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    I need to make a fan controller.

    So here's the deal, I put some new fans in my server to replaced acouple of near dead/dead fans. The new fans are LOUD! but they push alot of air.

    Anyways I have 4 of these babies pushing air pass my raid array to keep those drives ice cold.

    The fan itself takes 12v 0.34 amps or 4.08 watts.

    I can't find anything that meets my needs.

    I'm looking for a master control, not individual control. Something like APEVIA FC-01 Multi Fan Speed Controller but can handle more amperage, 1.2a is low.

    I was thinking about building my own, but I'm not an electronics engineer so I'm not sure where to begin.

    Any ideas?

    what would I need?

    #2
    Re: I need to make a fan controller.

    Originally posted by Mad_Professor View Post
    So here's the deal, I put some new fans in my server to replaced acouple of near dead/dead fans. The new fans are LOUD! but they push alot of air.

    Anyways I have 4 of these babies pushing air pass my raid array to keep those drives ice cold.

    The fan itself takes 12v 0.34 amps or 4.08 watts.

    I can't find anything that meets my needs.

    I'm looking for a master control, not individual control. Something like APEVIA FC-01 Multi Fan Speed Controller but can handle more amperage, 1.2a is low.

    I was thinking about building my own, but I'm not an electronics engineer so I'm not sure where to begin.

    Any ideas?

    what would I need?
    I am not an eletrical engineer... yet (3 more years of school), but I have an idea:

    you could maybe use some sort of a thermistor circuit? thermistors decrease resistance as temperature goes up... so put a thermistor and a pot in series with the fans and with careful part choices and tuning of the pot you have a temp control circuit. for optimal control, put the thermistor at the exhaust of the air system.
    sigpic

    (Insert witty quote here)

    Comment


      #3
      Re: I need to make a fan controller.

      ^
      That does have on major problem - drawing any more than 4W through a thermistor will cause it to heat up, so it will just run the fan at almost full speed.
      I love putting bad caps and flat batteries in fire and watching them explode!!

      No wonder it doesn't work! You installed the jumper wires backwards

      Main PC: Core i7 3770K 3.5GHz, Gigabyte GA-Z77M-D3H-MVP, 8GB Kingston HyperX DDR3 1600, 240GB Intel 335 Series SSD, 750GB WD HDD, Sony Optiarc DVD RW, Palit nVidia GTX660 Ti, CoolerMaster N200 Case, Delta DPS-600MB 600W PSU, Hauppauge TV Tuner, Windows 7 Home Premium

      Office PC: HP ProLiant ML150 G3, 2x Xeon E5335 2GHz, 4GB DDR2 RAM, 120GB Intel 530 SSD, 2x 250GB HDD, 2x 450GB 15K SAS HDD in RAID 1, 1x 2TB HDD, nVidia 8400GS, Delta DPS-650BB 650W PSU, Windows 7 Pro

      Comment


        #4
        Re: I need to make a fan controller.

        I don't know if I want thermal control. Call me old fashion but I like manual control. as c_hegge said the thermistor will heat up.

        Anyways I'm kicking around the net looking for designs and ideas..

        I've found one over at overclocker.com

        http://www.overclockers.com/forums/s...d.php?t=677283

        also

        http://www.overclockers.com/forums/s...d.php?t=646148




        1 LT1083CP or LM1084IT-ADJ
        2 Capacitor, electrolytic 330uf 25V
        1 Capacitor, electrolytic 1000uf 16V
        1 resistor 10 ohms
        1 resistor 3600 ohms
        1 resistor 1200 ohms
        1 10K POT
        2 1N4002 diode

        Comment


          #5
          Re: I need to make a fan controller.

          There are a huge number of different ways you can create your own fan controller. I will list the ways I can remember off the top of my head.

          1) Use a potentiometer as a simple variable resistor. The trouble with this is that you want to control multiple fans with a single control source. Therefore the potentiometer would have to be pretty beefy to withstand 4W of power. They probably exist but cost a fair bit.

