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DYI fan controller - Page 4

post #31 of 40
5/17/12 at 12:46am
Quote:
Originally Posted by just_nuke_em View Post

I gave PWM a shot and had trouble with it dumping transients on the 12V rail due to the kickback from the fans being pulsed (think what happens when you suddenly cut current to an inductor). A buck converter is the best one imho, or even buck-boost if you want over volt your fans a bit. I got a relatively simple design I've been thinking of implementing just for proof of concept.

In my design I managed to reduce these transients by using a Schottky diode (specifically an SBR) in flyback configuration across the motor and a large capacitor across the 12V rail (1000+ microFarad). My design consisted of only these two components along with a MOSFET and it's corresponding series and pull-down resistors for the gate. The MOSFET was driven from an IO pin on a PIC microcontroller.

Unfortunately I can't find the schematic and I don't have time to redraw it but I'm you sure you get the idea.
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post #32 of 40
5/17/12 at 12:54am
Quote:
Originally Posted by mr one View Post

yeah, here is all that you gonna need smile.gif Note, and a big one: You gonna need to really keep cool thoose transistors because if they get hot then just shuts off smile.gif i am thinking about one idea, to double this one schematic and make 16 fans controller, but something like smaller version of this one, something like 8 channels that can hold 4 fans on each, and try to find some maybe other transistor to use, and btw if you wanna make a pvm controller you can use 555chip smile.gif
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Just something I noticed - shouldn't the transistor output be going to the MIDDLE pin of the fan? It looks like the diagram shows it going to the PWM_OUT signal, which means the fans wouldn't run?

smile.gif
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post #33 of 40
5/17/12 at 3:23am
Thread Starter 
Quote:
Originally Posted by latelesley View Post

Just something I noticed - shouldn't the transistor output be going to the MIDDLE pin of the fan? It looks like the diagram shows it going to the PWM_OUT signal, which means the fans wouldn't run?
smile.gif

and its going in to middle of fan pin smile.gif And its not a pwm controller, it controlls just a voltage of fans smile.gif
Edited by mr one - 5/17/12 at 6:13am
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post #34 of 40
5/25/12 at 9:09am
sorry, its just that the circuit traces looked like they were going to the outside pins of the fan connectors. smile.gif Still, its a brill project. I'd like to do one where it read the pwn_out signal, and could show the fan rpm on a display. smile.gif
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post #35 of 40
5/25/12 at 2:50pm
Thread Starter 
Quote:
Originally Posted by latelesley View Post

sorry, its just that the circuit traces looked like they were going to the outside pins of the fan connectors. smile.gif Still, its a brill project. I'd like to do one where it read the pwn_out signal, and could show the fan rpm on a display. smile.gif

PWM controllers basic you can do is with 555 chip, i can find scheme if you wanna try smile.gif
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post #36 of 40
5/26/12 at 1:28am
I'm familiar with using a 555 in PWM mode - and TBH it wouldn't be my chip of choice to do a PWM controller for 4 pin fans. What I meant with the PWM_OUT, - you know I just realised i'm calling it wrong, its the tach_out, isn't it? I meant a controller that could read and display fan speed. It may be a next year project for me, as more important just now is to get the parts to water cool my PC. It just runs too hot, and I think I need water to tame the temps. :-)

Thank you for the offer though! smile.gif

Lesley x
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post #37 of 40
5/26/12 at 1:36am
Thread Starter 
Quote:
Originally Posted by latelesley View Post

I'm familiar with using a 555 in PWM mode - and TBH it wouldn't be my chip of choice to do a PWM controller for 4 pin fans. What I meant with the PWM_OUT, - you know I just realised i'm calling it wrong, its the tach_out, isn't it? I meant a controller that could read and display fan speed. It may be a next year project for me, as more important just now is to get the parts to water cool my PC. It just runs too hot, and I think I need water to tame the temps. :-)
Thank you for the offer though! smile.gif
Lesley x

oh now i understand biggrin.gif
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post #38 of 40
6/18/12 at 10:19am
Thread Starter 
soon gonna be updte time, made some traces by hand and whats left is to put it in acid
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post #39 of 40
8/4/12 at 10:29am
nice work smile.gif

I recently build my own controller,
a dual channel with very similar design with yours as well smile.gif

7649454154_215a84d09d_c.jpg

should be enough to drive 4 fans inside my case wink.gif
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post #40 of 40
8/4/12 at 10:35am
Thread Starter 
Quote:
Originally Posted by inVain View Post

nice work smile.gif
I recently build my own controller,
a dual channel with very similar design with yours as well smile.gif
7649454154_215a84d09d_c.jpg
should be enough to drive 4 fans inside my case wink.gif

Your version really looks good, effing good smile.gifthumb.gif
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