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Wiring Computer Fan(s) to Run on 120V A/C

  • by Azureblue
  • Apr 09 2009 02:06 PM
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Posted 09 April 2009 - 02:06 PM

I have received a lot of Private Messages asking how I converted two computer fans to run on 120V A/C power (your standard wall plug-in) used in my first grow.

First off, let me say that I am not an electrician (not even close!), just a do-it-yourself'er who likes to tinker. I am providing one method that has worked for me. Please feel free to correct me if I have made an inaccurate statement and/or suggest a more efficient method.

The main reason why I choose to use computer case fans for my pull through exhaust setup is because they are extremely quiet, and stealth has always been very important in my grows. The dual ball-bearing fans are particularly hushed.

To start, pick up a nice dual ball-bearing computer fan. You can get great fans cheap from tigerdirect.com, though any computer fan will work for the purpose of this writeup. Fans like this one can be had for less then $20:

Ultra Performance 120mm Case Fan - Dual Ball Bearing ULT40135 at TigerDirect.com

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Now, find out how many amps the fan will draw. If it doesn't say on any of the packaging, go down to Radioshack and find one of comparable size (80mm, 120mm, etc.) and see what the amperage is. Then, go down to Radioshack and purchase an a/c to d/c (alternating current to direct current) power adapter. It just looks like a cell phone adapter. It's like $20:

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12VDC 1500mA AC Adapter - RadioShack.com

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Make sure you get one that is big enough to support your fan(s). If each fan requires .5A (or 500mA) then get something that will handle it. For example, if two fans draw 1amp (or 1000mA) total then buy a power adapter that can handle 1.5A (or 1500mA) and you'll have more then enough.

Alternatively, if you are trying to save some money, you can sometimes use the old power adapters (from old cell phones, etc.) you have laying around your house. The method is the same, though the positive and negative wires may not be identified. You must also ensure it has adequate amperage, etc., as I mentioned in the paragraph above.

Then, while you are there, purchase some "butt" connectors. You can ask them for help if needed. They look like this:

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Cut off the connector at the end of the cord on your power adapter. On both the adapater and fan(s) strip the plastic off the last inch of all wires. If you don't have any tools you can do it with a knife (be careful!). They make a tool just for this step, a wire crimper, which helps a lot and is probably already in your garage:

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Once you have about an inch of bare wire, slip the adapter end into one side of the butt connector and slip the fan end into the other. Crimp (compress) the connector down with some needle nose plyers. If your fans have three wires, a yellow, red, and black, splice the yellow and red together. The yellow is a switch wire and can be used to turn your fan on and off, but that won't be an issue for you. This way it will run any time it has power.

If you aren't sure which wire is positive on your adapter, touch the adapter and fan wires together while the adapter is plugged in (be careful never to touch exposed wires to your skin when plugged in!!). If the fans turn in the correct direction, you are good to go. If they turn in the opposite direction of what they are supposed to, you have it backwards.

Once everything is crimped you should be good to go. It will look something like this. Notice the little connectors at the bottom of the picture and how the red and yellow are spliced together:

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Good luck! PM me if you have questions.

Edited by Azureblue, 24 April 2009 - 07:05 PM.

Replies (108)

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Posted 09 April 2009 - 10:23 PM

This is sweet. I have been wondering about how to wire some of these up.

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Posted 09 April 2009 - 10:35 PM

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Posted 09 April 2009 - 10:50 PM

LOL o yea :hide:

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Posted 10 April 2009 - 03:20 PM

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I am aware of that option (have a lot of experience in that particular field) and that is way too bulky for my cabinet grow!!

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Posted 10 April 2009 - 04:34 PM

I am aware of that option (have a lot of experience in that particular field) and that is way too bulky for my cabinet grow!!


as well as burning from 300-600 watts to power your two fans! :smoking:

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Posted 10 April 2009 - 04:39 PM

as well as burning from 300-600 watts to power your two fans! :smoking:


doubt it, unless you have something to use that power, where would it go? maybe if you had a computer with hard drives, motherboard, CPU etc. to power, but if you only have two small fans, they're only going to use the power to turn the small fans

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Posted 10 April 2009 - 04:45 PM

This tutorial is way overdue, +rep!!!!

STICKY!!!!!!!

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Posted 10 April 2009 - 04:57 PM

i had an elec engineer try and tell me that a computer consumes a huge amount of power when switching on, so much so that he recommended leaving it on 24/7?

i thougth it was wierd but i dunno, i like the radioshack route better unless you have a junk power unit lying around (which i do wait a sec, need to think that one over)

In a pinch, you can buy a 3 pack of 6V batteries at walmart for 4 bucks and power them for almost a week per battery, depending on the voltage of the fan

Edited by rudar, 10 April 2009 - 04:59 PM.


