this can 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.
How can I make my 12v fan run slower?
2 Answers
- Add a potentiometer in series with the power cable. This would allow you to change the speed quite easily.
- control the fan using pwm. This could be with a microcontroller or just a 555 oscillator through a transistor.
- Have a constant current circuit.
How does a voltage divider work on a fan?
Applying a direct voltage to the adjust leg will achieve the same results as varying the resistance. As you will notice in Figure 2, the resistors tied to the adjust leg create a voltage divider. By varying the external resistor, a voltage divider supplies the adjust leg with a varying voltage.
What kind of thermistor is used for a DC fan?
Here a 4.7K NTC Thermistor is used.IC uA 741 is used as a voltage comparator to switch on the DC fan. Its INV input (pin2) gets an adjustable voltage through VR while its Non-INV (pin3) input gets voltage through a potential divider comprising R1 and the Thermistor. Thus the voltage at pin3 depends on the conductivity of the Thermister.
What is the formula for a voltage divider calculator?
Voltage Divider Calculator. A voltage divider circuit is a very common circuit that takes a higher voltage and converts it to a lower one by using a pair of resistors. The formula for calculating the output voltage is based on Ohms Law and is shown below. R 1 is the resistance of the 1st resistor, measured in Ohms (Ω).
How is the resistance of a brushless DC fan calculated?
Brushless DC fans contain active circuitry — a DVM or multimeter cannot measure the proper resistance of such due to the low voltage applied. However, the resistance can be calculated from the load current measurement at rated voltage. Is it possible to alter the circuit so that we can use a 10k (or some other value) ohm thermistor in the circuit?