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Thread: Project Lamplighter - my homemade LED keychain fob

  1. #31

    Default Re: Project Lamplighter - my homemade LED keychain fob

    I love the green! I wonder if you can get an aqua/cyan/teal/505nm SMT LED. Our eyes are very sensitive to that wavelength.

    BTW a coat or three of superglue over the hot glue should make for a pretty tough surface.

  2. #32
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    Default Re: Project Lamplighter - my homemade LED keychain fob

    It's kinda/sorta a little bit like a see-thru ZA-4 Firefli ? Those have been tough to find for quite a while.

    Is it on/off ? Or constant on for glow?

    I would be interested in these if you plan to make them available....
    Last edited by archimedes; 11-06-2011 at 01:08 AM.
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  3. #33
    Flashaholic* nein166's Avatar
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    Default Re: Project Lamplighter - my homemade LED keychain fob

    What happens if the battery dies in the night and you need your keys, you won't be able to see where it is.
    You need redundancy! Could you use that tritium keyfob as the plug in the battery end?
    Heating the tubing with a hair dryer should make it pliable enough to drop the batteries in and shove it over the trit fob.

  4. #34
    Flashaholic sunny_nites's Avatar
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    Default Re: Project Lamplighter - my homemade LED keychain fob

    Take a look at two part, 5 minute epoxies for a top coat over the hot melt glue. In thin coats it is clear, (thicker coats would have an amber tint) very hard and does not attract lint. It does tend to trap air bubbles but with some practice and very thin coats you could probably get some good results. There are a bunch of different brands but I usually use loctite.
    So many LEDs, so little time...

  5. #35

    Default Re: Project Lamplighter - my homemade LED keychain fob

    Finished another lamplighter this evening, this time with an orange LED. I'm trying a different treatment on this one as well - instead of using hot glue on the business end, I'm going with a clear epoxy. Even with a hard scratch-proof coating over it, the hot glue cures somewhat opaque over a couple day period, so this should hopefully keep everything nice and clear for a long time.

    First up: a comparison pic of the three I've completed so far!



    And next, a little shot to show you what they look like on my bedside table. I've thrown a couple lights with trits in there for good measure.



    That's it for pictures right now. I'm currently working out a graceful way to remove the batteries. It's possible right now, but it's somewhat... violent.

    More to come!

  6. #36
    Flashaholic* AnAppleSnail's Avatar
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    Default Re: Project Lamplighter - my homemade LED keychain fob

    Quote Originally Posted by calipsoii View Post
    That's it for pictures right now. I'm currently working out a graceful way to remove the batteries. It's possible right now, but it's somewhat... violent.

    More to come!
    This seems like an ideal place for 2 ultracapacitors in series for 5v, and a mini USB socket with a 20 ohm resistor. Plug your keys in once every few weeks and they'll glow forever...

    Call it "NiteLight for Life" and you've got a winner.

    Edit: Further, it turns out that using 2 2.5v ultracapacitors as described gives you about half as many mW-weeks as you had farads of capacitance.
    Last edited by AnAppleSnail; 11-07-2011 at 11:11 PM.
    My biggest light-hog is my camera.

  7. #37
    Flashaholic sunny_nites's Avatar
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    Default Re: Project Lamplighter - my homemade LED keychain fob

    Looking good!
    Last edited by sunny_nites; 11-10-2011 at 07:15 AM.
    So many LEDs, so little time...

  8. #38

    Default Re: Project Lamplighter - my homemade LED keychain fob

    Quote Originally Posted by calipsoii View Post
    I used 100k ohm resistors for both. At first I couldn't even tell if the LED was lit, but it's more than enough light at night.
    With a sense resistor this high, your constant current supply isn't doing much. You'll likely get results that are just as good if you simply drive the LED through the 100k resistor alone and save yourself the space and trouble of building the whole circuit. With a green LED and 4 alkaline cells, you'd get (1.5V*4-3V)/100000ohms = 30uA, which is a theoretical runtime of 42 days with your 30mAh cells (likely longer due to voltage droop). With your constant current supply, it's impossible for the drain to be any higher than that 30uA, so if 42 days is enough, I'd go with just the resistor.

  9. #39
    Flashaholic sunny_nites's Avatar
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    Default Re: Project Lamplighter - my homemade LED keychain fob

    Good point, Everett.

    Since calipsoii got me thinking about low power LED drivers I've been playing around with constant current circuits and resistors as well. In my experiments I found that with the high value of the sense resistor, the traditional 100k bias resistor would not work and you ended up driving the LED with what ever value the sense resistor gives you. But with the right combination of resistors (I used 330k bias and 33k sense resistors), I'm able to run my LED with 20 micro amps from 9 to about 4 volts. Drops under 20 micro amps with less than about 3.6 volts but still bright enough to be useful.