          2) Use diodes in series. Each diode you place in series with the fan will drop around 1.2-1.7V. I have seen people online hook up diodes through a 'selection' (forgot the proper name) rotary switch. For every click on the rotary switch, another diode goes in series with the fan, therefore reducing the voltage at the fan. This may suffer from the same fate as the potentiometer. The diodes you use would have to be reasonably beefy. However they do exist and won't cost much.

          3) I have seen people online build their own analog PWM circuit. You would have a low powered signal to adjust the duty cycle of the PWM circuit. The switching transistors you use for the circuit will need to be able to withstand 4W of power (pretty easy to come by).

          4) I have seen people online build their own linear controller circuit. I can not remember the details of this approach. However it is an analog circuit where a low powered signal (which can be controlled by a knob) can adjust the output voltage. Disadvantage is heat. To reduce the voltage in a linear circuit, you need to 'absorb' the extra energy which normally means dissipating it as heat.

          5) My favourite solution is to use a simple microcontroller based solution. Nearly all microcontrollers have a number of PWM outputs and a variety of different inputs (digital and analog). One would normally program a microcontroller using C. Essentially you would connect your inputs to the microcontroller. Lets just say something liked a switch or a potentiometer and you connect your fans to the output. The output circuit (PWM signal) will need a transistor based switching circuit because the output signal from a microcontroller only carries a tiny amount of current. You need to amplify the signal using a transistor circuit so that it can handle the power output you wish to use. Transistors that can handle a few amps are cheap and easy to come by. This is my favourite idea because I love programming, it is simple and it gives you ultimate flexibility. For example, if in the future you may want to have a temperature controlled fan controller. Just hook up thermistors, thermocouples, temperature measuring IC's or any other kind of temperature dependant sensor to the microcontroller. Reprogram the microcontroller and you have exactly what you want. Add to this, Arduino and Arduino clones are pretty cheap now, it is reasonably cost effective solution as well (most likely will still cost more than the other solutions I mentioned thou).
          Last edited by shadow; 01-31-2012, 08:44 PM.

          Comment


            #6
            Re: I need to make a fan controller.

            If you are interested in building a microcontroller based circuit, I can give you a schematic and possibly even a stripboard design. I decided to create a temperature controlled fan controller with both automatic and manual modes (manual controlling each fan with a small potentiometer). Along with this I was thinking about potentially connecting a small monochrome LCD to it. However I never got around to soldering up the circuit and writing the software. I changed PC's since I designed the device and my new PC is reasonably quiet. I still think about soldering that circuit from time to time for fun and making my PC even more quiet. I would still need to purchase the 1-Wire temperature sensors, however they can be added later. I could work on the manual control first.

            I also have a relatively large collection of circuits and designs archived somewhere as well. If you are interested I can try to dig them up.

            Originally posted by Mad_Professor View Post
            I don't know if I want thermal control. Call me old fashion but I like manual control. as c_hegge said the thermistor will heat up.

            Anyways I'm kicking around the net looking for designs and ideas..

            I've found one over at overclocker.com

            http://www.overclockers.com/forums/s...d.php?t=677283

            also

            http://www.overclockers.com/forums/s...d.php?t=646148




            1 LT1083CP or LM1084IT-ADJ
            2 Capacitor, electrolytic 330uf 25V
            1 Capacitor, electrolytic 1000uf 16V
            1 resistor 10 ohms
            1 resistor 3600 ohms
            1 resistor 1200 ohms
            1 10K POT
            2 1N4002 diode

            Comment


              #7
              Re: I need to make a fan controller.

