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Old 10-15-2013, 04:54 PM   #1
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Default weak power supply for stir plate?

So I just finished making a diy stir plate and everything seems to work great other than the speed of the fan is very weak. The power supply specs are:

Input 100-240V, 0.2A Max
Output 12V, 500mA

I thought in all the research I read that 12V would have been plenty but I don't know that much about electronics. Could this be the cause of the slow speed?

Only thing set up between the supply and the fan is a 25ohm reostat and a rocker switch.

Thanks!

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Old 10-15-2013, 07:54 PM   #2
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I bought one of these motor controls from ebay and a used 12V DC Wallwort power supply from Goodwill. IMO, it's a perfect speed control for <$15. 12V will result in a higher fan speed than needed for a starter.

http://www.ebay.com/itm/12V-40V-10A-...item4614549bf4

img_1942.jpg

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Old 10-15-2013, 08:58 PM   #3
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My questions was about my current power supply being too weak, not too strong. With my current set up it barely spins my fan at all and I'm not sure why because it says on the adapter that it is 12v.

Neat looking setup BTW!

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Old 10-15-2013, 09:04 PM   #4
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Quote:
Originally Posted by STL_Lucas View Post
....Only thing set up between the supply and the fan is a 25ohm reostat and a rocker switch.

Thanks!
What voltage are you applying to the fan?
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Old 10-15-2013, 09:45 PM   #5
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Quote:
Originally Posted by STL_Lucas View Post
My questions was about my current power supply being too weak, not too strong. With my current set up it barely spins my fan at all and I'm not sure why because it says on the adapter that it is 12v.

Neat looking setup BTW!
Do you have a meter to measure the voltage to the fan with and without the pot inline?

Are there multiple output wires on the power supply?
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Old 10-15-2013, 10:09 PM   #6
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I tested the fan with the power supply directly before I hooked it up to the pot and it was the same speed. I don't have a meter to gauge the voltage. The Power supply has two wires and the fan has three. I belive the middle wire on the fan is not hooked up to anything and was not needed.

I just noticed the power supply says AC Adapter on it. Is this the problem? Should it say DC Adapter?

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Old 10-15-2013, 10:13 PM   #7
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Depending on the fan .2A could be the problem. 12V is plenty, but that current rating may not be sufficient for the fan. Can you post a picture of the sticker that is over the motor housing of the fan?

Also, AC adapter is normal. It is an AC to DC converter. It converts 120V AC to 12V DC

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Old 10-15-2013, 10:14 PM   #8
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Thats what I thought. I'll post a link for the fan.

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Old 10-15-2013, 10:17 PM   #9
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12V AC Adapter


Primarily used to power up fans. Each adapter can power up to 4 of our fans.
•Input Voltage (nominal): 100-240VAC
•Input Current (max): 0.2A
•Output Power Rating: 6W
•Output Voltage: 12V
•Output Current: 500mA
•DC Output Connector: 2.5mm Barrel Plug
•DC Output Cord Length: ~5 feet
•1 year warranty


Link for the fan is:
http://www.microcenter.com/product/3...eries_Case_Fan

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Old 10-15-2013, 10:26 PM   #10
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That fan is rated for .24A. So that power supply isn't capable of fully powering that fan. Do you have an old wireless router or any other 12 volt power supplies laying around? That is what I use for mine. It provides 12V at 1.2A and works great. To test and see what the fan can really do you can hook it up to a computer. It will get the full voltage and amperage it wants then and you can compare that to what you get out of your little power supply.

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