    Changing the voltage across the circuit is an easy way to tell if your circuit is actually working or not. If it is maintaining a constant current, the draw will stay approximately the same at 9, 6 or 4.5 volts. If the current draw changes with the voltage by a proportional degree, the circuit is not really working and you are just using the drop across the sense resistor.

    Using a resistor is vastly simpler but you would get variable brightness as the batteries fade. Although over the time frame for use (with LR44s with 200mah capacity, should run well over a year), not sure if you would really notice it.

    This is the first circuit I've built and etched in about 20 years and the first time I've built one from scratch with surface mount devices and that has really been fun. So, you do get some payback from the satisfaction of getting something that tiny to work the way you want it to.
    So many LEDs, so little time...

  10. #40

    Default Re: Project Lamplighter - my homemade LED keychain fob

    Calipsoli, these look awesome! I'd be in for like five =)

    Interesting thing, is that I have a NiteIze little tiny button cell light intended for zippers. I forget the name. I had it on my First Aid bag on a camping trip and forgot to turn it off. On fresh cells it's pretty bright, but it was dim and I figured the batteries were dead. Well, like 5 weeks later, lo and behold, the First Aid bag was in my truck, at night, and the darn led was still glowing! Very visible in nighttime. I hadn't actually turned it off (has this little turny knob), and I guess it was on the whole time. Amazing.

    So it's neat that a couple days later I stumble across this thread with a similar idea!! =D
    EDC: MilkySpit 1000-lumen Tri-MC-E L5
    In the car:
    MillerMods Quad-Cree 2D Mag At home: Mettee Tri-P7
    Missing somewhere =( :
    MilkySpit MC-E 2-stage UltraFire C1 SS 123 Keychain Light

  11. #41

    Default Re: Project Lamplighter - my homemade LED keychain fob

    I know exactly the ones you're talking about - I spent some time looking for them in town but eventually gave up the search. http://www.niteize.com/products/ziplit

    My only concern with those was that the runtimes weren't listed so I figured they'd be like all the other keychain lights that ran on expensive batteries and died in 7 hours. I didn't realize they'd last as long as yours has. Might be worth getting a couple shipped here off the internet...

    This project hasn't gotten as much love as I'd like to give it, but that's just because I've been pretty busy. With the Christmas break coming I hope to get a couple days to try a few things. In the meantime, this little guy has been working just fine:


    I'm pretty excited that my runtime test is still going on the prototype unit - 45 days and counting!

  12. #42

    Default Re: Project Lamplighter - my homemade LED keychain fob

    Yeah, I'll have to go back to the truck and check it out - it's where I usually keep my first aid bag and I was too lazy to take the ZipLit off =)

    Not sure how much you'd be able to make these for, if they're labor intensive. But I think yours looks cooler =) I had another ZipLit on my backback but the plastic shattered somewhere and it fell off...

    45 days, that's awesome!!
    EDC: MilkySpit 1000-lumen Tri-MC-E L5
    In the car:
    MillerMods Quad-Cree 2D Mag At home: Mettee Tri-P7
    Missing somewhere =( :
    MilkySpit MC-E 2-stage UltraFire C1 SS 123 Keychain Light

  13. #43
    Flashaholic* legtu's Avatar
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    Default Re: Project Lamplighter - my homemade LED keychain fob

    this is very interesting...

    with the assumption that constant brightness isn't an issue, i'm curious if the constant-current circuit is worth enough to outweigh the simplicity of just using a resistor?

    i've been browsing around with regards to simple CC circuits and found this:
    http://electronicdesign.com/article/...rator6268.aspx
    can i use it as an alternative to the one in the instructables link?


  14. #44

    Default Re: Project Lamplighter - my homemade LED keychain fob

    Quote Originally Posted by legtu View Post
    with the assumption that constant brightness isn't an issue, i'm curious if the constant-current circuit is worth enough to outweigh the simplicity of just using a resistor?
    Problem with a single resistor is your light starts out bright and dims over time as battery voltage falls. Me, I think the complexity is worth it to get flat output. Others may disagree.

    http://electronicdesign.com/article/...rator6268.aspx
    can i use it as an alternative to the one in the instructables link?
    There are two kinds of constant current circuits: one kind will regulate the current for changing loads, but only proportionally to input voltage. I believe this would be better termed a current limited circuit. This is useful for many applications with a fixed input voltage and a variable load (such as a device plugged into wall power via a regulated power supply), but that's just the opposite of a battery powered LED -- for that, a simple resistor would produce about the same results.

    The other kind of regulator circuit will maintain output current even if the input voltage changes. This is more useful for battery powered LEDs, because the load doesn't really change much (only a tiny bit with LED temperature) but the input voltage sure does (from ~6.4V to ~4.0V using four button cells).

