My homebrew stirplate

[Homercidal]

The last stirplate I made used Wonderflonium Magnets coupled to an Inverse Reactive Intensifier. My idea was to control vortex creation with a reactive feedback circuit sensing motion/flow. Unfortunately the Scotch Tape I had used to hold the feedback circuit onto the flask gave way and the IRI ran loose. Before I could unplug it, it had created an antimatter field proportional to the mass of the Wonderflonium, squared.

I'm grateful that nobody was hurt, but that was the last of my Wonderflonium, and now I can't build that Freeze Ray I had my heart set on!

 

[PintOfBitter]

I'd offer to share some of my wonderflonium, but I used the last module in my .

 

[DonLiguori]

Okay, so I know this thread has been killed and resurrected several times, so I'm sorry. But I can't shake the feeling that I've just scrapped a perfectly good 1 Gig HDD from my first computer and am not using it to it's full potential.

I have in my hands a 12v brushless motor and perfectly smooth palette to place the magnets on that would seem to be perfect for the plate... but does anyone know how to wire a system that could use a potentiometer on a HDD spindle drive? I have no idea when it comes to electronics, but would love to see this thing back in motion.

From Wolfenstein 3D to a perfect yeast pitch!

 

[jim_reaper1066]

Just ripped a 12V DC fan out of an old computer, and wired it up to a 12V speaker wall jack. When I set a rare earth magnet from a HD on the back it holds itself on. When I turn the fan upside down the speed decreases quite a bit, is this normal for computer fans?

 

[hexmonkey]

but does anyone know how to wire a system that could use a potentiometer on a HDD spindle drive? I have no idea when it comes to electronics, but would love to see this thing back in motion.

I believe a spindle drive from a hard drive is what's known as a "stepper" motor. Those are made for precision movements (even if that movement is spinning fast -> spinning faster), and so require an actual controller giving signals to it. Way more electronically complex than a 10k pot, and therefore probably not worth the trouble.

Just ripped a 12V DC fan out of an old computer, and wired it up to a 12V speaker wall jack. When I set a rare earth magnet from a HD on the back it holds itself on. When I turn the fan upside down the speed decreases quite a bit, is this normal for computer fans?

I've never seen that happen but it might be the way the blades are connected to the motor. The weight of the magnet may be pulling the spindle out of alignment and causing friction.

 

[ekjohns]

i bought all the parts to make this stir plate. My concern is i got a 3mm blue LED with a voltage rating of 3.5-4V. What would be the best way to hook this up without burning it out?

 

[boogyman]

i bought all the parts to make this stir plate. My concern is i got a 3mm blue LED with a voltage rating of 3.5-4V. What would be the best way to hook this up without burning it out?

Depending on your power supply, just add a resistor inline with the led to drop the voltage to your 3.5-4V.

 

[BrewBeemer]

Depending on your power supply, just add a resistor inline with the led to drop the voltage to your 3.5-4V.

Make sure the resistor wattage matches the wattage of the motor to handle the heat created by the voltage it's holding back so it doesn't burn up. A wire wound hollow center tap resistor with slider, Ohmite a brand name example will work great plus adjustable resistance. larger wattage than the motor load will not hurt.

 

[Scimmia]

Make sure the resistor wattage matches the wattage of the motor to handle the heat created by the voltage it's holding back so it doesn't burn up. A wire wound hollow center tap resistor with slider, Ohmite a brand name example will work great plus adjustable resistance. larger wattage than the motor load will not hurt.

I certainly wouldn't run the fan/motor off the same resistor as the LED.

ekjohns, you need to calculate what resistance you need by knowing the current (mA), the forward voltage (vf) of the LED, and the voltage of your power supply. You would hook all of that up in parallel to your fan controller.

http://www.quickar.com/noqbestledcalc.htm

 

[ekjohns]

It will be either a 12VDC 500mA or 12VDC 1A power supply. I can get either for the same price. So would a 470 ohm 1/2W resistor work hooked straight from the power supply? Do you recommend one power supply over the other?

Scrimmia - thanks that is exactly what i needed, any thoughts on the Amp raiting of the power supply?