              Originally posted by shadow View Post
              4) I have seen people online build their own linear controller circuit. I can not remember the details of this approach. However it is an analog circuit where a low powered signal (which can be controlled by a knob) can adjust the output voltage. Disadvantage is heat. To reduce the voltage in a linear circuit, you need to 'absorb' the extra energy which normally means dissipating it as heat.
              The schematic he posted is a linear regulator. While i would use PWM, it's not worth the extra trouble for just 4 fans. If i were Mad_Professor now, i'd go ahead and build that circuit, because it's gonna do its job just fine. Just remember to put a suitable heatsink on the LM1084.
              Originally posted by PeteS in CA
              Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
              A working TV? How boring!

              Comment


                #8
                Re: I need to make a fan controller.

                Do you want manual or automatic control?

                The fan controller in my computer uses a TC648B IC driving an IRF510 MOSFET. The fan speed changes automatically as the temperature changes. All you would have to do is build the application circuit in the TC64x datasheet (the TC64xB datasheet does not contain any application information). The resistors in the voltage divider on the IC's input need to be calculated based on the resistance of the thermistor being used at both the minimum and maximum desired temperatures.

                A 555 timer can be used as well if the temperature warning in the TC648 is not needed or if you want manual control of the fan. All of the parts needed to build a fan controller using a 555 timer can be purchased at Radio Shack.

                I didn't know that an LM1084 or LT3083 could handle 5A.
                Last edited by lti; 01-31-2012, 09:15 PM.

                Comment


                  #9
                  Re: I need to make a fan controller.

                  http://www.linear.com/samples/LT1084

                  Request samples, they'll send no questions asked. Max 2 of up to 5 different parts .. but don't be greedy.

                  I asked for two of LT1084 (5A) and 2 LT1083 (3A) and got them in about 2 weeks. No spam, no feedback requests, nothing.

                  You then need two decoupling capacitors and optionally two larger capacitors for smoothing, two resistors (or one resistor and one potentiometer) for voltage control and optionally a diode to block current from going back into the regulator (d2 in the schematic above)

                  Oh and you need a heatsink... watts lost in heat = (Vin - Vout) x I ... so a 0.34a fan @ 5v = (12-5)x 0.34 = 2.5 watts in heat that need to be dissipated.

                  Comment


                    #10
                    Re: I need to make a fan controller.

                    Originally posted by shadow View Post
                    There are a huge number of different ways you can create your own fan controller. I will list the ways I can remember off the top of my head.

                    1) Use a potentiometer as a simple variable resistor. The trouble with this is that you want to control multiple fans with a single control source. Therefore the potentiometer would have to be pretty beefy to withstand 4W of power. They probably exist but cost a fair bit.

                    2) Use diodes in series. Each diode you place in series with the fan will drop around 1.2-1.7V. I have seen people online hook up diodes through a 'selection' (forgot the proper name) rotary switch. For every click on the rotary switch, another diode goes in series with the fan, therefore reducing the voltage at the fan. This may suffer from the same fate as the potentiometer. The diodes you use would have to be reasonably beefy. However they do exist and won't cost much.

                    3) I have seen people online build their own analog PWM circuit. You would have a low powered signal to adjust the duty cycle of the PWM circuit. The switching transistors you use for the circuit will need to be able to withstand 4W of power (pretty easy to come by).

                    4) I have seen people online build their own linear controller circuit. I can not remember the details of this approach. However it is an analog circuit where a low powered signal (which can be controlled by a knob) can adjust the output voltage. Disadvantage is heat. To reduce the voltage in a linear circuit, you need to 'absorb' the extra energy which normally means dissipating it as heat.

