How to build my own light?

Hi,

I am looking for a nice mini flashlight, but can not seem to find one that does all that I want.

So, I thought that it would be a fun electronics projects to create one for myself. (I want to learn about electronics... I did once take a basic DC circuits class, but that is all my education thus far.)

I figure maybe I can look in the yellow pages for a local machine shop and ask them to help fabricate the actual casing...

But, where can I find information pertinent to this task?

Specifically:

- What are the best LED's to use? (and why?)
- What kind of control circuits are popular?
- Where can I buy the parts?
- What about the optics?

If anybody can point me in the right direction, it would be a great help. :thanks:

Thanks,
David

welcome, BSD! Oh, boy, you are in for a fun ride!

What do you want your light to do for you? Chances are something similar is already available and you only need to tweak it a little. What is the intended use for this light you want? Do you want it bright, or long running? How big/small? There are so many possibilities that knowing these basic things will help us suggest more specific things.

Maybe you can stop by the Shoppe and check out the available parts. You'll have to read up on the converters on the "Sandwich Shop" section here on CPF. Wayne sells a lot of converters, optics, reflectors, LED's,... you name it! Other sources for electronic parts are Digikey, Mouser (sp?), Fry's and Radio Shack. There are also people on CPF selling parts and electronics, one of the modders with a lathe might even be willing to help you with your design.

I started by modifying existing lights. Much "easier" laughing: yeah, right!) than trying to build my own light from scratch. It made me realize I don't have the skills or tools to do this myself.

Hi greenLED,

Thanks for replying!

Basically, I am looking to create a small "1xAA or 2xAAA sized" LED flashlight.

Priorities are:
- Brightness.
- Maintenance of this brightness for life of the power source. (With "moon mode" at end...)
- Runtime, within reason, is _not_ an issue. ~20 minutes would be all I need it for.
- Preferably able to run from an alkaline or NiMH cell.

I certainly could try to modify an exiting light, but I am really also looking for a chance to learn more about electronics.

You're very welcome.

One of the first mods I attempted (took a larger bite than I could swallow, but I had a blast doing it) was to make a "sammie" (from the Shoppe, a converter+emitter+LuxI) and put it into a minimag. I think I fried one or two boards and destroyed a couple of Luxes before I got it right. That introduced me to soldering small-ish parts and I got to play with optics and reflectors.

Based in that experience, I "short-stacked" a sammie (made it shorter than regular height) and crammed it into an Infinity Ultra head. I used a MadMax converter (MM for short) so it could be powered off a single AA. There's a fair amount of boring, drilling and cursing involved so you may want to try it too. Oh, yeah, I sanded my fingerprints off in the process :green: that hurt for a couple of days... but gave me a great story to share

With one of those new AA-sized Li-on rechargeables, you could probably use a NexGen or a BadBoy converter. I'm not up to speed as to what the combinations are. Look for the mini-minimaglite threads to see what converters people are using when powering them with one li-on AA. That'll also introduce you to the li-on universe.

Also there's a couple of threads where people have actually published dimensions and renderings of the lights they build so you may find those useful.

Ah, I just remembered, look on taskled.com for variable-brightness converters (the maker of the boards is a member here, of course). Icarus makes some killer mods using those.

I'm just a noob modder (and ignorant about electronix) so I'll shut up now and let the real modders step in and give you more suggestions.

Hi,

I am not yet at all familiar with the flashlight enthusiast culture, so some of the names you and terms you are using are unknown to me.

Is there a document out there that explains the theory of operation behind modern high power LED lights? It seems that there are some rather complicated electronics involved. (As I said, as a learning experience, I would prefer build vs. buy... )

Thanks again

BSD said:

Is there a document out there that explains the theory of operation behind modern high power LED lights? It seems that there are some rather complicated electronics involved.

Click to expand...

There's a couple, but I can do it here for you. LEDs are not that complicated.

