We'll let you guys be the geniuses. We'll just buy the products. Jon Langeler Michwave Technologies, Inc.
> On Mar 11, 2017, at 1:40 PM, <[email protected]> <[email protected]> wrote: > > For the math heads, I was looking at the voltage solution and the current > solution and noticed that if I set the radical to zero, that is the point > where the quadratic blow up. I knew that was the minimum working voltage. > Anything above that and we are not a complex solution. > > So I set the radical (perhaps the discriminant) equal to zero and solved. > > -----Original Message----- From: [email protected] > Sent: Saturday, March 11, 2017 11:35 AM > To: [email protected] > Subject: [AFMUG] So anti-climatic > > This is what I was looking for when I started this quest. > > The formula is so simplistic, it almost seems like for the amount of work I > put into it it should be more complex. > > If you cannot see the image, there is the bottom line. > > If you have a device that uses a switch mode regulator, which is many things > these days because the are efficient, cheap and small, you have a device > that is essentially a constant power load. > > If you have to power that constant power load, (like an SM or a VDSL > ethernet line extender) over wires that have a significant amount of > resistance, like 1000 feet of 24 gauge twisted pair, there is a lower > voltage beyond which they will not operate. (I would say to not exceed > their input voltage either without zener protection). > > That voltage is: > > V(supply min) = 2 sqrt(PR) > > Where P is the power of the load. > R is the power wire resistance. > > In my case, I need 48.99 volts or more. >
