Stir plate computer fan died

Well the subject line says it - the computer fan I used for my cobbled up stir plate died on me. If I whack it it hums and tries to spin but it won't go on it's own. I've only used it maybe 6 or 8 times for a couple of days each.

I glued two sets of HD magnets to the hub and I ran it off of a LM317 voltage regulator circuit like this https://www.homebrewtalk.com/f11/my-homebrew-stirplate-8850/

Has anyone else had a problem with poor fan life? This was a brand new 120mm from Best Buy.

I had a similar problem with my DIY stirplate. It turned out that the power supply that I was using went bad. Check the voltage out of your power supply. The fan might be okay.

Cheap CHINA crap victim???

I have had my fan stop the last time I used it. it started back up after taking the flask off the stirplate. I think the magnets are interfereing with the magnets in the fan motor. i am going to put another insulating washer between the drive magnets and the motor for more insulation.

67coupe390 said:

Cheap CHINA crap victim???

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Frankly, this was my first guess.

Joshua618 said:

I had a similar problem with my DIY stirplate. It turned out that the power supply that I was using went bad. Check the voltage out of your power supply. The fan might be okay.

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I have a 12V wall wart feeding the voltage regulator and it runs my fermentation chamber fan just fine. I'll double check though.

I actually bought a replacement fan, but now I'm thinking 'screw it', buy a real stir plate off Ebay or something. I'd hate to rebuild my stirplate and kill another fan

wehumble said:

I actually bought a replacement fan, but now I'm thinking 'screw it', buy a real stir plate off Ebay or something. I'd hate to rebuild my stirplate and kill another fan

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I would go ahead and replace the fan. I have been using my homemade stir plate heavily for years, and the fan keeps on going. I think it's probably worth it to replace the fan. But save yourself some money, find a computer repair shop in the yellow pages and call and ask if they have a fan you can buy, I got one for a dollar that way.

These fans are meant to push air - not wort - they're going to burn out regularly. I'm not an EE but if the power supply is pushing more amps than the fan is rated for, my guess, it's going to burn early.

ballegre said:

These fans are meant to push air - not wort - they're going to burn out regularly. I'm not an EE but if the power supply is pushing more amps than the fan is rated for, my guess, it's going to burn early.

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the amperage the supply is providing does nothing unless its not enough for it to operate then it simply.... wont operate..... its the over voltage that will burn something up..... No such thing as hooking up a supply with TO much amperage... the device will simply only draw what it can use......... Now if you try dumping 24 volts through a 12 volt fan then your going to have issues

You can quiet frankly hook up a 12 volt 300 amp powersupply to the fan and it will run nice and happy......

michaelm said:

the amperage the supply is providing does nothing unless its not enough for it to operate then it simply.... wont operate..... its the over voltage that will burn something up..... No such thing as hooking up a supply with TO much amperage... the device will simply only draw what it can use......... Now if you try dumping 24 volts through a 12 volt fan then your going to have issues

You can quiet frankly hook up a 12 volt 300 amp powersupply to the fan and it will run nice and happy......

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Yeah, this is true. It's over voltage that'll kill it. In A/C motors you can ruin them by not supplying enough current. I don't remember the math but it basically causes the motor to run really hot. That's not the case with DC motors though.

Of all the stir plates I've sold I have not heard of an issue with a fan dieing. <knocking on wood> I think you just got a bum fan, especially since you are using the LM317 voltage reg.

Derrin said:

Yeah, this is true. It's over voltage that'll kill it. In A/C motors you can ruin them by not supplying enough current.

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Whoops!!!! let me correct myself! You can ruin an A/C motor by supply less voltage than it requires, not less current. Less current will just pop the circuit breaker. Less voltage demands more current via ohms law and therefore fries the field windings.

I was thinking about this and it didn't sit right after I posted it, so I did a little looking and it has to do with using long extension cords that are not large enough gauge wire. The voltage drop can cause the motor to fry itself because it demands more current to run.

All of this has to do with A/C line voltage motors and nothing to do with stir plates so my apologies for posting info!

I've been successfully using an 115 v AC muffin fan with a light dimmer for several years now. No problems with overheating of either the fan or the dimmer. They don't even get warm to the touch no matter what speed I run it. I think the light dimmers are not rheostats or potentiometers so they don't reduce the voltage. Instead they switch on and off very rapidly. I'm not exactly sure how this affects the voltage or the current.