The high power leds are different from the little 5mm and 3mm ones mostly in that they are big and powerful enough that they need heat sinks. If you don't heat sink them they start to get hot, the heat decreases their resistance, they pull more current, get hotter, and they burn out in a day. Which sucks if you've put the whole morning into mounting a $40 LED to your liking. So you give them heat sinks.

LEDs are current sensitive devices. They all have an acceptable range of current for operation. You stay in this range, they're happy, they'll run for years, decades even. Below their range they won't light or will just barely have a little bit of glow. Above their range they'll run real bright, but not for long.

An example:

Take a cool white one-watt Lumileds Luxeon star. It's a good basic unit. Depending on how hard you run it you can get from 30 to 45 lumens out of one.

It will start to glow around 2.8 volts. At that level you'll be getting around 30 lumens. Push it up to 3.4 volts, which is what the manufacturer suggests. you'll have maybe 37(?) lumens output, a respectable lifespan, the heatsink can handle it, it's pulling a safe 350 mA, (Milliamps) everything is groovy. Take that same unit, run it at 4 volts. You'll get 45 lumens out of it, but it'll be producing a lot of heat, pulling a dangerously high mA. level, and you're not going to get any 100,000 hours runtime out of it. Which one is best? Well, that's your decision.

All of this business with fancy electronics is just ways to make sure that your LEDs are getting enough mA, and never too much, even though the strength of the batteries will change over time.

Another fun kit to build is any of Lambda's kits. The latest of which is the Mini-Pro. It has a nifty heat sink included with it. While the electonics are not as complex as some others, it gets the job done. His kits come with all the nessessary bits exept the lux to modify a mini-mag.

cheers,
zwf

OK, thanks for the help so far.

I think I'll start by building my own test/sample regulation circuit with the kind of LED I would ultimately use in a 1xAA flashlight.

What kind of LED should I get if I want ~20 minute runtime from a 1xAA cell? What are the quality issues involved?

Where can a find schematics for the necessary step-up/regulation circuit? Preferably micro-controller based... I have an Atmel STK500 development board sitting here. (Though, I've never used it, as I said, I am new to electronics... )

Also, what am I trying to "regulate" anyway? Voltage? Current? Both?

Thank you,
David

P.S. Does this perhaps belong on the "Flashlight Electronics" instead? Should I post a message there?

BSD, I too was thinking about posting a thread similar to this one. I'd like to see a basic "idiots guide" to flashlight/LED electronics. IE: what is a milliamp and what does it do? Volts? How do these effect different LEDs?

I like playing around with this stuff, but I really dont know what I'm doing. I can follow directions well, and I've built a Mag85, Mag18 (I think thats the number), and a few others. I'm going to do some minimag modding with some 5mm LEDs I just bough in the group buys, and I want to replace the LEDs in my Princton Tec headlamp with some brighter ones, but I have no idea how that will work, I'm sure it will, but I plan to ask lots of questions and do lots of searching/reading here.

Anyway, some basic theory would help.

Thanks.

This is a great guide and well written .
https://www.candlepowerforums.com/threads/92993&highlight=guide
Takes a while to read it but worth it.

Welcome to CPF.

BSD said:

Also, what am I trying to "regulate" anyway? Voltage? Current? Both?

Click to expand...

Current. LEDs are current sensitive.

Useful resources:
http://home.comcast.net/~theledguy/home.htm
http://home.mchsi.com/~lambda_lights/index.htm
http://theledguy.chainreactionweb.com/index.php

BSD,

Welcome to CPF!

As Greenled said, oh boy, you are definitely in for a real fun ride!

Many good suggestions had been given, and just my extra 2 cents worth--in a humble write up of mine, there is section 2 which details some of my dummy thoughts on luxeon and bin code, different types of regulations, optics, after market vs modding, etc--Dummy Reference guide to Minimag mod

Certainly, not everyone is a minimagaholic like me, but it might bear some relevancy. Parts for all the mods detailed in that post could be found 99% time on CPF and the related resources. And depending on your time, you could find some ready made solution for your light as well.(such as the late MM lite RY0J sandwich from Sandwich Shoppe or Lambda MiniPro or his sammie series)

Anyway, if I were to recommend one thing, then it will be doing good researching on this site--CPF is truly a wealth of information, people are friendly and helpful and great resources ready to indulge any flashaholic's dream comes true.

