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-   -   DIY Stirplate help (http://www.homebrewtalk.com/f51/diy-stirplate-help-123063/)

chode720 06-09-2009 02:28 AM

DIY Stirplate help
 
So I am trying to make my own stirplate and have run into a bit of a problem (well a big problem)

I followed the instruction from Anthony Lopez www.homebrewtalk.com/f51/my-stirplate-cheap-easy-build-86252/ however, when I turn on my stirplate, the fan just rocks back and forth for about a half second and then doesnt spin. The LED light on the rocker switch comes on so I am assuming that it means the circuit is good. I checked all of my connections and all them are on snug and all the wires are crimped in the connectors well.

I cant figure out why the fan won't spin. I have adjusted the knob on the rheostat and there are no changes at all. The only thing I can think of is the voltage on my power supply is too high. After figuring out it wasnt working, I checked the old cell phone charger i am using for a power supply and its printed, 30V, on the cable. Could there be an issue if the voltage is too high? I dont have much knowledge on electrical, but did notice that Anthony says to use a charger betweeen 5-12V

Thanks for any help

PintOfBitter 06-09-2009 02:35 AM

30v is your problem. the fan is rated at 12, but will spin too quickly at that voltage. Mine, for instance needs about 4v to get a proper speed.

You may have damaged the circuitry that drives the brushless motor, but it may be fine and just acting wonky due to the excessive voltage.

Find a lower voltage power supply and hopefully you'll be in business.

EDIT: Just reread your post. the printing on the cable is just the rated voltage of the actual wire and insulation. the voltage of the adapter is printed or embossed on the wall wart.

Thirsty_Monk 06-09-2009 03:54 AM

Not all computer fans are created equal. Do you have another fan to try?
I had better luck with smaller (size) fans and with 9v power supply (12V would be the best in my case).

Do you have your fan wired correctly? Computer fans does not like reverse polarity. Try switching your wires.

chode720 06-09-2009 10:32 AM

I checked the charger and the output is only 5V.


The fan is wired with the black wire to the earth side of rocket swith and the red wire is to the supply side. There is a white wire on the fan that isn't being used

TommyBoy 06-09-2009 11:48 AM

Mine did the same thing and when I took the fan out I noticed that the retaining ring for the fan had come off and the magnetic attraction had pulled the fan blade up and out of the rest of the fan assembly once I but the flask and stir bar on top. Check and see if your fan is still secured inside it's housing.

chode720 06-09-2009 11:52 AM

Quote:

Originally Posted by TommyBoy (Post 1371131)
Mine did the same thing and when I took the fan out I noticed that the retaining ring for the fan had come off and the magnetic attraction had pulled the fan blade up and out of the rest of the fan assembly once I but the flask and stir bar on top. Check and see if your fan is still secured inside it's housing.

Okay I will check that later when I get home. I did try spinning the fan by hand and it semmed to be okay

PintOfBitter 06-09-2009 02:15 PM

I had problems with the magnetic attraction to the stirbar levitating the fan body also. It's not easy to fix, and ends up being a balancing act to get the right distance to the stirbar so that it won't get thrown but won't pull up your fan body.

chode720 06-09-2009 02:22 PM

I dont have any of the magnets or stir bar with the system yet. I was just trying to test the wiring and the fan before I glued the washer down and attached the magnets.

There was a red, black, and white wire on the fan. Do I need to do anything with that white wire?

EDIT: I did a little research and found that the Dell CPU fans have a 3rd white wire that is the speed control wire. I would venture a guess that without the speed control wire hooked up the fan wont spin?

chode720 06-09-2009 06:20 PM

/bump

Any other ideas?

PintOfBitter 06-09-2009 07:15 PM

the speed control wire is purely a tach pickup feedback to the motherboard. I really don't think it needs to be hooked up.

Remove the magnet from the fan and see if it spins. I had to put the magnet on standoffs so that it didn't interfere with the motor.

You're using a case fan, not a CPU fan, right? I don't know if a dinky little CPU fan will do the job.


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