    I'm no EE, but that single-transistor circuit may not adjust for changes in input voltage. I suspect that's why the Instructables circuit uses a second transistor in a feedback loop, so input voltage doesn't affect output current. Hopefully someone who knows more can confirm or deny...

  15. #45
    Flashaholic* legtu's Avatar
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    Default Re: Project Lamplighter - my homemade LED keychain fob

    i finally was able to make me one of these using the CC circuit and one with just a resistor. i'm just not seeing too much advantage with the CC circuit so i'll be making subsequent key fobs with just resistors. me thinks i wouldn't notice (or mind) the decreasing brightness over the span of months or years.

  16. #46
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    Default Re: Project Lamplighter - my homemade LED keychain fob

    Very cool project. I'd love to do something like this using an AAA Eneloop.

  17. #47

    Default Re: Project Lamplighter - my homemade LED keychain fob

    Quote Originally Posted by calipsoii View Post
    What flashlight is that on your keys?

  18. #48

    Default Re: Project Lamplighter - my homemade LED keychain fob

    Quote Originally Posted by dongdong View Post
    What flashlight is that on your keys?
    That's a Peak Eiger AAA in stainless steel.

  19. #49
    Flashaholic* AnAppleSnail's Avatar
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    Default Re: Project Lamplighter - my homemade LED keychain fob

    Quote Originally Posted by TyJo View Post
    Very cool project. I'd love to do something like this using an AAA Eneloop.
    I've got 2 alkalines and a 5.5 kOhm resistor duct taped to a white LED with the inverted cone optic. I don't trust my multimeter very far, but at ~3mA it's quite usable to walk from room to room. I wonder if it violates the spirit of this project to have a low/high switch? I want to add a ~50kOhm setting. It runs fine on 2 niMH.One other ponderable is: removable cells or built in charge? Likely trickle charge. I can think of interesting ways to manage that safely...
    My biggest light-hog is my camera.

  20. #50
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    Default Re: Project Lamplighter - my homemade LED keychain fob

    Quote Originally Posted by AnAppleSnail View Post
    I've got 2 alkalines and a 5.5 kOhm resistor duct taped to a white LED with the inverted cone optic. I don't trust my multimeter very far, but at ~3mA it's quite usable to walk from room to room. I wonder if it violates the spirit of this project to have a low/high switch? I want to add a ~50kOhm setting. It runs fine on 2 niMH.One other ponderable is: removable cells or built in charge? Likely trickle charge. I can think of interesting ways to manage that safely...
    The only "issue" that I see with using one or more AAA's is that it'll be a bit large for a keyfob.

  21. #51
    Flashaholic* AnAppleSnail's Avatar
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    Default Re: Project Lamplighter - my homemade LED keychain fob

    Quote Originally Posted by potpot View Post
    The only "issue" that I see with using one or more AAA's is that it'll be a bit large for a keyfob.
    Rather than continue taking this thread on really neat, ultra-small, ultra-low-output lights, here's a link to my build:

    Midnight Light

    Calipsolii, this is a really neat project. How did you attach the split ring to your light?
    My biggest light-hog is my camera.

  22. #52

    Default Re: Project Lamplighter - my homemade LED keychain fob

    AnAppleSnail has done a really nice job with his build, you guys should check it out! I wish I could say I've recently spent time on this project, but lately I've just been busy on other things.

    The original runtime test is still ticking along though. Hard to believe I plugged this thing in almost a month before Halloween!


    I'm pretty happy with my new method of sealing the business end. This little guy has been on my keychain taking hard wear for over a month and still looks pretty good. Just need to perfect the anti-scratch and we'll be set.


    I have a good idea in my head of what I want the final product to look like, so now I just need to time to sit down and get it done. More updates to come...

    Cheers!

  23. #53

    Default Re: Project Lamplighter - my homemade LED keychain fob

    This thread is quiet.

    Too quiet.



    I only just stumbled across this thread and this thread (I don't know how, they're half a month old now). If you haven't checked them out, you should! sunny_nites has posted a build log for a couple different designs of his Beacon Light. The potted epoxy ones look great, imo.

    In his first paragraph he mentions sales. Despite all the silence in this thread, I've been working excitedly on my Lamplighters in my spare time. Of all the little projects I've been tinkering with over the last while, I'm really passionate about this one. I've been carrying all manner of different designs around on my keychain for weeks now, tweaking and testing little things. I think I'm finally ready to take the plunge into the last thing I've never dabbled in - machining.

    Not personally, mind you, but at a local shop. After explaining the idea to the resident machinist, who took a while to get over the idea of a bunch of people collecting flashlights ("There really is a website for everything, isn't there?") he happily agreed to help out.