                    5) My favourite solution is to use a simple microcontroller based solution. Nearly all microcontrollers have a number of PWM outputs and a variety of different inputs (digital and analog). One would normally program a microcontroller using C. Essentially you would connect your inputs to the microcontroller. Lets just say something liked a switch or a potentiometer and you connect your fans to the output. The output circuit (PWM signal) will need a transistor based switching circuit because the output signal from a microcontroller only carries a tiny amount of current. You need to amplify the signal using a transistor circuit so that it can handle the power output you wish to use. Transistors that can handle a few amps are cheap and easy to come by. This is my favourite idea because I love programming, it is simple and it gives you ultimate flexibility. For example, if in the future you may want to have a temperature controlled fan controller. Just hook up thermistors, thermocouples, temperature measuring IC's or any other kind of temperature dependant sensor to the microcontroller. Reprogram the microcontroller and you have exactly what you want. Add to this, Arduino and Arduino clones are pretty cheap now, it is reasonably cost effective solution as well (most likely will still cost more than the other solutions I mentioned thou).
                    I'm not a programmer so I would not be able to write C, but I could learn it in my own time. The other thing is I don't have a need for temperature control since the fans I want to control is all group together in-front of the hard-drives.

                    But how easy is it to do a microcontroller? could I have several lower amp transistors to power four 3 pin connections and one molex to reduce heat emmision?


                    Originally posted by shadow View Post
                    If you are interested in building a microcontroller based circuit, I can give you a schematic and possibly even a stripboard design. I decided to create a temperature controlled fan controller with both automatic and manual modes (manual controlling each fan with a small potentiometer). Along with this I was thinking about potentially connecting a small monochrome LCD to it. However I never got around to soldering up the circuit and writing the software. I changed PC's since I designed the device and my new PC is reasonably quiet. I still think about soldering that circuit from time to time for fun and making my PC even more quiet. I would still need to purchase the 1-Wire temperature sensors, however they can be added later. I could work on the manual control first.

                    I also have a relatively large collection of circuits and designs archived somewhere as well. If you are interested I can try to dig them up.
                    I'm still open for the idea, but have no need for temperature control.
                    how long would it take to build?

                    I can hear my server from my kitchen which is like 30 feet away.

                    Originally posted by Th3_uN1Qu3 View Post
                    The schematic he posted is a linear regulator. While i would use PWM, it's not worth the extra trouble for just 4 fans. If i were Mad_Professor now, i'd go ahead and build that circuit, because it's gonna do its job just fine. Just remember to put a suitable heatsink on the LM1084.
                    I don't have PWM fans.
                    How big of a heatsink and on what?

                    Originally posted by lti View Post
                    Do you want manual or automatic control?

                    The fan controller in my computer uses a TC648B IC driving an IRF510 MOSFET. The fan speed changes automatically as the temperature changes. All you would have to do is build the application circuit in the TC64x datasheet (the TC64xB datasheet does not contain any application information). The resistors in the voltage divider on the IC's input need to be calculated based on the resistance of the thermistor being used at both the minimum and maximum desired temperatures.

                    A 555 timer can be used as well if the temperature warning in the TC648 is not needed or if you want manual control of the fan. All of the parts needed to build a fan controller using a 555 timer can be purchased at Radio Shack.

                    I didn't know that an LM1084 or LT3083 could handle 5A.
                    same as above about temperature control. I've thought about building one from a 555 since I was successful when I did my pwm based fan controller for my PS3 mod.


                    Originally posted by mariushm View Post
                    http://www.linear.com/samples/LT1084

                    Request samples, they'll send no questions asked. Max 2 of up to 5 different parts .. but don't be greedy.

                    I asked for two of LT1084 (5A) and 2 LT1083 (3A) and got them in about 2 weeks. No spam, no feedback requests, nothing.

                    You then need two decoupling capacitors and optionally two larger capacitors for smoothing, two resistors (or one resistor and one potentiometer) for voltage control and optionally a diode to block current from going back into the regulator (d2 in the schematic above)

                    Oh and you need a heatsink... watts lost in heat = (Vin - Vout) x I ... so a 0.34a fan @ 5v = (12-5)x 0.34 = 2.5 watts in heat that need to be dissipated.
                    samples awesome! how clever. I save $3 if I do this.

                    Well I'll be power 4 of the same type plus one more at 0.22a.





                    The only other issue is how do I seal the unit from the case if I slap a heatsink on the heat producing component; wouldn't that ground it?

                    Comment


                      #11
                      Re: I need to make a fan controller.

