# Credit card sized light, 1.6mm thick



## balou (Jan 7, 2009)

hi,
this design was floating around my head, and then I just had to draw a preliminary sketch in eaglecad. basically it's an ultra-thin (1.6mm, 0.06in) credit-card sized, wallet-conformant flashlight with a very wide beam and an output of guesstimated 24'000mcd 

specs:
powered by 4x cr2016 lithium coin cells, two in series. powering 4 samsung 3-chip smd leds.

the base for the whole thing is a 1.6mm pcb, with holes drilled for the coin cells and the leds. contact to the coin cells can be made with a small strip of aluminium or copper foil. as a substitute for top and bottom plates I thought about using pda screen protector foils. they are tough and just a tenth of a mm or so thick. some sort of print-on stickers could also be used, to make a business card with an integrated flashlight.
the switch is a momentary SMD switch by omron which is just 1.3mm thick. btw, the switch is the little thingy on the right. it's sunk in a bit, to make accidental activation in the wallet a bit harder

here's a pic of the led mounting method:






and here's the rough pcb layout:





LEDs: http://www.led-tech.de/de/Leuchtdioden/SMD-LEDs/Samsung-Ultrabright-SMD-3-Chip-LT-1323_1_2.html
SMD switch: http://uk.farnell.com/omron-electro...p/tactile-switch-side-actuated-smd/dp/1333655



so... any comments whatsoever welcome. is there already such a light? (I know there are some which contain a 5mm led and lr44 batteries. obviously they're not really 'credit-card sized'). do you think that such a thin light is a stupid idea?


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## spencer (Jan 7, 2009)

I like the idea of this really thin light. It is similar to another project but much thinner. I like it because you could have one in your wallet. I recommend continuing with this project. Not a stupid idea.


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## hamheart (Jan 7, 2009)

good idea but there is another light similar to this called the chimera mini so you might want to check it out.


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## balou (Jan 7, 2009)

yeah, but the chimera is 5 times as thick 
will probably not fit into a wallet anymore

by the way, I just saw that the circles are only 16mm in diameter, they should be 20mm. will correct that tomorrow.

I also thought about a smaller version, maybe 24x32mm, with just a single led and single battery. or a half-credit card sized version with the 4/4 configuration. smaller size would mean that it's less prone to break if you sit on it while its in your wallet, and also lower pcb manufacturing costs (a 100x80mm prototype board costs about 60$ with all tooling fees and shipping included )


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## clg0159 (Jan 8, 2009)

Definately a cool design! Have you calculated a runtime on it? FWIW, I generally do not like coin cells b/c they are so expensive.


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## balou (Jan 8, 2009)

runtime will be max 1.5h on idealized energizer 2016 batteries, a more conservative guesstimate would be 1h with real-world battery behaviour and offbrand batteries.

by the way, 20x 2016 coincells are only $3.88 shipped at dealextreme.

energy dissipation of the whole thing would be about 0.75W

but I'd really have to run tests to confirm this... the samsung led datasheet is quite vague about brightness and max power consumption (e.g. they state brightness at 60mA, but half a page above they say that max allowable current is 30mA)


another point: what about chaining all 4 leds and 4 batteries in series to even out Vf differences? anybody got experience with that?


edit:
to put it into perspective with the chimera:
chimera: ~$350, charging circuits, cree led, I guess >100 lumen output
cclight: $20 max, single-use cr2016 batteries, not the most efficient leds, no idea about output, 10 lumen would be great already


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## spencer (Jan 8, 2009)

It says on that site with the LED's that they are 13.5 lumen each so x 4 is 54 lumen. It ends up being 75 lumen a watt so thats not really bad efficiency.


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## Mosser (Jan 8, 2009)

you can already buy a 2mm thick credit card sized torch powered by 2 x cr2016 batteries here in the UK, i was given on for christmas 3 years ago, it was pretty expensive at about £20, but is suprisingly bright and always there when you need it

I think it was made by sinclair, i can do a bit more digging for info if your interested


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## LouRoy (Jan 8, 2009)

This link may interest you:

http://flashlightnews.org/story1071.shtml

Also do a search for Eon flashlight. It is another with a similar idea.


