Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [fan]

A device that produces air movement by way of blades or surfaces attached to a rotating motor.

490 questions
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Fan and heatsink - suck or blow?

This question covered it for enclosures. However, from the point of view of the fan attached to a heatsink does it matter whether air is blown through the fins, or sucked through the fins. In other words, is the pattern of airflow different enough…
Dirk Bruere
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Fan speed switch: why OFF :: HIGH :: MED :: LOW?

Many AC fans, including inexpensive floor models, have a rotary speed control which rotates from OFF to HIGH to MED to LOW. Since the switch does not rotate 360°, you have to rotate it backwards to shut it off. This has always slightly annoyed me,…
RichF
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How to interpret the output of a 3-pin computer fan speed sensor?

I have a 3-pin 12 V computer fan and I want to interpret its speed sensor output. At the yellow wire I get something that looks like pulse-with modulation. How would I interpret the output without actually connecting the fan to a computer?
AndrejaKo
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How do ceiling fan controllers work?

There are some devices that look like ordinary light dimmers, but are sold expressly for ceiling fan speed control. For example: Lutron Diva Quiet 3-speed control. Unlike an ordinary dimmer, this has a three-position switch for low, medium, and high…
Phil Frost
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Fans: suck or blow?

For a fan, should air be sucked in, or should it blow air out? I'm talking about an enclosure mounted fan.
Thomas O
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What's needed to put a PC fan into reverse?

I've got a PC fan here (I've peeled off a sticker). And although this one doesn't come with the usual 3 or 4 wire connectors, it has enough electronics in it to only operate when power + is on red, and - is black but/and it won't operate when power…
isync
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Detecting stalled AC fan in high-temperature system

The problem: AC 230 VAC fans in a system rated to 100 °C need to be monitored for failure. There is no third wire, just the L and N leads. None of the potential solutions seem good. For example: Optical coupler of some kind Hall sensor near…
Dirk Bruere
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How do I eliminate PWM noise when driving a fan?

I'm driving a 12V 0.11A brushless DC fan with PWM using an MSP430Gxxxx --> TC427CPA FET driver --> BS170 N-FET. The fan is on the low side of the FET. Even with a duty cycle of 90% and a frequency of 10kHz, there's audible buzzing coming from the…
Vincent Van Den Berghe
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Reducing electrical noise induced from a small DC electrical fan

What's a canonical method for reducing / eliminating electrical noise induced in ADC from a small brushless DC fan? For reference below, I'm also using this wall-wart and this 5V linear regulator. My baseline system looks like this: I have some…
vicatcu
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Part number for this Molex 4 pin wire-to-board connector (or similar: Foxconn, Wieson, Tyco, etc)

I'm having a really hard time finding the correct PN for a 4 pin header, used with PWM fans. The header I'm looking for is a 4 pin one, similar to the Molex 47053-1000, but a right angle one. I've already spent a couple of hours on Digikey and the…
avc
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AC fan speed control

I use this fan to cool my room, but sometimes it is too fast and I have to frequenctly turn it on and off to keep normal temperature. Maybe it is possible to reduce the speed by connecting a resistor in series or using a variac. The fan uses some…
Pentium100
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What is this Lenovo 4-pin fan header?

I have a Lenovo p620 machine and I'm trying to swap out the terribly loud fans with Noctua PWM fans. The problem is the 2 chassis fans are using a weird 4-pin connector where the ridges are on the far sides. See pictures. What are these called and…
Chris Smith
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How do I make an opamp comparator work in schmitt-trigger mode?

I want to control a small 12V case fan. I will set values of R1, R2 and R3 so that the fan will work above temperatures 40oC. I understand that in these kind of systems, there will be an indecisive region in which the comparator output will be fast…
hkBattousai
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Using 1N4148 As A Temperature Sensor

Can I know which component senses heat or acts as heat sensor in the following circuit? In the given diagram, it is said that the 1N4148 diode acts as the sensor. But basically it is a zener diode and I don't think that it is able to sense…
Kavi Pritha
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Fan at full speed on PC - Is there anything I can do to slow it down?

The internal sensor for the motherboard is giving out an invalid value for the temperature, causing the fan to go on full. The computer is exactly 10 days out of warranty. It's a 4 Pin 12v PWM fan. Is there anything I can do to manually control the…
JohnnyVegas
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