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05-02-2007, 10:29 PM
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#16
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Reefless Reefer
Join Date: Jun 2002
Location: Durham, NC
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as long as the amperage of the two fans does not add up to more than the amps that the adaptor puts out is. the fans should have a rating on them volts and amps. find a PS that matches the volts and the required amps. usually not that hard. fans do not use that much power.
run them in series. this keeps the volts constant.
G~
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05-03-2007, 04:33 AM
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#17
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Little Fishy
Join Date: Apr 2007
Location: Monrovia, CA
Posts: 53
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connect the fans in 'paralell'.
i.e. connect the rexds togeter and the blacks together.
Or if there is no colors, then it might have plus and minuses, connect the plusses and then connect the minuses..
hth
bill
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05-03-2007, 09:10 AM
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#18
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Join Date: Mar 2006
Location: spartanburg, south carolina
Posts: 4,940
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OK, I'm confused. One recommendation for parallel, one for series. Which one should I use or can I do either? Any benefits of one over the other? Can I wire in an "on or off" switch using one of the wiring methods?
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05-03-2007, 09:51 AM
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#19
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Little Fishy
Join Date: Apr 2007
Location: Monrovia, CA
Posts: 53
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Paralell. Runinng them in series will reduce the fans voltage in half for two fans, and that would reduce the fan speed to half.
Series would be wiring one fans positive to the other fans negative, then connecting the first fans positive to the wall wart positive, then the second fans negative to the wall warts negative...
This would be wrong.
Geoff, can you please review your reccomendation and or clarify it for us.??
Thanks
bill
btw: If you did it in series, nothing will blow up or burn up, just not run as fast, and if you too many fans, then there could be an overheating problem.
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05-03-2007, 10:08 AM
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#20
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Reefless Reefer
Join Date: Jun 2002
Location: Durham, NC
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i am prolly wrong. i always need to grab my volt meter to double check myself.
G~
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05-03-2007, 11:03 AM
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#21
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Little Fishy
Join Date: Apr 2007
Location: Monrovia, CA
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Well, we need a tie breaker then. Anyone else care to chime in and break this tie???
But like I said above, you can try both ways, nothing bad will happen, either way.
Let us know what happens and which way you go with??
Bill
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05-03-2007, 11:41 AM
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#22
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senior member
Join Date: Jan 2000
Location: Walnut Grove, SC, USA
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Quote:
Originally Posted by Geoff
run them in series. this keeps the volts constant.
G~
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Parallel please, this will allow the fans to run at full speed as per specs for the fans and will allow the transformer to run as designed.
HTH
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Wise men speak because they have something to say; fools, because they have to say something. -Plato
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05-03-2007, 11:58 AM
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#23
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Little Fishy
Join Date: Apr 2007
Location: Monrovia, CA
Posts: 53
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And there ya go. The winner by a decision, Bill.
Yup, the series would devide the voltage supplied by however many devices you put into the series circuit.
you will still need to make sure that the number of fans is considered in the total current available, i.e. each fan will be reated for a certain amount of current, add up all the fans and devices, and make sure that you are not exceeding the total amount of current available from the power supply.
If you do exceed that amount, things may get warm, even hot, and even worse...
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05-03-2007, 04:16 PM
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#24
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Join Date: Mar 2006
Location: spartanburg, south carolina
Posts: 4,940
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Thanks for the replies everyone! I just checked my fans, I have two of them and they are rated at 12 volts and 0.15 Amps each. So I need to get a power adapter that can handle at least 0.3 Amps, is that correct? I'm not very good at math, is that 300 milliAmps?
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05-03-2007, 10:47 PM
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#25
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Little Fishy
Join Date: Apr 2007
Location: Monrovia, CA
Posts: 53
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yup that would be 300 milliamps, but just find something that is around a 1 amp, that way it will be good for anything later on down the road.
But if you have stuff laying around the house, like old adapters from cell phones or answering machines or shavers, etc, you can use anything that is above the .3A requirement.
Good luck
(ALSO, check to make sure that it is 12VDC, not AC. Just to check)
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05-04-2007, 09:12 AM
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#26
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Join Date: Mar 2006
Location: spartanburg, south carolina
Posts: 4,940
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Thanks for the reply Bergovoy! Yes, the fans are 12V DC, so I will be getting an AC adapter from Radio Shack most likely. How does this one look?
http://www.radioshack.com/product/in...entPage=search
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05-04-2007, 10:33 AM
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#27
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Reefless Reefer
Join Date: Jun 2002
Location: Durham, NC
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YES, YES, I WIN, I WIN, I was Wrong!!! 
i told you i always had to double check myself. that silly PVI pyramid gets me all of the time.
G~
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05-04-2007, 11:41 PM
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#28
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Little Fishy
Join Date: Apr 2007
Location: Monrovia, CA
Posts: 53
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That will work, it is on the pricey side, but it will work.
Do you not have a surplus store in your area? Or no left over electronics in the house.
If that is what you go, go with it, it will work.
Good luck
And geoff, better luck next time...
Bill
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05-05-2007, 08:32 AM
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#29
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Reefless Reefer
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G~
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05-06-2009, 02:23 PM
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#30
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Little Fishy
Join Date: Apr 2009
Posts: 71
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Sorry to revive this thread but I had an additional question.
If running two fans in parallel, how could I wire in a rheostat to slow down the fans at night? Is there any resistors or special circuits needed for this modification?
Also, is it possible to wire four fans together with a single rheostat? The fan ratings are 12vdc .12 amps. I know I would need a 12v power supply with AT LEAST .5 amps (I have a 1 amp power supply).
Thanks guys.
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