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## balou (Jan 8, 2009)

spencer: kinda overlooked that.... ~50 lumen would be quite bright for such a tiny light

Mosser: do you meat that one: http://www.iainsinclair.com/products/eonclassicintro.html ?
It seems to be 2 or 2.5mm thick at the thinnest point... it's more like 7mm at the thickest point (I guess they use a 5mm led, which has a 5.8mm diam max. then you still need two plastic shells)


One problem that still exists is the switch... I don't know if Farnell even ships to individuals. And the switch is extremely tiny, and momentarily only.

A pressure switch like the sinclair and many cheapo pocket flashlights use is also not an option. Guess what would happen if this light sits in my wallet in my back pocket...

Anybody got an idea for the switch? A switch where you close the contact with your finger would be an idea. But that would need an smd transistor - fingers have to high a resistance to power 4 high power smd leds



edit: I'm curious... would any of you really put a chimera/sinclair eon/other 'credit-card sized' light in your wallet? that would be the size of a stack of about 10 credit cards, whereas 1.6mm is about the size of two credit cards


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## Sabrewolf (Jan 8, 2009)

I have got one in the works that is about 4mm thick.
It will use 2x 200mA li-ion rechargable batts with a 
built-in usb charging jack, 2x Nichie GS leds and will
be made of brass or aluminum. But the price would
be about 100 bucks 

I do like your 1.6mm light idea though 

I really like the walletable idea !!


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## Sabrewolf (Jan 8, 2009)

balou said:


> runtime will be max 1.5h on idealized energizer 2016 batteries, a more conservative guesstimate would be 1h with real-world battery behaviour and offbrand batteries.
> 
> by the way, 20x 2016 coincells are only $3.88 shipped at dealextreme.
> 
> ...


 
I fixed it


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## Sabrewolf (Jan 8, 2009)

balou said:


> spencer: kinda overlooked that.... ~50 lumen would be quite bright for such a tiny light
> 
> Mosser: do you meat that one: http://www.iainsinclair.com/products/eonclassicintro.html ?
> It seems to be 2 or 2.5mm thick at the thinnest point... it's more like 7mm at the thickest point (I guess they use a 5mm led, which has a 5.8mm diam max. then you still need two plastic shells)
> ...


 
You could use a simple mosfet circuit. Then you still keep your momentary switch to turn it on/off :twothumbs


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## balou (Jan 8, 2009)

LouRoy: overlooked your post... I once had exactly such a light. 5mm LED, 3x LR44 batteries, about 6-7mm thick. Way to fat.... and it started to fail after just a few uses.

Sabrewolf: 100 < 300-400 lumens. Nothing wrong about my post 
Oh, and do you know a place where to get sub-2mm lipoly batteries? 
About the MOSFET circuit: only thing that comes to my mind would be a flipflop, and building one in CMOS yourself would probably take more space than available. Or do you mean flipflop plus mosfet transistor?

Such a circuit would solve the momentarily-on problem.. but a bigger problem would in my opinion be the finicky smd switch. Hard to get, easy to break off.

So... an alternative would be a pattern on the circuit board like this:
http://www.maxtechcircuit.com/files/Products/RubberMembrane/Rubber-CarbonTactileKey2.jpg
You close the contact with your finger, and then it either actuates a MOSFET directly, or is preamplified with a BJT (but MOSFETs should probably need a rather small current, so hopefully a BJT is not needed). Because, IF I gonna include semiconductors in the whole thing, I could as well use some more to replace moving parts.

Edit: but SMD parts would again mean that I have to order from an electronics supplier. Farnell seems to be my best choice - shipping costs from digikey to switzerland are 60$


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## spc (Jan 8, 2009)

didn't polaroid make a thin disposable led light a while ago?


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## Sabrewolf (Jan 8, 2009)

spc said:


> didn't polaroid make a thin disposable led light a while ago?


 
Yes, it used the battery that was builtin to the Instant-film cartidges.
After you used the cartidge in the camera, you just shoved it in the 
flat light of thiers and used the battery up.


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## LouRoy (Jan 8, 2009)

balou said:


> do you think that such a thin light is a stupid idea?



No, I think it is a great idea. The ultimate EDC. When can I send paypal??? :thumbsup:


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## snarfer (Jan 9, 2009)

> Farnell seems to be my best choice - shipping costs from digikey to switzerland are 60$


I have this same problem with shipping costs from Digikey, in my case to Thailand. 