                      Most devices in TO220 case have the metal side connecting to the heatsink as ground.
                      So the heatsink could touch the metal case of your computer and you won't have problems (but double check that the linear voltage regulator you select has ground on that metal tab)

                      It all depends on the final design of your device... for example you could make it like this one, which has small heatsinks on each voltage regulator:

                      http://www.newegg.com/Product/Produc...82E16811995016

                      Click on the pictures, you can see it quite clearly.... though if you plan to power four fans from a single regulator, you'll need a thicker and larger heatsink
                      Last edited by mariushm; 02-01-2012, 01:47 PM.

                      Comment


                        #12
                        Re: I need to make a fan controller.

                        I have a cheap and dirty way to do it:

                        Materials:
                        )Fan
                        )3 way standard household light switch
                        )Time
                        )My diagram
                        )Power supply
                        )Electric wire (I use 22AWG)

                        Step 1:
                        Cut 2 pieces of wire and strip both ends. Attach the wires like shown in Pic #1.
                        NOTE: Don't use the green screw, otherwise it won't work!
                        Step 2:
                        Attach the negative (black) wire from the fan into a ground connection on the power supply.
                        Step 3:
                        Connect the other two disconnected wires in to the psu, one to +5V (red) and one to +12V (yellow). NOTE: It doesn't matter which one you connect; the only difference is that the way you flip it to get different speeds.
                        Step 4:
                        Mount the fan and switch where you want them to be.
                        Step 5:
                        Plug in and turn on your PC. The fan should start spinning. Flip the switch. If it spins either slower or faster, then success! If your PC will not turn on (no power), double check your wiring and go for it again.
                        Step 6:
                        You can get creative with this, example: finding a unique way to mount the switch. I, personally, would hot glue it to one of the open expansion brackets and cover up the holes with electric tape.

                        All the above made purely by me!
                        Attached Files

                        Comment


                          #13
                          Re: I need to make a fan controller.

                          Originally posted by Mad_Professor View Post
                          I'm not a programmer so I would not be able to write C, but I could learn it in my own time. The other thing is I don't have a need for temperature control since the fans I want to control is all group together in-front of the hard-drives.
                          Fair enough, it is relatively simple to write a program like you wish (without fancy things like temperature control and LCD's and the like). If you look at the Arduino compatible microcontrollers, you do not need to program them in C, it is encouraged to use their own language which is a higher level form of C along with all of their hardware libraries. In fact their language gets parsed to C and then a C compiler compiles it to a hex file which is uploaded to the microcontroller. It is true that their libraries are heavy in comparison to writing your own C code, however something like this will not create any issues and the libraries make it super simple to do things like read a value from a potentiometer and output a PWM signal.

                          Originally posted by Mad_Professor View Post
                          I'm still open for the idea, but have no need for temperature control.
                          how long would it take to build?
                          Circuits for a microcontroller based fan controller is very simple (even more simple than the analog circuits you linked). So they would not take much time at all to build.

                          Originally posted by Mad_Professor View Post
                          Could I have several lower amp transistors to power four 3 pin connections and one molex to reduce heat emmision?
                          Yes you can easily achieve this using a microcontroller based circuit.

                          What I would do is connect each fan to a separate PWM channel on the microcontroller. Therefore in theory each fan could be controlled independently and uses lower power transistors. When you write your program, one would write something like; 'When the value of the potentiometer changes, change the PWM duty cycle for PWM channel 1 to 4'. This is just an example, however it is practical and easy to achieve. I believe it is also the most flexible. In the future one could easily change the setup if desired. For example if in the future you wanted to control each fan independently using separate potentiometers. It would be possible to achieve by just adding a few potentiometers, connect them to the microcontroller and change the program slightly so that each PWM channel is controlled by a separate potentiometer.

