Stir Plate - Can't get the fan to move...at all

[hammacks]

Well Wifey is out of town this weekend so that means it's project time. I have this old PC I purchased for 30 bucks a while ago for I don't know what. I pulled the fan out and took the magnets out of the HD. I plan to start with a simple phone charger powered unit.

I have tried two chargers and neither have made the fan budge at all. This is without the magnets mounted. AFAIK, the fan worked fine in the computer. Any ideas?

FAN:12V DC Brushless
560mA (kinda high?)

LG Charger: 5V 1A

POS Charger: 4.5-9.5V (?) 800mA

 

[eriktlupus]

off hand i'd say not enough voltage. the computer fans are generally set to run on 12vdc or 120vac depending. i bought an old transformer from a surplus store for like 5$ or so, i did have to drop the push from it though,about 100ohms or so.

 

[hammacks]

Was I wrong in thinking that many people used CPU fans (all 12V right?) with around 5-6V?

*Off to check out stir plate threads again...

 

[HomebrewJeff]

Are you sure you have the wires hooked up correctly? That charger should be enough to at least get the fan to spin with no load. My stirplate uses:

Fan: 12v / 200ma / 110mm
Charger: 3.7v / 340ma

I've made as big as a 3 quart starter with it.

 

[hammacks]

tried polarity both ways...no go

I've now pulled out the PS fan and will give that a shot. It says 12V 250mA

 

[hammacks]

ok either the cpu fan is dead or the high amperage rating has something to do with it.

PS fan works. Now, until I get a stir bar in the mail, anyone rig one up themselves? and, Anyone use some oddly shaped stir "bars" and like them?

 

[eddiemeddiem]

Just to check... you tried swapping the polariy/leads of the power supply going to the fan, right? It's DC...

-Eddie

 

[BackBayBrewing]

I just built a stir plate today. I know you said that you tried the leads both ways, but I thought I would mention it again since I had this problem today. I just assumed when hooking them up that the black wire from the phone charger would be the ground like in the fan, but low and behold, the black was the hot and the green was the ground. As soon as I switched them... viola, the fan was off and running.

 

[BrewBeemer]

Well Wifey is out of town this weekend so that means it's project time. I have this old PC I purchased for 30 bucks a while ago for I don't know what. I pulled the fan out and took the magnets out of the HD. I plan to start with a simple phone charger powered unit.

I have tried two chargers and neither have made the fan budge at all. This is without the magnets mounted. AFAIK, the fan worked fine in the computer. Any ideas?

FAN:12V DC Brushless
560mA (kinda high?)

LG Charger: 5V 1A

POS Charger: 4.5-9.5V (?) 800mA

At 560 mA pushed by 12 volts that would make a rather strong fan, I would keep it and and use it.
I have a collection of Sun Micro Systems 720 mA 12 volt fan motors 120 mm diameter. Those 200 mA or less energy saving fans are gutless low torque wonders. Your on the right track. I use 1,500 mA 12 volt power cubes. I will order a LM317 1.5 amp voltage regulator kit and solder it together, add a Radio Shack plastic project box with a few parts and a cord then ready to assemble. I'm thinking of a 1/4" plexi mounted ring to center the flask centered over the magnet and the fans center, no shifting around looking for the center of the magnets alignment just install the flask and forget. This for one of my yeast stir fan projects. Screw those lower voltage power suppplies as well those low mA fans, better to have the extra voltage and cut it back than have a under powered stir plate. leave the watt counters to the worlds "Green People" I want to brew without problems. JMO's no flaming replies from the save the world greenies.

 

[Catt22]

Every once in a while, I like to toss in this pic of my DIY stirplate if for no other reason than to show that there is another way to do it.

This is a 110 V AC muffin fan w/rare earth magnets & using a light dimmer for speed control:

That's a 2 liter flask fully filled and a 2 inch stir bar. Been using it without problems for about four years now and have built several more for friends.

 

[BrewBeemer]

catt22; and like a dummy I had a box full of 120 mm 120 volt fan motors like 37 of them from a garage sale for $10. They were around the house for 2 years, the wife got mad at my collecting crap (they get that way) so I donated them to the high schools electric shop instructor for student projects. I felt better as I went thru the same class many moon ago.

