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 Hyphilion
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 Comp fan stir plate - I have Red, Black & Yellow wires. How do I use Yellow to adjust speed? 
#12552063 - 05/12/10 08:40 PM (2 years, 15 days ago) |
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Hello,
I am using a a DC12V 0.27A computer fan with R, B & Y wires, and a 100-240V/AC 50-60Hz 0.2A LG ac adapter (cell phone charger) with an output of 5V.
Anyways,
The fan has R B and Y wires, how do I use the ground (yellow) wire to adjust the speed of the fan?
Thanks. Also, does the above set up sound perfectly safe? THx 
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Bojangles
( . Y . )
Registered: 04/29/10
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 Re: Comp fan stir plate - I have Red, Black & Yellow wires. How do I use Yellow to adjust speed? [Re: Hyphilion]
#12552098 - 05/12/10 08:44 PM (2 years, 15 days ago) |
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with a potentiometer got to radio shack. its got a little nob u turn to increase or lower the resistance
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  everything i say is bullshit... 
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 fastfred
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Registered: 05/17/04
Posts: 6,242
Loc: Dark side of the moon
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Re: Comp fan stir plate - I have Red, Black & Yellow wires. How do I use Yellow to adjust speed? [Re: Bojangles]
#12552184 - 05/12/10 08:57 PM (2 years, 15 days ago) |
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The third wire is a rotation sensor. It has nothing to do with adjusting speed.
You can vary the speed a bit with voltage, but you need a PWM controller to do it right.
-FF
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Hyphilion
Occultist Ecologist
Registered: 07/27/09
Posts: 69
Loc: Nexus of Texas
Last seen: 7 months, 20 days
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Re: Comp fan stir plate - I have Red, Black & Yellow wires. How do I use Yellow to adjust speed? [Re: fastfred]
#12552289 - 05/12/10 09:16 PM (2 years, 15 days ago) |
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Thanks Fastfred,
can you elaborate on a PWM controller, how to install one into this setup, and where to buy one?
Thx
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fastfred
Old Hand
Registered: 05/17/04
Posts: 6,242
Loc: Dark side of the moon
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Re: Comp fan stir plate - I have Red, Black & Yellow wires. How do I use Yellow to adjust speed? [Re: Hyphilion]
#12552399 - 05/12/10 09:37 PM (2 years, 15 days ago) |
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You can get any of the PWM computer fan speed controllers on ebay. They don't cost all that much, but they're more than a pot by a fair bit.
PWM stands for pulse width modulation. Basically instead of varying the voltage, which can result in stalling, it pulses the same voltage at varying pulse widths. e.g. 90%, 30%, etc.. This varies the speed of the fan without letting it stall at slower speeds, which is probably what you're looking for.
It's kind of like gunning the engine repeatedly instead of trying to run it at idle speed.
-FF
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Hyphilion
Occultist Ecologist
Registered: 07/27/09
Posts: 69
Loc: Nexus of Texas
Last seen: 7 months, 20 days
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Re: Comp fan stir plate - I have Red, Black & Yellow wires. How do I use Yellow to adjust speed? [Re: Hyphilion]
#12552498 - 05/12/10 09:55 PM (2 years, 15 days ago) |
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FF,
Would you suggest something like this?
http://www.hobbytron.com/vk8004.html ; because $20 seems like a lot to pay for something that I was hoping would be DIY.
Any suggestions of particular/cheap PWMs to buy? How much would a decent but cheap one cost? Thx again amigo
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fastfred
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Registered: 05/17/04
Posts: 6,242
Loc: Dark side of the moon
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Re: Comp fan stir plate - I have Red, Black & Yellow wires. How do I use Yellow to adjust speed? [Re: Hyphilion]
#12554982 - 05/13/10 11:00 AM (2 years, 14 days ago) |
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If you want to DIY you can get a PWM controller chip and build your own.
I don't really have any experience in this area. But drag from the stirbar is going to put a variable load on your fan. So I think simple voltage control won't work that well, especially since for a stir setup you're wanting to run the fan way below it's rated RPMs.
-FF
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PrimalSoup
stronger than dirt
Registered: 11/17/09
Posts: 3,130
Loc: PNW
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Re: Comp fan stir plate - I have Red, Black & Yellow wires. How do I use Yellow to adjust speed? [Re: Hyphilion]
#12555350 - 05/13/10 12:11 PM (2 years, 14 days ago) |
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Already at 5V supply for a 12V fan you'll be in stall mode with any significant load. Do it with PWM from a 12V supply and it should work fine.
Peace
-PS
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Hyphilion
Occultist Ecologist
Registered: 07/27/09
Posts: 69
Loc: Nexus of Texas
Last seen: 7 months, 20 days
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Re: Comp fan stir plate - I have Red, Black & Yellow wires. How do I use Yellow to adjust speed? [Re: PrimalSoup]
#12563550 - 05/14/10 05:10 PM (2 years, 13 days ago) |
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Thanks for the pointers.
I just taped on my small neody-something magnets i ordered online onto the fan.
It runs fine with the wires connected, so I am not sure what you mean by stall.
I was just playing with it, and I think if i just pulse it a few times a day, an LC would be just fine, right?
The pulse width modulator, I assume, is something one would find on a lab-grade stir plate?
Thx
Edited by Hyphilion (05/14/10 05:23 PM)
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Hyphilion
Occultist Ecologist
Registered: 07/27/09
Posts: 69
Loc: Nexus of Texas
Last seen: 7 months, 20 days
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Re: Comp fan stir plate - I have Red, Black & Yellow wires. How do I use Yellow to adjust speed? [Re: Hyphilion]
#12613659 - 05/23/10 09:54 AM (2 years, 4 days ago) |
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Ok,
I did some research. Circuits are fascinating.
I found some tutorial-ish stuff on PWMs.
For example--
-A schematic on how to build a PWM (the index of this site includes schematics on how to build all kinds of basic electronics. very interesting):
http://www.aaroncake.net/circuits/motorcon.asp
-A link on how to read circuit schematics:
http://www.buildinggadgets.com/index_key.htm
-Sweet, just what we are looking for: a PWM controlling the speed of a computer fan
the most helpful thing i have found on building a PWM.
-A PWM tutorial video:
another PWM tutorial video, but this one is long (5 parts) and totally step by step:
These videos have answered all of my questions regarding Pulse width modulation in controlling the speed of a computer fan. Especially the last two videos.
Please feel free to contribute any electronic/circuitry knowhow to this threat, or links to websites on relevant tutorials, index of schematic symbols, etc.
Edited by Hyphilion (05/23/10 10:11 AM)
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