I spoke to a representative there a while back and he told me that on request they could ship via the US postal service. Much cheaper. 

I never tried it because I found an even cheaper way - having a friend receive the order in the US and repackage it, which also saves me on customs fees.

Oh almost forgot. Mouser has much lower international shipping fees. So that could also be an option. Farnell tends to have really inflated prices for some reason.


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## balou (Jan 9, 2009)

Sabrewolf: What MOSFET circuit did you mean exactly?

snarfer: Yes, already did that once with letting somebody else buy the stuff and send it to me. Was over at headfi... a bunch of opamps  Will definitely try to piggyback on some other order if possible.


General question: What light output?
50 lumen seems to be a big bright. Especially if you consider the small batteries. I mean, the Fenix E01 has just 10 Lumen. This light would compete with the Photon, Fauxton and the smallest keychain lights, up to maybe the Fenix E01.

Crazy high output or reasonable battery runtime?
A compromise would be 2 LEDs.


Btw, there's space for 6 CR2016 on a credit card. That would be 3v, 540mAh, about the same power as one AAA battery. So if the E01 with all the regulation loss can put out 10 lumen 10h longs... then 20-25 lumen 5h would be not bad.


edit: seems I just contradicted myself somehow . Yes, the light's small, but 6x 2016 provide quite a bit of power, only realised that when writing the last sentence. here's the layout as of now. anybody got a suggestion if I should drive the 2 leds with 2x3 or 3x3 volt? 3v per led might be a bit to dim. BUt - under which condition does this led emit 13.5 lumen as stated on the link above?


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## spencer (Jan 9, 2009)

I would say that each LED emits 13.5 lumen when each die is driven at 20mA. There are three dies per LED and all are individually addressable kinda like the MC-E.


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## DaveNagy (Jan 13, 2009)

I think this sounds like a really interesting idea. Put me down for two! 

Some random thoughts:

No optics, so we're talking a total flood "beam", right? In that sort of configuration, I'd say, "The more lumens, the better." (Within reason.) My Zebralight has a 120 degree beam, and running flat out, it does 70 lumens or so on high. That's a pleasing and ample amount of light for working on a car, or cooking a meal, but it's certainly not "excessive" seeming. (It _would_ be excessive for something like map reading.) My Zebralight does about 12 lumens on medium, and frankly, that seems barely adequate for doing things at arm's length. 20 lumens might be better. (Basically, I'm trying to say that you shouldn't try to compare a focused beam to a an unfocused one of the same "strength".)

Some of the switch ideas be bandied about in this thread sound waaaaay too clever for their own good. Just put a plain old fashioned mechanical switch on the thing and call it done. Something tiny that you could operate with a fingernail would be fine. Seems like you'd want to put it on the edge of the card somewhere, so it could stick out a bit and yet not add any thickness. (Notch the edge of the card where the switch is if you don't the switch to extend beyond the "footprint" of a normal credit card.) Some sort of thumbwheel would be neat and would fit well with the circular theme you've got going. Ooo, and you could possibly do some sort of variable brightness that way!

(I'm talking about the sort of switch like old transistor radios had. You could adjust the volume continuously, but they also "clicked" off when rotated all the way "down". The rotating part of the switch was probably about the size of a US nickle, but only a tiny fraction of it stuck out of the case. You know, kinda like an inline lamp-cord switch?)

I have no idea whether such a switch exists in a sufficiently thin form-factor, regrettably.


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## balou (Jan 14, 2009)

hi Dave,
Yes, beam is also about 120°. Only optics possible would be a 0.5mm thick fresnel lens, or some star-trek-technobabble-sounding stuff.
I think 2 or 4 LEDs, selectable, would be the best bet, that would give light in the order of 20-60 Lumens

Switch ideas too clever: Well, problem is, find me a SMD switch which has 3 positions, and is _not_ of the momentary type 
Even finding a normal on/off SMD switch which is not momentary seems to be a problem.

For switch position: see the pic above, the notch on the right side is where the switch sits. The exact form and deepness of the notch has of course to be tuned, possibly with a cardboard mockup.

