View Single Post
  #2  
Old 02-05-2009, 12:11 AM
JackW JackW is offline
News Editor
Platinium Techie
 
Join Date: May 2008
Posts: 1,040
Default

Quote:
Originally Posted by Jason View Post
- Volts : 12 VDC
- INPUT (Watt) 4.2 W +/- 10 %
- Current (Ampère) 0.35 A +/- 10%
I also read on the manual of the Gatewatch, each channel is designed to take
0.5 A
So I guess I have a problem about the Ampères when I will put both fans onto
one channel right ?
Not totally that simple. If the fans are in series then they will both get the full .5 Amperes, however if they are in parallel they will split it among them following a formula called a current divider (if the fans are the same it splits evenly). You'll have to see how your fans will connect (look at the pictures here: http://www.kpsec.freeuk.com/seriespa.htm)

Thing is though, if the current is the same, then the voltage will have to be divided over the two fans and the 2nd fan will be weak in comparison to the others. You'll also have to make sure there is enough wattage of power to run the fans, power = current * voltage. Whether its series or parallel you will lose out. Computers typically are organized in a parallel manner in regards to connecting components.

I suspect that the reason they suggest only one fan is that someone who is familiar with the system sat down with it and did the calculations. I'm not at all familiar with the device or any of that, I'm just a computer engineer so I get taught all of this. Get a multimeter and try to figure out why its not working.

By inspection I suspect there will be 2 amps that gets divided over the 4 rails that should allow you to connect 5.7 fans to, but what you'll probably have to do is connect all of the leads and then make your own divider circuit. This has problems, namely can the cables take 2 amps. Honestly there is probably no easy solution from what I've been taught, but I'm not an expert on the system.

Cheers,
Jack

Note: Sticky'ed so it doesn't get lost off the first page.
Reply With Quote