 

[ekjohns]

For knowledge sake what is the raw equation to calculate the resistance needed. Just want to prove to myself i can do the actual math i use to do in high school

 

[Scimmia]

Assuming the LED is wanting 20 ma (typical max), yeah, the 470 1/2W should work fine. Really, a 1/4W should do the trick.

The power draw of the LED/resistor combo is going to be virtually negligible in this case, so size the power supply based on the fan, figuring in some overhead for the control circuit.

Edit: the calculation is just Ohm's law. V=IR. We need the resistance, so R= V/I. The LED is going to drop 4 volts, so the resistor needs to drop 8. R=8/.020=400 ohm.

 

[BrewBeemer]

As stated above "go larger for control current demands", by this I would use the larger power supply should you add other future loads your golden.

 

[ekjohns]

I have a 9v power supply that i would like to use. This would be with the LM317T controller and a 80mm 12V fan. many people talk about the stir plate throwing bars at top speeds. Would a 9V power supply still give me a wicked vortex or is a 12V necessary?

 

[camiller]

I have a 9v power supply that i would like to use. This would be with the LM317T controller and a 80mm 12V fan. many people talk about the stir plate throwing bars at top speeds. Would a 9V power supply still give me a wicked vortex or is a 12V necessary?

The answer to that question (as most things in life) is -- it depends.

Not all 80mm 12V fans have the same top RPM, some are slower at full speed than others.

for example this fan has a speed of 2500 RPM while this one tops out at 1700 RPM. Both are 12v 80mm computer case fans.

Mine will pull a vortex to the bottom of a 1L flask at 9v, but I generally run at 4.5v because you don't need to pull a "wicked vortex" all you really need is to keep the starter moving.

 

[ekjohns]

Yeah that was my thought that most fans to get a nice vortex will only be running at 9V max so the extra 3 volts is just a bonus. it would be cool to find a 11V power supply so i could say "but this goes to 11"

 

[camiller]

Yeah that was my thought that most fans to get a nice vortex will only be running at 9V max so the extra 3 volts is just a bonus. it would be cool to find a 11V power supply so i could say "but this goes to 11"

oblig: http://xkcd.com/670/

 

[jtkratzer]

Just ordered the following from Jameco:
Part # Description
15270 @ CAP,CERM,DISC,.1uF,50V,20%
23579 IC,LM317T,TO-220,
29082 POT,LINEAR TAPER,1/2W,10K OHM
162481 KNOB,1/4"SHAFT,METAL,RND,SLVR,
330772 @ CAP,RADIAL,1uF,50V,
577221 SWITCH,ROCKER,RRA22H3BBBNN,
609545 @CAP,RADIAL,0.1uF,50V,
637183 LED,PANEL MOUNT,GREEN,T13/4,
690865 @ RES,CF,1K OHM,1/4 WATT,5%,
696722 HEAT SINK,TO-220,1 HOLE,2 PINS

Going to Radio Shack for the enclosure, the power supply jack, and board.

 

[jtkratzer]

I just harvested 6 magnets from some hard drives on the way to be destroyed at work and it got me thinking when I was stripping these down to the bare chassis - is anyone using the motor from the drive that spins the platter?

 

[jtkratzer]

Finished everything but a bit of glue and positioning the magnets tonight. I'm hoping to be finished tomorrow. I wired the LED to the board and jumped to the leads to the fan so I'll know if the circuit is intact rather than just knowing if I'm getting power. I have a 12V and 9.4V power source thar both have M-sized jacks.

I used a set of instructions online for the circuit, but rather than just pile up the solder when putting the wire leads in, I ran them through the board and jumped with solder rather than wiring the underside of the board.

 

[oregonparamedic]

Just finished up mine. I don't have a stirbar yet but a bent paperclip pulled down a small whirlpool for the test!

 

[nduetime]

A couple of questions...

Would it be better to get a fan with higher RPM's? I understand the lm317 and potentiometer will adjust the speed but I'm thinking of worst case senario here.