The switch thing you're talking about is a potentiometer with integrated on/off switch. One source of them could be old CDROM drives, the ones that still had a headphone out in front. But they're at least 2mm thick, and then you'd still have to mount them somewhere on the card. And they also don't include an on/off switch. Dollar store radios could be another source.

You could probably ask Bourns or Alps to make something like that, but they'll probably don't make custom potentiometers unless you order 10k pieces 

So unfortunately, the switch is a major problems. There are plenty of options, just not in this size... so maybe in the end, this project is going to include a microprocessor, just for switch and brightness handling.

If you want to search for such a switch... try mouser.com, farnell.com and digikey.com

Edit: I forgot: 3 Coin cells in series are necessary - with just two in series, they would have very bad runtime, if you take into account that the coin cells have only two volts if nearly discharged. And two volts don't light up an LED anymore.


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## NonSenCe (Mar 30, 2009)

any news or updates of these?

i dont mind if its even thicker


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## Zeruel (Mar 30, 2009)

NonSenCe said:


> any news or updates of these?
> 
> i dont mind if its even thicker



I guess this will be one of those you're going to lose your fight to.


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## bshanahan14rulz (Mar 31, 2009)

need ideas?

have a few spots marked on the card and include a small Nd magnet to activate reed switches. perhaps card will be made of metal, this way you don't have to hold magnets in place. downside: yay, more small parts to lose!

photoresistor to make card come on when it's not in a wallet?

educate ants and tell them to make the connections inside the card.:thinking:


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## Benson (Apr 1, 2009)

You consider going rechargeable?


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## Zeruel (Apr 1, 2009)

LouRoy said:


> This link may interest you:
> 
> http://flashlightnews.org/story1071.shtml
> 
> Also do a search for Eon flashlight. It is another with a similar idea.



Eon looks very cool. But if this new card light is going to output 20 - 60 lumens, it will probably beat Eon to a pulp.


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## NonSenCe (Apr 9, 2009)

"zeruel: I guess this will be one of those you're going to lose your fight to." 

aH, yEs, I would gladly! -to those who dont know what this means.. i am "fighting" against my flashholism, the basic need and want to get every bright cool thing i see  

in my wallet i normally keep 4 creditcards in each slot.. well i only have 4 cards on me normally  so they all are in one slot.

so i dont mind if it would end up even 6mm thick. 2-3modes would be nice. or dimmable option. (the scroll button is nice idea)
5-10lm low, and 40-100 high. if only one mode, i think i could simply be just a momentary mode with soft press button.

hope there is some advance in this project. 

cheaper chimera mini is always welcome!


one dream of mine: cellphone (sized) flashlight, original lion battery and charging jack, warm tint, etc. if i only knew how to do it i would build it myself.. i would just get a broken nokia and gut it  

or those clamshell phones.. flip it open and it turns on.. or zippo lighter flashlight..or.. (im getting sidetracked again.. sorry)


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## bshanahan14rulz (Apr 9, 2009)

how about instead of putting all the parts on a credit-card sized carrier, you build it and pot it in a credit-card sized mold?


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## balou (Dec 10, 2009)

Just a quick note:
This project just got resurrected.

-Found a local supplier for two-side copper-clad PCBs
-Choose a new LED. Samsung Sunnix 5, warm white LED, 70 Lumens max
-Found supplier of said LED (Led1.de). It's even without s&h 
-URL: http://www.led1.de/shop/product_inf...h511n0-wo-lens-p-1150&cName=samsung-led-c-227
-this LED will require some dremeling to reduce its height
-dumped my idea of etching the boards. Will directly etch traces with a dremel
-holes also to be made with a Dremel
-speaking about Dremel... I'm hoping one of my family members took the hint that I really want a Dremel for Christmas 

*SWITCH PROBLEM STILL UNSOLVED!*

Q&A:


> how about instead of putting all the parts on a credit-card sized carrier, you build it and pot it in a credit-card sized mold?


PCB's are basically just fibreglass mats potted with epoxy. without the fibreglass part, the thing would break in a matter of seconds in a normal wallet...



> so i dont mind if it would end up even 6mm thick. 2-3modes would be nice. or dimmable option. (the scroll button is nice idea)
> 5-10lm low, and 40-100 high. if only one mode, i think i could simply be just a momentary mode with soft press button.