And yes if one has a 120 volt fan motor just add the cost of a dimmer and your done like catt22's stir project. A PITA if a radio is used near the dimmer as it puts out a lot of RRF noise.
Someone stated a 80mm fan, this I find rather small as well those lower mA 12volt 120 mm fans, this will also lower your low speed where you need it rpm's torque. Better to get a 120 mm fan with a 500 mA plus motor. Like I posted above the six 720 mA fans saved from a tower power supply has plenty of torque that's within 90% of Claudius B's 24 volt 400 mA stir plate, he has great results without any problems with his unit.
I recall most small pots are only rated up to 3 watts, I smoked one on a 720mA fan that would run without a magnet load at 640 mA up to 690 mA under a magnets load with a thick starter. Locked rotor would hit 900 mA and the fans thermo set dropping out. I have a 20 and 40 ohm 10 watt resistor for speed control for now until I order a LM317 voltage regulator for zero to full speed control, better than the two speed I have for now. This a $9.95 regulator with all the parts plus a PC board, you assemble and solder. It comes with a few parts plus a large star-burst aluminum heat sink plus 1.5 amp output. There are lower output units of 500mA as well 3.3 / 5 volt adjustable and fixed voltage at $4.95 with adjustable voltage parts kits for $6.95 to $7.95. This will not break the bank plus allows you a running sir plate, money well spent for the price vs fighting a project that has failed. Replace the trimmer pot with a regular pot mounted on the project box with a switch and LED power on light your good to go. To run the fan directly off a pot I have let the soke out as well had 5 watt hollow wire wound resistors that ran rather hot, solid square 5 watt that would melt plastic, not my idea of speed reducing. Spend many hundreds to thousands of dollars on a hobby they go cheap with failed results is flat not thinking straight how I see it.
Since I already have these 12 volt motors a adjustable power supply will complete this project otherwise I would go the 120 volt dimmer direction if I had a 120 volt fan. The flask base flatter the better as well the magnets set almost touching the inside of the box with the flask centered over the fan will solve a lot of magnet throwing problems. Are you sure you hooked the motor up correctly as reverse polarity they play dead, swap leads they run plus you may have a temp sensor on that fan, do not hook power to those leads. Done ranting on this stir plate project, it's too nice to be indoors today.

 

[hammacks]

Just to check... you tried swapping the polariy/leads of the power supply going to the fan, right? It's DC...

-Eddie

Not sure if you guys caught it but I did get the PS fan to work. I think I was underpowering the CPU fan (which I will hang onto)

 

[woollybugger2]

CAT22

my cooling fan has trouble running with a magnet on it, i've got a nice motor out of a copier, actually about 5 or 6 and have be trying to figure out how to mount them. You photos have inspired me

 

[Catt22]

Woolly,

check your message box

 

[Hang Glider]

Wooly, same thing at first - HD magnets are so strong, they were influencing the motor itself. Found a bit of plastic to raise the magnet off the motor somewhat, world of difference.

Hopefully your switch to copier motor will work for you, but the cooling fan is still an option...

 

[johnnyc]

ok either the cpu fan is dead or the high amperage rating has something to do with it.

PS fan works. Now, until I get a stir bar in the mail, anyone rig one up themselves? and, Anyone use some oddly shaped stir "bars" and like them?

I just built my first stirplate and ordered a 1 1/2" "starburst" stirbar. Seems to work great but I had to make sure the neck of my container I was making my starter in had a wide enough neck. I ended up having to use a stainless steel pitcher from the kitchen b/c I don't have a flask and my 1 gallon apple juice jugs have a curved bottom that the stirbar wouldn't center on.

 

[hammacks]

I just built my first stirplate and ordered a 1 1/2" "starburst" stirbar. Seems to work great but I had to make sure the neck of my container I was making my starter in had a wide enough neck. I ended up having to use a stainless steel pitcher from the kitchen b/c I don't have a flask and my 1 gallon apple juice jugs have a curved bottom that the stirbar wouldn't center on.

How large is the pitcher? I'm hoping to be able to go up to a a gallon for high gravity brews.

 

[hammacks]

OK while waiting for a stirbar I've been trying to add speed control using a 25ohm rheostat. Here's what's going on:

5V 1A Cell phone charger
12V 250mA Fan
in serial with a on/off switch, LED, and 25ohm pot.

Without the pot, everything worked fine, but was fast. With the pot the fan never moves, and the light is off. Any help?

EDIT: It was actually a bad wire. I fixed that but then still couldn't get the fan to go. Once I bypassed the LED, everything worked great. I guess I'm getting to much of a voltage drop across my LED so I'll just leave it bypassed for now.

 

[johnnyc]

OK while waiting for a stirbar I've been trying to add speed control using a 25ohm rheostat. Here's what's going on:

5V 1A Cell phone charger
12V 250mA Fan
in serial with a on/off switch, LED, and 25ohm pot.

Without the pot, everything worked fine, but was fast. With the pot the fan never moves, and the light is off. Any help?

EDIT: It was actually a bad wire. I fixed that but then still couldn't get the fan to go. Once I bypassed the LED, everything worked great. I guess I'm getting to much of a voltage drop across my LED so I'll just leave it bypassed for now.

I'm using a 5V charger w/ a 12V fan following the DIY stirplate instructions. One thing I had to do was put a significant spacer between the fan and the HD magnet. The magnet seems to significantly affect the fan motor. My spacer is almost an inch thick and I really needed that much separation to make sure it wasn't putting a strain on the motor. My rheostat doesn't get the fan turning until halfway around the dial but the stirbar gets thrown by 3/4 around anyway so that seems to be plenty. I would look into spacing it out further. Just my .02.