Also, does the size of the stir bar depend on all the other factors (placement of fan from flask, magnet quantity and quality, etc.?) I'd prefer not to have to make additional web purchases, paying more for shipping, if at all possible. If there's no way really to predict which bar will be needed for my setup, what are the 2-3 sizes I should get (1", 1.5", 2", etc.?)

Thanks.

 

[CrazedArmadillo]

If there's no way really to predict which bar will be needed for my setup, what are the 2-3 sizes I should get (1", 1.5", 2", etc.?)

stir bar size mostly depends on the spacing between the magnets. If your magnets are 1" apart, then a 3" stir bar won't work too well. When I put my stir plate together, I bought the stir bar and some rare earth magnets. Then I stuck a magnet on each end of the stir bar. The magnets will naturally come to rest at the proper spacing. I then glued the magnets in place at this spacing, then stacked an additional magnet on each side for added strength. Works like a champ...never once thrown the bar.

 

[nduetime]

stir bar size mostly depends on the spacing between the magnets...

Thanks for the reply. Do you have a suggestion on what two size stir bars would be a safe bet?

 

[CrazedArmadillo]

I used a 1.5" bar for my stir plate, and it works great in a 2 Liter flask. The trick to using a larger stir bar is that you can't mount the magnets directly on the fan...they would be too close together. Plus, I'm not a fan of mounting magnets directly on a fan anyway, because they interfere with the magnetic field needed to run the motor.

This is what I did:

I bought these magnets http://www.truevalue.com/product/6-Piece-Neodymium-Super-Magnets/13923.uts at a True Value hardware store. They are very strong, and work a lot better than hard drive magnets.

Then I bought a 3/4" PVC pipe coupling
http://www.homedepot.com/h_d1/N-5yc1v/R-202303522/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

and bought some 1/2" tube straps
http://www.homedepot.com/Plumbing/h_d1/N-5yc1vZbqew/R-100201267/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

The PVC coupling was the same diameter as the center hub on my 80mm fan. I glued it in place, making sure it was balanced. One of the 1/2" straps then fits into the 3/4" coupling, leaving me two perfectly spaced mounting locations for my magnets. I then glued a magnet to each pad, making sure opposite poles are up (and using the stir bar to properly space them). Finally, I stuck an additional magnet on each side for added strength.

The PVC coupling works really well in this application, because it adds space between the fan motor and your magnets....hence, less interference.

In addition, you could assemble multiple 1/2" straps with magnets at different spacing for different sized stir bars....or instead of adhering magnets directly to the straps, place your magnets on a thin, lightweight strip of something that screws on to the bracket. Then, if you need to use a bigger stir bar, you could just swap out the bracket or strip.

EDIT: sorry about the blurry pictures...phone was acting up that day. I also failed to take a picture with the magnets in place...

 

[nduetime]

I used a 1.5" bar for my stir plate, and it works great in a 2 Liter flask. ...

Thank you for the advise. I'll look at that size when I order.

 

[theveganbrewer]

In case anyone is unfortunate enough not to have a 12, a 9, or even a 6v power adapter in the house, usefulgadget, on ebay is selling the ones needed for this build for 3.89 with free UPS shipping.

 

[nduetime]

Can someone help me out? I'm trying to figure this out but am getting no where. It's my first attempt at soldering and while the information in this post as well as this site are good, my frustration is starting to set in. I'm just looking for help through this.

Here is a quick drawing I did which represents what I have soldered right now.

Does this look right? Also, where does the on/off switch get wired in at?

If anyone is kind enough to help, I would greatly appreciate it.

Thank you, in advance.

 

[nduetime]

ok....so I now have the fan running. I have two problems.

The first is it doesn't seem to have any adjustment in the fan/POT. It's only a 500 RPM fan (super quiet) so I'm not sure if that really has anything to do with it.

Second, I don't have the on/off switch wired in because I'm a little confused how to do so. Can anyone post a picture of where it is in line with the other devices? I just need a photo to reference.

 

[cdwiggi]

Hello all,

I built my stir plate out of magnets from Home Depot and have a 12v 2 amp DC computer fan turning it. The problem is though every time I place the stir bar or anything mettle on it is throws it off? The stir bar is a square type like these. What I was wondering is why does it seem to be doing this?

Thanks
cd