Great post. I am truly gratified to find a student, not only interested in engineering, but one who is resourceful and obviously up to a challenge. Great work. The project is also very useful. I don't know if you wish to market this design and device but I certainly feel it would be a good candidate and the sales effort might be very interesting.
sorry I took so long to respond, I haven't checked this in a while. I could have used four LEDs, but the minimum voltage to keep up output is 3V, so if I run four, it would only work as long as its above 12V. A deep cycle battery will drop the voltage a bit when a load like that is applied, and though ohms law will drop the current going to them based on the resistors, the effect would be way more significant if each gets <3V.
As for a driver circuit, I could have, but I was pressed for time initally, as I had intended to bring it to a gadget competition at a camp I was attending. Unfortunatealy, the LEDs didn't ship in time, and I didn't see much of a need to redesign. Another light I made just a few days ago using two LEDs does use a driver circuit. As for calculating the resistors, each LED has a frop of 3V, and thus for each LED, just subtract 3V from 12V, then use ohms law for 3A. I ran three, thus a drop of 9V, leaving 3V. I needed 3A, thus 1ohm. two would leave 6V, thus needing 2ohms, and one would leave 9V, needing 3ohms four would leave 0V, thus 0ohms, but leaving the problems mentioned before.
As for the safety issue mentioned, most of that was precautionary. From more than a few inches it won't burn. Becasue it has a ~120 degree spread, the power will very rapidly dissipate, so it's NOT like a laser, but is powerful enough to distract or irritate someone from afar. Basically, I just meant don't shine it at cars or in peoples eyes. It, and almost all things should just be treated as though they are more dangerous than they really are.
And finially, does anyone have any advice on easy to build 3D printer extruders, specifically, something light that doen't require fabrication access (no milling, latheing (lathing?) 3D printed parts, etc.), just hand tools and such? I'm building a cheap 3D printer/wax CNC device, and the only problem I haven't fixed so far is the extruder, mainly becasue it will likely be fairly expensive (I'm looking for <$50, though), and thus I don't want to experiment more than I have to, as that will get expensive fast.
Good Job Duffy ! Keep your thinking cap on...innovate or perish!
Regarding "dangerous" LED light; Anyone who works with LEDs has inevitably received 'retina burn' from looking directly at a lit source. Being an evolved human, the typical person quickly looks away to mitigate the effect....which is annoying at worst. (seeing spots)
"it hurts when I look at the sun"
"so, don't do that, stupid."
Here's a biological safety report from Lumileds for an LED comparable to the one John used. www.philipslumileds.com/uploads/292/AB81-pdf
Result: Low risk to damage the eye from white LEDs. I've read elsewhere that exposure to Risk group 1 is comparable energy-wise to looking at the horizon line on a bright sunny day at high-noon in the desert, without sunglasses. In other words, peanut butter is probably more dangerous.
That said, good call on the sunglasses/welding mask...those 'after-image' spots are truly annoying, especially if you're trying to work a solder iron!
Note: blue or royal blue LEDs present a higher biological hazard because of the narrow bandwidth and high energy content of blue light...so if you're developing a remote phosphor system or a weaponized blue LED stun light, keep your welding goggles handy.
In response to the nasty criticism about this being so very dangerous. Most of the readers drive cars, which are far more dangerous than this flashlight. Almost everything requires a bit of wisdom and good judgement to use. The safety rules designed to protect drunks bent on self destruction are a needless burden on most of society. What I am referencing is the european safety regulations for electrical equipment, by the way.
At some point an individual must take responsibility for the results of their actions, and a big part of that responsibility is understanding what one is doing. I know that is offensive to those who abhor personal responsibility, go ahead and be offended.
Those who produce my designs are confident in my level of responsibility, and know that I will not deliver a design that will not meet the project requirements. That would be a big risk if I were not responsible enough to assure that the design was adequate. Certainly there are many other engineers in a similar position, who are responsible for doing their job correctly. Those are the good engineers, the others need to have fifty people check their work for errors, oversights, and other types of goof-ups.
I disagree with the statement that Gadget Freak articles are just for novices. I'm a retired electrical engineer and I don't miss a single one. Even an experienced engineer can sometimes learn something.
In an age of globalization and rapid changes through scientific progress, two of our societies' (and economies') main concerns are to satisfy the needs and wishes of the individual and to save precious resources. Cloud computing caters to both of these.
For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This discussion will examine what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.