Ever seen this done??

2old2care · Posted: Thu Oct 28, 2004 11:11 pm Post subject:

Okay, Assuming your regulation is in the hub...you could do this...Let's finish the math.

12V minus 7.5V = 4.5V (called e-drop caused by the resistance to current flow) times 1 amp = 4.5Watts requiring a 5 watt resistor and 4.5 watts of heat inside your case.
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Sally · UberTweaker Joined: 31 Mar 2004 Posts: 1158 Location: WA

alrighty, my apologies 2Old

I consulted the EE major (*brother)

Basically: V=IR ...so as your current (I) is resisted (lowered) and your resistance (R) is increased, your voltage may or maynot change depending upon if the values of I or R are equal

Here's his summation:
sandnessizer: basically- to keep voltage constant, raise resistance and drop current or vice versa
sandnessizer: like in a car, if the amp is huge and draws a lot of current, and the load (speaker) stays constant, then the voltage drops (lights dim)
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JayDubya · Posted: Thu Oct 28, 2004 11:39 pm Post subject:

2old2care · Posted: Thu Oct 28, 2004 11:40 pm Post subject:

That's why the regulation must be in the Hub or as load changes the voltage across the resistor will change. And the poor things getting different voltages at different loads. Semiconductor is required to "fix" a voltage.

Anyway, where's your bro going to school?
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Silicon Skum · Posted: Fri Oct 29, 2004 10:09 am Post subject:

Dunno why I did'nt think of this before, but I'm using something to drop a 12V psu down to 9V for my router. A CHEAP car cigarette lighter socket / 12v aoutomotive power adapter thingey. It has a built in regulated circuit to suply between 3V and 12V. The beter one can supply 1A wihout ANY problems.

something like this (but there are WAYYY cheaper ones out there!):

http://www.bestbuy.com/site/olspage.jsp?j=1&id=1077626358357&type=product&ref=03&loc=01

http://www.electronic-cn.com/inverteradapter.htm (slow site)

Just hack the thing apart and connect it to the 12V line of the computer. Simple.

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JayDubya · Posted: Fri Oct 29, 2004 1:32 pm Post subject:

Hey, i've got a few of those somewhere. Sweet.

2Old, i see your point now. I've got alot of testing and experimenting to do. I'll most definately put a fuse in the line to save the $5 hub

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2old2care · Posted: Fri Oct 29, 2004 1:39 pm Post subject:

JayDubya · Posted: Fri Oct 29, 2004 1:43 pm Post subject:

Not the ones i was going to test them on. A p1 and 3p2 psu's. Hardly worth the storage space to keep them . . . . better to be safe than sorry though
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2old2care · Posted: Fri Oct 29, 2004 4:27 pm Post subject:

Okay tear em' up then, Stumpy J. <--WTF's up with that?

Just watchin' over my team mate's back...we'll need the good one's when we make our charge on the "top two folders"

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