The Perfect Tech flashlight


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I have the opportunity in an Engineering Tech Class to build my own flashlight with LEDs. What would be the perfect flashlight? One narrow-beam LED for shows, and three for set-up and strike using Selectable modes? Tactical Switch, or Mag-light style? How many LEDs should I put in?

I know this draws on previous threads, but I wanted to start a specific topic on building the perfect flashlight


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light wieght.

the one i posted about recently, i dropped it on my watch and craked the glass. mind you it was only about a 12" fall but still, now i have to go buy another watch, yay for paychecks....


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I think the number of LEDs comes down to how bright the LEDs are. one really bright one could probably do the job of 3 or 4 dim ones. I think another consideration would be the reflector (if the LED isnt the kind with a built in one), if you are trying to cram too many LEDs in, I dont know how easy it will be to make an effective reflector. Just a few thoughts.


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Premium Member
Reflectors intrigal to both assembly and as seperate at times are to be had, as with constant advances in LED technology.

Fixtures such as the Color Blast have individual reflectors on the individual - what do you call them lamps, even if not really. While a wash fixture, there is probably 80 MR-8 sized of them within one assembly. Remember that the more compact the point source of light within a reflector, the more efficient that reflector can become in focusing the light beam.

"Myth Busters" showed in breaking the myth something in the past about a Fresnel Reflector as mis-stated in being called a Fresnel reflector specifically, as used in burning down some ships. They prooved for the most part that by way of number of individual reflectors, you could not get a efficient enough focus of light to do the work.

In real world terms, the more compact and pin point that source of light within a reflector, the more efficiently the reflector can focus the beam of light. You can at some point place a hundred LED lamps within a reflector and not get a good beam of focused light. It will have huge output, but the efficiency of the reflector will be nominal. On the other hand, you can put one LED and while more efficient potentially than 100 lamps within a reflector, two LED's will be twice as bright within reason given the exchange of reflector efficiency verses double the output for 1/2 the square size in larger filament or source of light. Four lamps than in being double the area would have four times more light but only double less efficient a reflector. There is a balance somewhere in lamp output based upon numbers in making for a larger point source of light, verses using the reflector - director of light given off most efficiently.

I'm stating this because there needs to be a balance in quantity of sources thus the quality of what's reflected over quantity in general. LED lamps as they develop are starting to have nuances between something in general and something specific just as if lamps.

A year ago, a vendor rep. from Philips took great pride in some LED lights he powered up in demo while blinding me that they were bringing to market in coordination with another company. On the other hand, just this week I saw a news article on a industrial lighting news letter E-Mail, probably which noted the brightest yet in LED technology for an individual lamp. This Philips lamp now even if bright for it's day now it would seem is old hack. This all as opposed to some LED cyc lights I saw early on in products new to the market that were so dim they would be hard pressed to light a studio theater cyc sufficiently.

If of help, balance the number of sources with the accuracy of the reflector when it comes to the beam of light. Certainly a wash beam of light will be able to have a larger focus point than a spot of light. Much less two lamps will be often brighter than one, but still base that off reflector efficiency by having something that's now 1/2 the square of it's filament/arc source - point source of light as it plays a factor into reflector design.

Than we get into reflector design, and color temperature of LED over output and life as I'm sure it's stil going to be a factor in what's the most bright either seemingly by way of color temperature or as exchanged for luminous output but a dimmer beam of light, or life in general.

A flash light ha? What a great project to study what will be the next generation of technology from. Give kudo's to your instructor for this challenge in studying stuff, as it would be a good thing to learn lots about.

As trade off in fixture/lamp design, I thus present you the challenge of more output by way of quantity, verses efficiency by way of both lamp and reflector efficiency of point source, given also differences specific to individual reflectors.

Good project.

Based upon this micro technology, perhaps a solution might become some sort of internal reflector LED lamps that already are say 20% more efficient in directing the light beam that otherwise is absorbed. Read into the Osram HPR lamp for that internal lamp reflector concept. Than putting a balance of sources of the most efficient of them verses a single point source of light into a reflector that in a design curve has the most efficiency verses output balance. Let's say 16 high efficiency LED lamps with already internal reflectors on them within a reflector overall and best of quality fixture reflector for the assembly. Than if possible, go for high color temperature lamps to throw you over the top in it's own balance of high luminous output verses what seems brighter by way of color temperature.

Perhaps given the filament of a LED can be smaller than that of a halogen mini-lamp, the reflector size can also be reduced, and given some sort of adjustable platform the lamp/reflectors mount to, you can have smaller reflectors, yet also focus or flood multitudes of reflectors into one Mag Light assembly. In going back to the Myth Buster's example, it was not possible given loss in reflector, much less accuracy of individual verses individual reflectors to focus a beam of light efficiently enough. Were it one reflector, possibly. Given not only internal reflector lamps, perhaps four per reflector, and a few mini multi-lamp reflectors on a adjustable focus mounting to them, you than might get something approaching that of a laser in output and efficiency of light beam. This in addition to the most efficient of lamps to date. This while if anything similar to a filament lamp, operating ever so slightly say 110% over rated voltage for greater still output on the lamp.


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This is something to keep in mind- as the batteries wear down, the LED's will become dimmer of course, but- inorder to preserve batery life when they are fresh and get the most out of older ones, make it dimmable. Use a three way switch or something with three levels- that way, you can use the lower level when your batteries and the higher level when they are older and you will light that is practically even when the batteries are new and when they are old.