Best of luck to your endeavor, and come back and share us your story! :thumbsup:

Also, if you want to build the whole thing from scratch, body included, you don't necessarily HAVE to use a cylindrical design.





You can stuff LEDs into any enclosure, provided that you also build some sort of heat removal path into the contraption.

oO

Thanks to all for the above tips and links!

Since I am not yet sure if I want to build a head-mounted or hand held unit, I think I'll start by building a couple of test circuits on a breadboard...

OddOne: Do you have more pics or a description for that cool light?

BSD said:

OddOne: Do you have more pics or a description for that cool light?

Click to expand...

Yes, actually. Did a write-up with a discussion on construction details for my LED site. The light's nicknamed Snake Eyes and the article on it can be found here.

There's also a sequel, Snake Eyes 2. SE2 packs more heatsinking, two 3W Luxeons instead of 1W, and one of georges80's uFlex controller boards for digital operation. The writeup on that monster's here.

oO

welcome BSD... well CPF is def. the place for learning how to make LED lights.. I think you are on the track... building test ckts outside your light is a good idea..

If you want the most bang-for-buck you can build yourself a very simple ckt to have a 'did it myself' and have amazing output from a single AA light..

MrAl designed an 'LDO' ckt for me that i tweaked for my projects and i've used the design in several drivers, it's easy to customize and is pretty 'nuc proof'.. (navy version of foolproof).. http://ldo.rouse.com is the ckt.. it works with a Litiium Ion cell.. and you'd need a charger too... http://charger.rouse.com shows how to build one for just a few bucks... there is a lot of overhead in getting the parts for the charger so if you can't source them cost-effectivly i will typically sell a 'diy kit' that includes all the chips you need for $10... but you can also buy chargers and cells from AW so that's probably the way to go.. maybe for $20 get 2 cells and a charger.

With the LDO driver you only 'drop' voltage.. you start with a single LiON cell that starts at 4.2 but drops to about 3.5V during use... the lux emitter you'd want to run between 3.7 and 3.5V most likely and the 'LDO' ckt drops the difference, keeping the voltage at the emitter fairly constant.

the LDO ckt described in the thread mentioned has about $2 in parts... you will need some serious magnification to do the soldering you'd want to buy spare parts, but even if you bought 3x it's $6, and there is tremendous satisfaction when you build your first one and it lights up!

you can look at http://rouse.com/circuits and http://rouse.com/nano to see my 'dead bug' circutry which you can mimic.

If you start with a host like an AA single twisty style light... the toughest part is building the little circuit board.. i can make 14mm and 10mm diameter bare copper blanks in seconds, you can to with a $15 cutting tool used for making 'plugs' that you'd cover up screw holds when woodworking.. called of course a 'plug cutter' they are available in any size... http://bitsnbores.com/ is where i buy them, but i can include a couple free if you buy the chips to make your LDO from me (i don't really 'sell them' ala dat-2-zip store.. it's just a 'favor for CPF members' thing i do occasionally.

AA alkaline batteries i don't trust for more than 1.5W of power.. AA Nimh you can get 2+ from but an AA LiON has no problem putting out 4W+.. it will get blazin' hot in an AA running that bright.. i would configure it to be like 500-600mA and you'll get 50+ lumen of light.. stunningly bright... if you can find a host that will fit a McR20 or McR18 reflector you will be doing yourself a favor.. and the higher the drive the more you have to worry about heat-sinking.. my driver can be configured for just about any current level i use a potentiometer in the one-off desgins so i can change the level with a dial, but i dropped that for 3-level twisty design with 3 pre-determined resistor-set levels now.

http://nano1.rouse.com i believe is the thread for my AAA version of the light you are attempting to make. (which you will make actually given enough motivation).

Good luck have fun, be prepared with spares of 'tiny' parts and keep asking questions.

-awr