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Topic: <SOLVED> Another Noob Power Question (Read 831 times) previous topic - next topic


Oct 18, 2012, 05:14 am Last Edit: Oct 18, 2012, 06:13 am by NobleNoob Reason: 1
If you start out with a regulated power source, say 35A of 12V from a converted ATX power supply

In a simple voltage divider as I understand it anyway,

                      R1              R2
+12V        o----\/\/\----o----\/\/\------o  GND
            V1               V2                

How do I find out what values for R1 and R2  if  V1 = 12V and V2 = 7.5 @ 2.0 Amps

R1 = ?
R2 = ?
V1 = 12V
V2 = 7.5V

And since the V1 = regulated 12V and isn't supposed to fluctuate (too much)
would I not get a fairly constant value from V2 ?

This would allow for powering a couple of legacy devices that require a regulated 7.5 V as well as powering the arduino itself at 7.5V instead of 12V making arduino regulator work cooler.

I'm gonna burn up so much stuff... better tripple my parts order!

Thanks guys...


You can't use a voltage divider to power a load, since the voltage out depends upon
the load current. IE, the usual formula for the v.div assumes no load current.

One solution is to use a voltage regulator, but something like 7.5V @ 2Amps is not easy to
produce. You should probably look for some kind of dc-dc converter that will push 2A
and where you can set the voltage out.


Oct 18, 2012, 06:13 am Last Edit: Oct 18, 2012, 06:14 am by NobleNoob Reason: 1
I knew it!, I just knew it, just like that dream of winning the lottery, so real, so vivid, until I woke up :)

I havn't gotten my starter kit yet and am going nuts  :smiley-mr-green:

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