Is 5v power supply strong enough for a stir plate?

Am putting together a stir plate i was wondering if 5v power is strong enough or should i look for something stronger?

Are you using a computer fan? If so, you might want to look for a 12V.

5v would just run at lower rpms right? And we technically don't need the fan running full blast, right?

Am using a 12v pc fan.

I have a 5v on my 12v fan right now it works but i am trying to scrounge up a 6v or 7v one to give a little more power. I tried a 9v one but it makes the fan spin to fast and throws the bar. I would say any supply between 5v and 9v will do the job.

Chrisl77 said:

I have a 5v on my 12v fan right now it works but i am trying to scrounge up a 6v or 7v one to give a little more power. I tried a 9v one but it makes the fan spin to fast and throws the bar. I would say any supply between 5v and 9v will do the job.

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Could you wire up a potentiometer between the power and fan to slow it down some?

am going to try to get a 7v supply see if i find one. my buddy has a box of old cell phone power supply but all those are 4.5 and 5v. i got two 5v power supply's from him.

I'm using a 5.5v USB cable with iPhone charger... I would like it a little stronger though.. 7 would be perfect

I would find a 12v and control speed with a pot. Variable speed is the schitz.

phenry said:

Could you wire up a potentiometer between the power and fan to slow it down some?

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I have one wired in. When i turn it all the way down with the 5v the fan dosnt spin and will not start spinning with the magnet untill i get near half way. The 9v and 12v that i tried made the fan spin to fast even with it turned down all the way. So my assumption is that a 6v or 7v transformer will probably be just right.

Here's a 6v AC adapter from radioshack for only $1.47: http://www.radioshack.com/product/index.jsp?productId=2049709#showFullReviews

I'm probably going to pick one up today to finish my stir plate and let y'all know how it works out.

phenry said:

Here's a 6v AC adapter from radioshack for only $1.47: http://www.radioshack.com/product/index.jsp?productId=2049709#showFullReviews

I'm probably going to pick one up today to finish my stir plate and let y'all know how it works out.

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That's a good deal am going to see if i can't find one if not am i'll pick one up when i get the rest of my stuff at radio shack

Man i just went through all my house and all i could find was 5v power sources oh well i guess its just one more expense on my list.

I have two cigar-box stir plates. Both use a 120 mm (4.75") fan. They each have a computer hard drive magnet on the fans and the magnets are epoxied with 5-minute epoxy. Because of the epoxy and magnets, of course, I cannot read the amp draw.

One has a 5.9v transformer and is just right. The other has a 7.x volt power supply and a potentiometer and the adjustable speed is great. With the potentiometer at full go, though, the 7.x volt power supply will throw a magnet from my flask. I tested it at a non-ridiculous speed for a week - just cuz - and it never threw the bar.

Different fans have different amp draws, too. So, the voltage of the power supply is not the only variable to consider. More amp draw = slower fan speed with same power supply. At least I think that's how the relationship works...

so most likely i will try to find and 6v or 7v am sure it will work.

It's MORE than enough. I use an 80mm 12V computer fan, and use a 5V DC, 0.7A blackberry charger. It supplies MORE than enough power.

I have to turn my potentiometer down to about 5-10%, otherwise I have a full vortex in the middle of my starter.

scottland said:

It's MORE than enough. I use an 80mm 12V computer fan, and use a 5V DC, 0.7A blackberry charger. It supplies MORE than enough power.

I have to turn my potentiometer down to about 5-10%, otherwise I have a full vortex in the middle of my starter.

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really? cause i have a 5v phone charger when i gave it a test run it seem i bit slow that's why i started this thread.

i have a selectable power supply - i've found that 9v works best for my stirplate based off of the "cheap and easy" build thread using some rare earth magnets and a 1.5" stirbar

If you only have the 5v, cut the fans blades off the fan and it will give you more oomph!

No fan blades = less resistance and a faster spin.

I would go with a 12V and use a pot, or even better, a pot with a voltage regulator (LM317). I had a 5V cell phone charger as the supply and it was hit or miss. With my 2L flask full, the 5V wasn't enough to spin the fan with the resistance of the stir bar (fluid resistance). If I picked up the flask, the fan would start spinning.

Now I'm using a 12V Rad Shack supply with the same 12V PC cooling fan and switched from a cigar box to a hobby box. I wired it up similar to this guy:

http://stirstarters.com/instructions.html

bratrules said:

really? cause i have a 5v phone charger when i gave it a test run it seem i bit slow that's why i started this thread.

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How many amps does your charger put out, and how many amps does the fan motor use?

Both should say. Most PC fans are like .1 Amp, the charger I used is .7amp. It runs very nicely at 5V.

Thanks for all the great info it really does help me out. I am really a numbskull when it comes down to electronics so the simpler the better. but one thing i do love about this hobby is all the diy projects!!!! but i stir plate is the perfect accompaniment to my frozen yeast bank.

scottland said:

How many amps does your charger put out, and how many amps does the fan motor use?

Both should say. Most PC fans are like .1 Amp, the charger I used is .7amp. It runs very nicely at 5V.

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well my fan states 12v-.020a
and my power source states 5.0v-550ma
for the outputs

bratrules said:

well my fan states 12v-.020a
and my power source states 5.0v-550ma
for the outputs

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So your fan draws twice as much power as mine, and your power supply supplies about 40% less. See where the issue is. See if you can find a PC fan that draws around 0.09ap. Most simple little 80mm fans do. Or find a power adapter that's 7v or higher

i have a 9 volt laying around the house some where but from what i have read some people say 9v throws off the stir bar. do you think this will be an issue?

i just found i had a 12v power source should i just use this or try to find something lower?

I'm using a 5.1v phone charger to run my fan (I need to check the amperage of my fan once I'm done using it) and I have just the slightest whirlpool forming at the top. I think a 6v power supply would work perfect with my set up.

So what does everybody think about using a 12v power supply with my setup? will it be to much?

bratrules said:

So what does everybody think about using a 12v power supply with my setup? will it be to much?

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Just go for it. If it doesn't work out, you can always change it out for another power supply. Just don't solder anything before you know what works.

ya i think am just going to use some quick disconnects!!! i hope to get done by this weekend. i just got my hands on a bunch of old hard drives so i got a good supply of earth magnets and i just need one lol...

Use a potentiometer so you can control the speed with the bigger power supply

Yeah am going to buy a potentiometer. but some people say that with 12v even on the lowest setting it still throws off the stir bar. but am still going to give it a shot.

Worst case, you can always use that 9v you have if 12 is too much

So i figure am just going to add a power jack on my project box that way i dont mangle any power supplys. also if one is to strong or to low i can change them with out rewiring!!!

Works perfectly for me. I run a computer fan with blades broken off using a 5v power supply. I don't even use any sort of speed control, it works great as is.

12v was waaaay too fast and 9v was too fast too.