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charlie93
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| Motor speed control using pot |
 Posted: Wed Dec 23, 2009 12:13 am |
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hye all,
I would like to use pc fan (the one inside pc) in my experiment (just a small hobby lol).
My question is can I use a pot to control the motor speed?
The fan use pwm right? So that means the pot is used to modify pwm signal, is it possible? I would like to use 16f84 pic.
How can I do this? Anyone can give advice or helpful link? |
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bungee-
Joined: 27 Jun 2007
Posts: 206
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| Posted: Wed Dec 23, 2009 12:59 am |
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Use PIC with PWM module. Old 16F84 is not a good choice here. I did similar project with small 12F683  |
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charlie93
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| Posted: Wed Dec 23, 2009 10:08 am |
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can i see it?
the layout or circuitry |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Dec 23, 2009 1:27 pm |
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On a PIC that has a hardware PWM module, this test program shows
how to set the pwm duty cycle with a trimpot:
http://www.ccsinfo.com/forum/viewtopic.php?t=40007&start=1
If you used PWM to run a motor, a larger duty cycle would give a
faster motor speed. A smaller duty cycle would give a slower speed. |
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bungee-
Joined: 27 Jun 2007
Posts: 206
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| Posted: Wed Dec 23, 2009 3:47 pm |
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| charlie93 wrote: | can i see it?
the layout or circuitry |
This is working prototype version. KLIK here |
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mkuang
Joined: 14 Dec 2007
Posts: 257
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| Posted: Wed Dec 23, 2009 3:51 pm |
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| bungee- wrote: | | charlie93 wrote: | can i see it?
the layout or circuitry |
This is working prototype version. KLIK here |
What does C2 do? Some kind of snubber? |
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bungee-
Joined: 27 Jun 2007
Posts: 206
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| Posted: Wed Dec 23, 2009 4:27 pm |
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Yes a snubber, C2 removes the noise and at low speeds motor is running smoother. C2 is ~1uF or so. If you put in larger C2, than the upper duty rates "disappear".
On the schematic values are not correct. BAS15 is not the correct type - it was put there because of the size of real element. It should be fast shotky diode with enough voltage/current ratings for the motor type.
Schematic provided is for "educational" purposes |
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mkuang
Joined: 14 Dec 2007
Posts: 257
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| Posted: Wed Dec 23, 2009 4:29 pm |
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| bungee- wrote: | C2 is ~1uF or so. If you put in larger C2, than the upper duty rates "disappear".
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Yeah, that's why I was wondering why there is a cap there... |
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