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AFAIK (and I should because a company a friend is working for is developing LED fixtures for use in the entertainment industry) most LEDs have reflectors built in, and generally throw their light forward. From experiments, I can say that LEDs do not get much brighter with a second reflector. What I CAN tell you is putting a LED lens in front of it DOES help. They come in all different shapes, sizes and degrees. It's like popping a lens on a source four, you can get different kinds. That'll keep the light focused (or unfocused) even more. What I would suggest is a on/off switch, and a secondary push and hold button like some flashlights have. That way, it goes on and stays on without the need to screw anything (quite you immature brats), and if you only need it for a second or two you just push the other button for the duration. Depending on the type and amount of LEDs, the batteries required will differ. Be aware that with higher wattage LEDS (believe it or not, they are available commercially at up to 20w PER LED!) may require a specialized power supply or circuit board (but with a simple flashlight I would think not), which can create heat. The LED light does not give off heat but I can say from experiance the connection to the power source sometimes does.

I would think a neat feature would be a switchable white/blue/both flashlight, or even blacklight/white flashlight, if they make blacklight LEDs. Of course, plain white is fine.

Just my $0.02 (CAD)


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Wow! You guys got me really pumped for this project. Thanks for all your input and keep it coming. I can't go at this alone and I'll be sure to post progress.


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Make sure it is durable. It should survive a considerable fall if it is the perfect tech flash light. Also make sure it is handy. It needs to not be an issue when on your belt going up ladders and such. 7C cell mag lights are. They don't even make those anymore and I think I know why.


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Premium Member
Anonymous said:
I'm guessing you meah NiMH, not NiCD, because nicads are the ones that get a memory. to me, nimh and li-ion are the only batteries I would even consider buying for anything. I don't know what the mah and stuff are for certain weights or anything per type of battery, maybe nicads get way more mah than a same weight nimh, but really, they are batteries, you are adding oz, not lbs!

and the batteries are likely removable, so he could design his flashlight on whatever and still be ok whatever he goes with, right? nuances might change but the overall functin shouldn't be that different wit ha different power source. as long as the watts and current and voltage and stuff are the same anyways.

a few nice featres might be a plug for charging batteries in the flashlight (you can pull them out to charge, or plug them in to charge), lights or a led strip like a VU meter that show your battery level when you first turn on the switch, and something so you can make custom gel frames and use rosco (or lee or gam or whatever) gel swatch book gels on the flashlight! :) That and a CTO gel and you can get maybe an estimate of what a gel will do, not that great, sorta pointless, but someone might get a kick out of it!

I'm speaking in general in batteries here for what extent I know c.1986 and Makita corcless drill batteries at last study on my own extent of knowledge in class. They quickly after a mistake in design lost that bit of bad technology in memory chip. Intent on my part was to state the difference in high output verses long life batteries in general. But I do stand as corrected in different forms of NiCad / NiCD verses NiMH batteries.

Still the intent is the same and thanks for the correction, perhaps in a later post some more info into the four groups of batteries including alkaline presented for this design will than be of use. NICAD/NIMH/Lithium/Alkaline for power source.

As for recharger, that's extra weight and while it might be worth it, might also not in both space and need.

I'm very interested to see a lot of design concept in this project an hope it continues. I for one even if not working on it am also learning a lot from it.


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LX-88. Good idea for a project. Just a point to keep in mind, that some one mentioned in passing, LED's need an electronic control circuit. If you are using maybe one or two lower power LED's you can could get away with just a resistor to limit current. However if you are using super bright LED's which you would really need for a torch you need a circuit that supplies a constant current. This protects the LED's but also means the light output won't get dimmer as the battery drains. Once the battery voltage is below a certain level then the torch just stops working.

You can talk to the electronics teacher and they should be able to help you with a simple circuit.

Good luck with the project.


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it would be very interesting to see a chart comparing different features of common NiCD, NiMH, li-ion and alkaline, comparing weight to mah and stuff, you know? I know a little bit about batteries, but not much at all, really....

with the different colors, I nkow there are multi color LEDs, not sure how they work though, but I think they make them so out of one LED you can get a few different colors (I might be wrong, i really might). if you could find out about those, then it's possible you could build it with LEDs that switch from white to blue.

and one other thought that is completely ridiculous, make it dmx controllable or something, so you can do RGB mixing on it! You could hook it up to a board, program a color into it, then make it so it retains that color, so you don't have to have it hooked up all the time. That'd be totally pointless, but funny! also, it'd be more circuits and weight.


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It is quite plausable(and intriguing) if using a pocket size console!


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well, what would really i think be best is, like, you hook it up to dmx or maybe use USB if you could and write your own software or whatever, but make it so you can load in the color, you would mix the RGB on the board, then send that info to the flashlight, where it would be stored in a flash type memory, or something like that. then, when you turn it on, you can use a three way switch--off, on(white) or on (whatever RGB you have it set to) or something like that. Then you don't have to carry around a small console :)

however you could build a couple and have a neat little mini show to mess with during down time at the theatre :)


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a DMX controlled flashlight. It would be cool, but way out of prortion to this project. Wouldn't Red be a better color then blue for a selectable light mode?


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I would love it, but its out of my ability / resources for this project. Let's get back to actually building the thing instead of starting the DMX idea list here.


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Here is my first idea. 6 white LEDs and 1 Red LED. Seperate modes, white for strike and set-up, and red for show time


Let me know what you think. Should I try to cram 2 more white LEDs in or another Red one?

Where should I put switches and such? Momentary on the back?


Just picked up two led conversion kits for the mini mag lite from the nite ize store online. Works great. The kit was only $7.50. The mag light is much brighter, cheaper, and easier to carry than some of the bulkier led lights on the market today.

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