Project Lamplighter - my homemade LED keychain fob

[calipsoii]

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!

 

[mcmc]

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!!

 

[legtu]

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/components/single-transistor-constant-current-generator6268.aspx
can i use it as an alternative to the one in the instructables link?

 

[tylernt]

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/components/single-transistor-constant-current-generator6268.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...

 

[legtu]

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.

 

[TyJo]

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

 

[dongdong]

What flashlight is that on your keys?

 

[calipsoii]

What flashlight is that on your keys?

That's a Peak Eiger AAA in stainless steel.

 

[AnAppleSnail]

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...

 

[potpot]

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.

 

[AnAppleSnail]

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?

 

[calipsoii]

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

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!

 

[calipsoii]

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

 

[^^Nova^^]

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

 

[tylernt]

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.

 

[mat_the_cat]

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!

 

[bobbagum]

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

 

[calipsoii]

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.

 

[btorrenga]

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?

 

[calipsoii]

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):