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Posted 10 April 2009 - 05:33 PM

i like the radioshack route better unless you have a junk power unit lying around (which i do wait a sec, need to think that one over)


indeed. that's really what I meant, if you have one lyin around it's a free power source and you can hook plenty of fans up to one quite easily. of course it's always better to use something specifically made just for the fans

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Posted 10 April 2009 - 06:19 PM

Nice tutorial, I could have used it last grow.

-C

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Posted 10 April 2009 - 06:29 PM


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Posted 10 April 2009 - 06:51 PM

you can also use old power packs from video games and the such electronic items, most run off 12vdc anyway, save a few bucks also, just look on the back of the pack for the rating in volts and milla amps. Wire it up. Ones from old cellphones chargers work also.

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Posted 10 April 2009 - 06:55 PM

Hey, thanks for the compliments! :D

I wanted to share this with my fellow Blades because it has been a great, efficient fan solution for me. The dual-ball bearing fans are SO quiet. If you take about 4-5 steps away from the growbox in a totally silent room, you can't hear them anymore :D. Even when you are right next to them it sounds more like a distant appliance, your ears really don't follow it like a loud sound. Stealth is a major priority for me, and this really fit the bill.

Anything I can do to give back to the Grasscity.com community that has helped me so much makes me very happy :hello:

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Posted 10 April 2009 - 07:49 PM

How are those 2 fans working for you, I currently have a dresser cabnit grow, i have 4 - 3inch circle vents with no fans to them, I'm going to try the fan method, I was wondering if there is a way to adjust fan speed on what you setup, I remmber on my old computer i had a adjustable knob for fan speed to 1000rpm-9000rpm. I'm trying to keep my heat under 90 im at like 82 but i keep my window open and its still cold so come summer i will have a problem,

well i just wanted to know how those 2 fans worked out, id set 3 to push out air out and 1 to pull in fresh air,

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Posted 13 April 2009 - 02:06 PM

How are those 2 fans working for you, I currently have a dresser cabnit grow, i have 4 - 3inch circle vents with no fans to them, I'm going to try the fan method, I was wondering if there is a way to adjust fan speed on what you setup, I remmber on my old computer i had a adjustable knob for fan speed to 1000rpm-9000rpm. I'm trying to keep my heat under 90 im at like 82 but i keep my window open and its still cold so come summer i will have a problem,

well i just wanted to know how those 2 fans worked out, id set 3 to push out air out and 1 to pull in fresh air,


They have worked out great for my cabinet grow so far :D

My growbox dimensions are approxximately 3' x 2' x 2', so 12 square feet. They have proved to be enough to not only work functionally as a pull-through exhaust system but also kept up with the added restriction of a carbon filter.

If I had to do it all over again, however, I would suggest using the biggest computer fan you can find. It is easier to mate filters, etc., up to a single fan, versus two like I have used. I can't complain though, I've had great luck with these fans so far.

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Posted 24 April 2009 - 07:12 PM

Update:

The setup in my original post utilized two 80mm fans. I decided to upgrade recently since I am growing on a slightly larger scale now and need the extra airflow. I upgraded to the fans that I recommended in my original post. They are two 120mm dual-ball bearing computer case fans that are rated at 80cfm each (for a total of 160cfm):


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I used the same Radioshack power adapter that I pictured and linked to in order to power both fans. It is working great and providing more then enough power!

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Posted 24 April 2009 - 08:15 PM

You can usually find old AC adapters at Goodwill for cheap. Keep in mind also that most PC fans will run at a range of voltage (usually somewhere around 5V-18V). Depending on your noise tolerance, you can overvolt or undervolt as you see fit.

Also, it is worth noting that an AC adapter will put out its specified voltage at full load. If operating at less than full load, there is a good chance you are getting extra voltage. Use a multimeter to see how much exact voltage you are delivering to your fan and make any necessary adjustments accordingly.

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Posted 24 April 2009 - 08:33 PM

you connected them all to the same adapter?

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Posted 24 April 2009 - 10:04 PM

I'm running two 80mm Panaflo low speed fans which have a power spec of 100mA @ 12V each. Funny thing is they draw less than rated since the 200mAh 9V wall wart I am using is putting out a voltage of 10.5V. Rated load for those fans is on the conservative side I think.

Wall warts come in a variety of sizes. I have one that is rated for 3A @ 12V. Always hang on to these when tossing old electronics. If you're looking for some, hit up your local goodwill. They seem to have a bin of these by the electronics. Can be had on the cheap.




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