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Old 19th July 2005, 04:05 PM   #11
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agh it doesnt look right on that post..

____+
r |___fan+
___fan -
__r|__ground

r= resistor
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Old 19th July 2005, 04:06 PM   #12
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ahh i give up lol. it wont let me post something like that right
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Old 19th July 2005, 04:24 PM   #13
homer09 is offline homer09  Canada
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there is no way of properly calculating the value of the resistor you need to drop to 6V if you don't know what the fan draws at that voltage. maybe if u can find the datasheet for it, it MAY have the info you need...

but seriously, get a multimeter, even a cheap one shouldnt cost more than 25$. you shouldnt be building an amp without one!

oh and your resistor is simply places in series with the negative supply rail.

-ve supply rail > resistor > first fan lead > fan > second fan lead > +ve supply rail
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Old 19th July 2005, 04:30 PM   #14
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I know I know haha. I reallly need one. Lemme see if I can find what it draws real quick ( the sticker came off, Im gonna look in my box and see if I still have it.)

BTW: just so no one gets confused, my amp runs off of a single supply not split.

so, + on the fan goes directly to 32v + and negative goes directly to a resistor and then to ground?

btw heres pics of my amp
freq. responce help on mini amp
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Old 19th July 2005, 04:35 PM   #15
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I found it online, here it is, http://images.google.com/imgres?imgu...l%3Den%26lr%3D


Specifications:
Model: EC5010M05CA,
Voltage VDC: 5;
Current AMP: 0.16,
Input Watts: 0.80,
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Old 19th July 2005, 04:47 PM   #16
homer09 is offline homer09  Canada
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ok well now you know your values if you want to run it at 12VDC. but if you want to run it at 7.5 as mentioned before, the current draw will be different.

to connect things, yeah u got the idea. it doesnt really matter what side you put the resistor on, it will be the same.

so basically +ve rail > resistor > fan > ground.

the way you connect your fan will determine the direction it spins, so see what you want/works better.

to run at 12vdc:

20V drop. R = V/I > 20/.18 = ~110 ohms (wtv u have close to this is good)

power = IV = 20*.18 = 3.6W

if you want to use what u have, remember two 2W resistors in parallel are equivalent to 4W. and to get your 110R, you would need two 220R 2W resistors. these should be easy to find at this value.
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Old 19th July 2005, 04:49 PM   #17
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oops, just saw your post. well you now need a 27 volt drop, so correct the calculations to fit this new value, and use .16A for current draw.
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Old 19th July 2005, 04:50 PM   #18
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agh... sorry my bad, THIS is the one. And its current rating is a LOT lower.http://images.google.com/imgres?imgu...lr%3D%26sa%3DN


Ultra thin 12VDC Brushless 50mm case fan. Seven blades with plastic case. Thin 10mm design a real space saver. CE, TUV certification. SPECS: 0.06 Amps, 1.0 Watts, 4700 RPM, 9.4 CFM, 28 dBA. p/n MO N5010B2.
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Old 19th July 2005, 04:51 PM   #19
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haha so sorry for the mixup!
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Old 19th July 2005, 04:54 PM   #20
homer09 is offline homer09  Canada
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well it doesnt matter what fan. i taught u how to calculate the values, you should be able to determine the resistor you need for any fan as long as you know its current draw and voltage!

i taught you how to fish, so i dont have to feed you everyday
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