                          Originally posted by Mad_Professor View Post
                          I don't have PWM fans.
                          How big of a heatsink and on what?
                          You can send a PWM signal to a non PWM fan. From memory I have heard that some fan's may not like certain duty cycles so they groan a bit. However increasing or decreasing the speed a bit should fix that. I believe nearly all commercial fan controllers make use of PWM to control the speed of the fans.

                          Just to clarify what a PWM signal is. PWM is the process of rapidly switching the power to a device on and off very rapidly. On a 12V fan, this means switching between 12V and 0V very rapidly. The ratio between the time that the fan is turned on to the time that the fan is turned off is the duty cycle. For example, a 50% duty cycle implies that in one PWM period, the fan is turned on half the time and turned off half the time. The average power delivered to the fan is 50% (or 6V). The fan will run as if it were run at 6V, however this is achieved by rapidly switching between full power and no power.

                          The linear circuit which you have linked works differently. I can not go into the full electronics scheme of things without analysing the circuit again. However the idea is that when the potentiometer is set at 50%, the actual output voltage will be 6V and the 'excess' 6V worth of power is dissipated as heat (most likely through the transistors). It does not switch between full power and no power to achieve an average voltage or an average power output.

                          On a PWM circuit, it is unlikely you will need heatsinks at all. However on a linear circuit, you will require a heatsink on the main transistor in the circuit. It will heat up to 'absorb' the wasted power.




                          I have tried looking for the circuits I had of various fan controllers. However I have hosed them at some stage. I had hard copies of some of them, however I threw them out a few months ago in a big cleanup. I can not seem to find the website they were hosted on anymore.

                          However I am happy to provide a schematic to a simple microcontroller based fan controller if you wish (without the fancy temperature control or LCD etc.)
                          Last edited by shadow; 02-02-2012, 03:32 PM. Reason: Spelling and Grammar

                          Comment


                            #14
                            Re: I need to make a fan controller.

                            Originally posted by shadow View Post
                            Fair enough, it is relatively simple to write a program like you wish (without fancy things like temperature control and LCD's and the like). If you look at the Arduino compatible microcontrollers, you do not need to program them in C, it is encouraged to use their own language which is a higher level form of C along with all of their hardware libraries. In fact their language gets parsed to C and then a C compiler compiles it to a hex file which is uploaded to the microcontroller. It is true that their libraries are heavy in comparison to writing your own C code, however something like this will not create any issues and the libraries make it super simple to do things like read a value from a potentiometer and output a PWM signal.



                            Circuits for a microcontroller based fan controller is very simple (even more simple than the analog circuits you linked). So they would not take much time at all to build.



                            Yes you can easily achieve this using a microcontroller based circuit.

                            What I would do is connect each fan to a separate PWM channel on the microcontroller. Therefore in theory each fan could be controlled independently and uses lower power transistors. When you write your program, one would write something like; 'When the value of the potentiometer changes, change the PWM duty cycle for PWM channel 1 to 4'. This is just an example, however it is practical and easy to achieve. I believe it is also the most flexible. In the future one could easily change the setup if desired. For example if in the future you wanted to control each fan independently using separate potentiometers. It would be possible to achieve by just adding a few potentiometers, connect them to the microcontroller and change the program slightly so that each PWM channel is controlled by a separate potentiometer.



                            You can send a PWM signal to a non PWM fan. From memory I have heard that some fan's may not like certain duty cycles so they groan a bit. However increasing or decreasing the speed a bit should fix that. I believe nearly all commercial fan controllers make use of PWM to control the speed of the fans.

                            Just to clarify what a PWM signal is. PWM is the process of rapidly switching the power to a device on and off very rapidly. On a 12V fan, this means switching between 12V and 0V very rapidly. The ratio between the time that the fan is turned on to the time that the fan is turned off is the duty cycle. For example, a 50% duty cycle implies that in one PWM period, the fan is turned on half the time and turned off half the time. The average power delivered to the fan is 50% (or 6V). The fan will run as if it were run at 6V, however this is achieved by rapidly switching between full power and no power.

