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.
For the most part, it is eye-safe. I wear sunglasses for the final test, and welding goggles while building becasue I am right next to the lights. More than a foot or so away, and it's not very dangerous for a short glance. Only when you are RIGHT on the LEDs does it really start to cause damage (I used a light-sensitive resistor and the threshold of a 3mW laser to determine what would cause eye damage).
Basically, if you don't have something right in front of the LEDs, and no one is looking directly at it, it isn't dangerous.
First off let me give John a thumbs up for the good work.
I have been reading this article over and over and cannot understand how Design News publishes a project that falls into a category of a flash light that can cause eye damage if looked at accidentally. This is not a novice project and Design News should considered not publishing projects of this type.
Nice project;it's great to see this lad working hands-on on this project. Perhaps a good follow-on project would be to design a switching regulator and avoid the power loss in the resistor bank. Keep up the the good work you've started.
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