    If you've followed any of my threads, you'll know I LOVE to post pictures and updates, so it's killing me sitting on the design docs and not being able to post them. That said, if I posted the schematic and then found a cheap knockoff on DX or KD a month from now, it'd totally rain on my parade. I really don't mind if people like the idea and design their own version (I've enjoyed reading the build logs that some fellow CPF'ers have posted) but an exact replica of this final design would suck all the fun out of this hobby for me. As anyone who's ever modded anything can attest, there's a very visceral satisfaction to be gained from turning a nebulous idea into something physical that you can hold in your hands. I suspect by the time I see this through, most of the fun will have been making it happen and the final product will just be the icing on the cake.

    So there you have it, my justification for being such a scrooge with the pictures.

    That aside, here's where I'm at right now:

    Design (host): 100%
    Design (PCB): 15%
    Components (sourcing): 30%
    Prototype (body): 0%
    Prototype (internals): 5%

    I know a lot of people commented that at such high sense resistor values, it's incredibly likely that my constant-current circuit is doing nothing and the resistor is doing all the work. I believe you, but I'm keeping all the components of the design in regardless. What can I say, I'm stubborn.

    So what does this giant wall of text mean?

    Well, in short, it means I'm making a really cool Lamplighter. It'll run on 4x LR41/SR41's. It'll be visible from as many angles as I can manage. It's going to be partially made of stainless steel or brass or copper or titanium (or whatever looks the coolest). I'm having it CNC'd, which means this is going to cost a fortune - I hope it's worth it. Once it's made and I post all about it here, if you think it's worth it, I'll make you one too.

    Cheers!

    - Mike

  24. #54
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    Default Re: Project Lamplighter - my homemade LED keychain fob

    So this is the beastie you had a picture of in the A2 thread. Very nice little light. Waiting to see what you come up with when you get a machined version.

    Does delrin come in clear? That would be really cool, a machined clear plastic light.

    Cheers,
    Nova

  25. #55

    Default Re: Project Lamplighter - my homemade LED keychain fob

    Quote Originally Posted by ^^Nova^^ View Post
    Does delrin come in clear? That would be really cool, a machined clear plastic light.
    I've seen only "natural" (yellowish) and black delrin, but acrylic and polycarbonate come in clear and can be machined. Difficult to get a smooth surface finish on, but you can flame polish the result for gloss.

  26. #56
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    Default Re: Project Lamplighter - my homemade LED keychain fob

    Quote Originally Posted by calipsoii View Post
    This thread is quiet.

    Too quiet.
    Well, I for one am just waiting to see the next major development - unfortunately I don't have anything useful to add so I generally keep quiet....
    Looking forwards to it!

    PS After a couple of days use, the A2 ring is just PERFECT for my needs!

  27. #57

    Default Re: Project Lamplighter - my homemade LED keychain fob

    wow, this is amazing, have you considered any other technology other than led for example EL wire which glows more naturally has very high efficiency but requires complex circuit to drive

  28. #58

    Default Re: Project Lamplighter - my homemade LED keychain fob

    Just a quick little update on this project...

    First, the runtime test continues! This little guy has been running 24 hours a day on four tiny LR41 batteries since a month before Halloween.


    Second, I'm just putting the finishing touches on my CAD, then it's onwards to the PCB. Need to get the PCB design into Eagle and send it to the fab house. I'm hoping they'll be able to work with the small dimensions. I ordered a lot of the other parts so I expect to be assembling the components by the end of the month. Then the CAD goes to the shop and they make me a host for all the guts.

    Hopefully.


  29. #59

    Default Re: Project Lamplighter - my homemade LED keychain fob

    Quote Originally Posted by calipsoii View Post

    And next, a little shot to show you what they look like on my bedside table. I've thrown a couple lights with trits in there for good measure.
    Ok, I'll bite on the unrelated A2 tritium mod: how did you mount a what size tritium vial in the pocket clip of your A2 in front of the clock?

  30. #60

    Default Re: Project Lamplighter - my homemade LED keychain fob

    Quote Originally Posted by btorrenga View Post
    Ok, I'll bite on the unrelated A2 tritium mod: how did you mount a what size tritium vial in the pocket clip of your A2 in front of the clock?
    It's a 2x8mm white trit that I installed with Norland 61 optical adhesive.

    The installation basically went like this:
    1. Remove the clip from the light
    2. Lay waxed paper across a wad of PlayDoh and press the clip down into it, moulding the paper/dough up around the sides to seal up all the holes
    3. The 2 raised pieces of metal at the end of the clip are 1.95mm apart, so the trit won't fit between them. I snapped one off, laid the trit in place, then placed the other piece of metal beside it.
    4. Carefully fill the area with Norland
    5. Hit it with some UV to set it in place, then remove the PlayDoh/paper from around the trit and clean up any mess with a towel.
    6. Apply a bit more Norland, then more UV light
    7. Once it looks good and you've cleaned up any wet Norland, set the UV up for final cure

    The result looks pretty good all things considered (you can barely see that the right piece of metal was broken and reattached):



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