Maximum thickness will be 2mm. My wallet does not hold such thick cards as yours 
Multimode will be quite hard to implement on such a light



> You consider going rechargeable?


To much hassle reloading the whole thing, costs to much, plus would negatively affect the stability of the whole thing (I can space out the CR2016 so that there is enough pcb material to make this stiff enough)



> need ideas?


YES!


> have a few spots marked on the card and include a small Nd magnet to activate reed switches. perhaps card will be made of metal, this way you don't have to hold magnets in place. downside: yay, more small parts to lose!
> 
> photoresistor to make card come on when it's not in a wallet?


Reed switches plus flipflop would take up to much space, photoresistor too



So... two things:
1. I really need a Dremel
2. I really need an idea for the switch

My current idea involves strips of aluminium foil as switches... which will probably be as flimsy and unreliable as it sounds...

edit: another switch idea:
http://www.dealextreme.com/details.dx/sku.16510
Ordered a pack of them, maybe I could gut it and frankentransplant it into my light.
Seems to have a membrane switch though... maybe I could yank it off and have the light activated by any conducting object (key...). But dunno if it could resist the kind of voltages I'm going to use


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## Dave 88 (Dec 11, 2009)

What about a small slider switch like the lockouts on an SD card? 

Just read through this quick, its a neat idea and throwing in my $0.02


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## Sabrewolf (Dec 11, 2009)

Dave 88 said:


> What about a small slider switch like the lockouts on an SD card?
> 
> Just read through this quick, its a neat idea and throwing in my $0.02


 
Sorry to say, But the lockout switch on an SD card
is just a plastic piece. Its actually the SD cardslot
that has the pin switch/contacts


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## balou (Dec 11, 2009)

Samsung LEDs are ordered. One cool white, one neutral white (neutral white fans, rejoice!). They should arrive in a few days.

After reading about it, I decided that I want a Proxxon, not a Dremel. A trip to the hardware store reinforced that sentiment. Proxxon FSB 240/E and the electronics tool set it shall be for Christmas (or well, before Christmas).

Ordered two of those switches: http://www.dealextreme.com/details.dx/sku.15610
They are momentary only, though. Estd arrival date: god only knows...
I'll try to set something up so that you could more permanently activate the light with some alu or copper foil and tape. Still far from perfect... but better than nothing.



balou said:


> 3 Coin cells in series are necessary - with just two in series, they would have very bad runtime, if you take into account that the coin cells have only two volts if nearly discharged. And two volts don't light up an LED anymore.


I seriously have no idea what I babbled here. 2x3=6v should be enough, and it'll be still 2x2=4v at the end of battery life.
CR2016 have serious internal resistance though. 20 Ohm per cell.. that makes already 40 Ohm with two cell in series.

If my math is correct, that would make (assuming Vf of 3.5V):
(6-3.5)V / 40 R = 62mA.
Way underdriven...
A 2s3p cell config would divide the resistance by 3, giving three times the drive current, i.e. 187mA.
By having a quick look at the (confusing) datasheet, that would be in the ballpark of 30 lumens of pure flood.


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## savumaki (Dec 11, 2009)

Definitely not a stupid idea; sounds like a great back up to me. Perhaps not so much for a guys wallet with all the bending involved but it would be a natural for a purse or a shirt pocket.
Also it need not be a super power house for light emission since it would be used for emergency use (in my opinion) and the key feature should be a long run time.
Switch- for the use I just mentioned a 'momentary on' would be more than adequate.
Using the KISS principal will keep the o/a cost down and make it affordable; after all you're not expecting it to start breakfast are you?

save me some

Karl


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## Hallmcc (Dec 11, 2009)

balou said:


> One problem that still exists is the switch... I don't know if Farnell even ships to individuals.


 
Is using two copper strips laminated to opposite sides of the card stock and a hole in the card out of the question? squeeze to turn on, release to turn off.


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## balou (Dec 11, 2009)

Hallmcc said:


> Is using two copper strips laminated to opposite sides of the card stock and a hole in the card out of the question? squeeze to turn on, release to turn off.


I'd have to test if that'll be no-accidental-activation proof.
Anybody got an idea where to get copper tape? (except eBay... more like which kind of B&M store)



> Perhaps not so much for a guys wallet with all the bending involved but it would be a natural for a purse or a shirt pocket.