                            The linear circuit which you have linked works differently. I can not go into the full electronics scheme of things without analysing the circuit again. However the idea is that when the potentiometer is set at 50%, the actual output voltage will be 6V and the 'excess' 6V worth of power is dissipated as heat (most likely through the transistors). It does not switch between full power and no power to achieve an average voltage or an average power output.

                            On a PWM circuit, it is unlikely you will need heatsinks at all. However on a linear circuit, you will require a heatsink on the main transistor in the circuit. It will heat up to 'absorb' the wasted power.




                            I have tried looking for the circuits I had of various fan controllers. However I have hosed them at some stage. I had hard copies of some of them, however I threw them out a few months ago in a big cleanup. I can not seem to find the website they were hosted on anymore.

                            However I am happy to provide a schematic to a simple microcontroller based fan controller if you wish (without the fancy temperature control or LCD etc.)
                            Alright.. what would I need?

                            Part's list

                            How does one program a chip?

                            Cable? Interface module?

                            software requirements?

                            I need to power 5 fans at 0.34 amps via 12v using five 3-pin headers but I want to keep it compact and small. Less heat the better.

                            This is all new to me and I like learning new stuff.

                            Comment


                              #15
                              Re: I need to make a fan controller.

                              bump

                              Comment


                                #16
                                Re: I need to make a fan controller.

                                The 3 pin headers tell you the fans change their speed by altering the voltage ... you have 2 wires for power and one to tell the computer the speed.
                                So you can't use the PWM design with such fans.

                                You need to make a circuit that changes the voltage from 12v to anything between about 4v and 12v.
                                So you're left with two options:

                                1. use a switching dc-dc converter which will "chop" the input voltage and generate lower voltages without so much heat but requires a few more parts than the other solution (schottky diodes, inductors) and some relatively simple calculations to determine the values for those parts

                                2. use a linear voltage regulator, which basically takes some voltage and "burns" the extra voltage inside itself... it's a much simpler design, but as it turns excess voltage to heat, you need a heatsink and need to be aware it will be a bit hot.

                                ... you have 5 x 0.34 a fans ... if for example you adjust them to work at 8v, there's (12v-8v) x (5x0.34) = 6 watts of power dissipated into the heatsink as heat. This would heat up the heatsink to about 70c, probably... if you stick it to the side of the case, the case will radiate the heat better.

                                So you need:

                                LT1083 or LT1084 ... request samples if you want to do it cheap ...1083 does max 3A , 10084 does max 5A

                                2 x 10uF tantalum capacitors or one 10uF tantalum and one electrolytic that's at least 50uF

                                1 resistor and one potentiometer picked in such way that you can select voltages between low voltage and high voltage...
                                The regulator has about 1.1v drop inside itself, so you can only pick something between 3v and 11v, so :

                                Voutput = Vreference ( 1+ R2/R1) = 1.25 x (1 + R2/R1)

                                So if you pick R1 as 100 ohm, Voutput = 1.25 + 1.25 R2/ 100 ... :

                                for 3v output, that's : 3 = 1.25 + 1.25R2 / 100 = 140 ohm

                                for 11v output, that's : 11 = 1.25 + 1.25R2 / 100 = 780 ohm

                                So you can pick for R2 a 150ohm resistor + a 750 ohm potentiometer... this way when you have the potentiometer set at 0, you have 150 and 100 ohm, which is close to 3v

                                But you can go the other way around and select a 1k potentiometer from the start and determine R1 instead...

                                11 = 1.25 + 1.25 x 1000 / R1 => (11-1.25) x R1 = 1250 = > R1 = 1250/9.75 = 128 ohm, so pick a standard value close to this one.

                                Next step... you just take a breadboard or some pcb with lots of small holes and a heatsink and maybe a thermal pad (or that thermal paste you put on cpu heatsink) and solder the circuit like it's in the datasheet:



                                Page 15 actually shows you the circuit and they came to about the same values... 90.9 ohm and 1kohm potentiometer... they went with 90 ohm because they made it between 1.2v and 15v ... you only need about 3 to 11 as you only give 12v input, not more.

                                Comment


                                  #17
                                  Re: I need to make a fan controller.

                                  Here's my favourite: http://web.archive.org/web/200705182.../circuit3.html

                                  Originally posted by mariushm View Post
                                  The 3 pin headers tell you the fans change their speed by altering the voltage ... you have 2 wires for power and one to tell the computer the speed.
                                  So you can't use the PWM design with such fans.
                                  Yes you can. Full 0-100% PWM, real simple, works with any standard fan. Manual speed control and can handle big loads with a big MOSFET.



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                                    #18
                                    Re: I need to make a fan controller.

                                    Originally posted by mariushm View Post
                                    The 3 pin headers tell you the fans change their speed by altering the voltage ... you have 2 wires for power and one to tell the computer the speed.
                                    So you can't use the PWM design with such fans.
                                    You can use PWM to control the speed, but the tachometer signal won't work. I am using a 3-wire fan with my TC648-based fan controller. The motherboard in that computer doesn't have any fan connectors, so I wouldn't be able to measure the fan's speed anyway.

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                                      #19
                                      Re: I need to make a fan controller.

                                      Would be easier to run the fans off the 5v rail and set the 555 timer in "step up" configuration if you ask me. That should give you a 0% to let out the magic smoke control range
                                      Last edited by Evil Lurker; 02-04-2012, 05:46 PM.

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                                        #20
                                        Re: I need to make a fan controller.

                                        I tried to find the schematic for the fan controller I designed. Unfortunately I could not find it. I only have the board design. I have tested the design on a breadboard in the past and it worked brilliantly. However I would suggest you test out the circuit on a breadboard first.

                                        The part list is shown below. Keep in mind that I chose the components I did to minimise cost (around where I live). Some of them are incredibly over specified, however they are commonly available here for next to nothing. Getting a smaller or more appropriately sized component would have cost me a lot more. The best example of this is the Darlington transistor I chose. It is rated for up to 5A of power output. However a single fan only outputs 0.34A. Just a little overspeced. I am also assuming you want to control the speed of 5 fans with a single potentiometer.

                                        5x TIP120 - NPN Darlington Transistor
                                        5x 1kΩ resistors
                                        5x 1N5817 - Schottky Diode
                                        1x Potentiometer
                                        5x LED's
                                        5x 560Ω resistors

                                        The last two components are optional. They are simply indicator LED's (along with a current limiting resistor) so you can visually see which fan is being powered. You may need to adjust the resistor value for the LED to match the LED's which you are using.

                                        You may also wish to add a couple of capacitors to filter the voltage from the power supply a bit. I think this is optional as the power from the power supply should be pretty clean.

                                        With regards to a microcontroller. Since you are an amateur, I would highly recommend an Arduino microcontroller (or a clone). These are programmed with just a USB cable (they come with a bootloader preloaded on the microcontroller), no need for any special programmers or devices.

                                        Something like this is a good start:
                                        http://arduino.cc/en/Main/ArduinoBoardUno

                                        I think it would be pretty cool to design the circuit on an Arduino 'shield'. A shield is something like a daughter board which sits on top of the microcontroller. The daughter board connects all the pins from the controller to the daughter board and you can solder up a circuit in the middle and use those pins. You can solder up a circuit any way you wish, more complex designs will not fit on such a small shield, perhaps you can think about using stripboard (like my original idea) or create your own PCB.
                                        http://arduino.cc/en/Main/ArduinoProtoShield

                                        I have to create a schematic for you from scratch (I only have a stripboard design which is for a much more sophisticated fan controller than what you are after). The reason why I didn't post anything yet is because I am scared that when I draw up a circuit, I will have the diode or the LED polarity wrong which would cause the circuit to not function at all. I would like to test out the circuit again on a breadboard before I am comfortable releasing a schematic.

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