The plan is that it'll be tough enough to withstand the abuse of daily backpocket wallet carry. FR4 PCBs are quite tough and at the same time flexible. Biggest point of failure is probably the solder joint of the LED. 

Maybe I have to reduce from 6 to 4 batteries - more room for the switch, and for thicker segments of PCB between the batteries.

I also thought about renaming the project to business card light. Mainly because such a thing would make an impressive business card.


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## savumaki (Dec 11, 2009)

[QUOTE
I also thought about renaming the project to business card light. Mainly because such a thing would make an impressive business card.[/QUOTE]
If I was still in my past profession I would not hesitate to order several doz. for my 'special' customers; GREAT THOUGHT.


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## Hallmcc (Dec 11, 2009)

balou said:


> Anybody got an idea where to get copper tape?


 
How about using something like this.
http://www.dealextreme.com/details.dx/sku.5170

easy to find and cheap got an old computer? :twothumbs


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## Sabrewolf (Dec 12, 2009)

Hallmcc said:


> How about using something like this.
> http://www.dealextreme.com/details.dx/sku.5170
> 
> easy to find and cheap got an old computer? :twothumbs


 
I dont think there is any copper foil in those


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## balou (Dec 12, 2009)

I'm having a hard time deciding if I should get up and grab a Proxxon right now...
On the one hand, I still somehow wish somebody will get it for me as a Chrismas present.
On the other hand... let's face it... no  The only nice gifts I'll receive this year will be from the CPF Christmas giveaway.

So... -$120 on my bank account this afternoon?
And then grabbing a $8 PCB in eurocard format.
And then waiting for my $30 order of LEDs.
My poor wallet... I hope I can reimburse that by selling some of them at an exorbitantly high price :nana:


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## Dave 88 (Dec 12, 2009)

> Sorry to say, But the lockout switch on an SD card
> is just a plastic piece. Its actually the SD cardslot
> that has the pin switch/contacts



Yes I know, but modify that idea so it has contacts inside a switch like that to fit in this small form factor. If its a squeeze type switch then it kills the idea of being the size of a CC because inside a wallet/etc it would always get turned on. That's what I was trying to suggest.


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## balou (Dec 15, 2009)

So.... finally got to buy a Proxxon drill,
and LEDs arrived today too.

I built a first testbed variant, just one CR2016 and a sanded down 5mm China LED (no more raw fingers from manual sanding. Yay!).

I *definitely* need a better milling bit. The one I have (2.5mm ball) is a real PITA if you have to cut out a 20mm diam hole in a PCB.

The aluminium-strip switch works very badly, if at all.

Hallmcc, your idea seems to be possible. I made a first prototype. The hole is too small to press comfortably, but widening it shouldn't be a problem.
Only problem I see is that the electrical tape will loose tension over time, leading to accidental activation.

I made some pics, but my flatmate took my cardreader, and she hasn't brought it back yet.


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## garilla (Dec 15, 2009)

Just don't sit on your wallet and it should be ok


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## balou (Dec 15, 2009)

garilla said:


> Just don't sit on your wallet and it should be ok



It's meant to be kept in your wallet all the time, and I personally sit on my wallet. So able to sit on it without activation is a design requirement I'd hate to toss away.

edit: flatmate just walked through the door. pics will follow soon


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## balou (Dec 15, 2009)

PCB - 20mm hole cut out, the sanded down DX led, and the line in the PCB I cut with the 0.5mm milling bit. The solder blob looks enormous here - in reality it's just few tenths of a mm. It's sanded down too... must be the sanding pattern...





My work area, and the Clight prototype with first prototype 'switch' visible. Can be activated by some aluminium foil...
That's a vacuum visible - don't wanna inhale to much epoxy dust. I'm also wearing ear plugs and mask. Don't have any safety glasses, just my normal glasses. Might be an idea, a cutting wheel more or less exploded, and strands from the brass wheel brush hit me just above my eye...





You can (barely) see the mould from my squeeze switch prototype.





What would this thread be without beamshots? 
5mm LEDs, sanded down to 1.6mm look ugly...

Just to make it clear once again - the final light still will be full credit card size, and with a Samsung Sunnix5 LED. This was just a prototype to


Get used to my Proxxon drill
Test out different switch ideas

edit:
here's a comparison shot between a Samsung Sunnix 5 and a Cree XR-E (mounted on a MPCB):


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## Sabrewolf (Dec 15, 2009)

Progress! Now we are talkin


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## balou (Dec 15, 2009)

Found out that aluminium foil and electrical tape is _totally unreliable_.

The switch problems I had were possibly caused by the unreliable battery connection and not the switch itself.... I'm switching to copper tape. I'm now gonna order some on eBay. Problem is, what to do in the meantime? Have to look locally... seems copper tape is also used for electrical guitar pickups (edit: not pickups.. pickguards)... maybe snag some at a local music shop

edit: Anybody knows where to get adhesive tape/foil with at least 54mm width? I've seen large transparent adhesive foil before... but I can't remember where. White would be even better though.

edit2: I'm $18 poorer now. Copper tape should be here in max. 9 days. Man, this project is more expensive than I thought... I've spent close to $200 already. Granted, I wanted that Proxxon drill anyway, but still

edit3: locally, copper tape is two times as much... so I guess it could be worse...


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## Hallmcc (Dec 15, 2009)

For the purpose I think that is a great pattern.

I sure enjoy watching the progress as ideas go from a thought, to a prototype, and then final design. 

I know it is frustrating and expensive when failures happen, but darn it, without trying what is really gained? 

As far as the tape switch goes, let me ask you this. Obviously stretch is the cause of the failure. As the tape is pressed towards each other it is stretched over the edges of the finger hole creating micro fractures.

Would tapering the edges and attaching the tape to battery shrink wrap provide the reliability you seek?

The Shrink wrap would act like a return spring when the pressure was released.


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## balou (Dec 16, 2009)

Hallmcc said:


> For the purpose I think that is a great pattern.
> 
> I sure enjoy watching the progress as ideas go from a thought, to a prototype, and then final design.
> 
> I know it is frustrating and expensive when failures happen, but darn it, without trying what is really gained?


Yes, the process itself is interesting.. but the whole thing being cheaper or me being able to order express when I really need the stuff to move along would be nice 


> As far as the tape switch goes, let me ask you this. Obviously stretch is the cause of the failure. As the tape is pressed towards each other it is stretched over the edges of the finger hole creating micro fractures.
> 
> Would tapering the edges and attaching the tape to battery shrink wrap provide the reliability you seek?
> 
> The Shrink wrap would act like a return spring when the pressure was released.


I made a drawing how my switch currently works. Probably easier to show a picture than to explain everything. If you compress the switch, the aluminium foil on the bottom makes contact with the two aluminium foil strips on the top, thus closing the circuit. At the moment, top is strictly V+ and bottom strictly V-. I'll change that with the Sunnix version - one contact less to make, and plus and minus will be on the same side anyway. And as said, the alu/tape sandwich will be replaced by copper tape.





Hallmcc, is that how you meant it, a bit of heat shrink tube as spring?
Tapered edges not yet drawn, and not yet milled.

Btw, the current prototype has, instead of aluminium foil at the bottom, a 5x5x1mm NdFeB magnet. This way, the 'switch' has far less hub and thus less wear&tear. And it sticks to metal objects, too 
Works quite good so far (except that you have to give excessive pressure on the battery connections so that it makes contact - my aluminium battery connection is that unreliable)


Now for something different:
Anybody knows where to order foil in carbon fiber look? Or other interesting patterns? The whole thing looks dull with black electrical tape. And I can't find it on my black desk...


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## balou (Dec 16, 2009)

savumaki said:


> > I also thought about renaming the project to business card light. Mainly because such a thing would make an impressive business card.
> 
> 
> If I was still in my past profession I would not hesitate to order several doz. for my 'special' customers; GREAT THOUGHT.


Looks like it would make a rather expensive business card. Part costs alone is about $10. Labor... well, if somebody wants this in a commercial setting, e.g. expecting to make a profit in the end by giving away gifts, then the total cost of the card will be in the 30$ or above range...


Btw, I also grew fond of the 1xCR2016, filed down LED idea. I will probably also make some ultrasmall _fla_ux_t_ons. Wallet rocket + emergency light.


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## Hallmcc (Dec 16, 2009)

balou said:


> Hallmcc, is that how you meant it, a bit of heat shrink tube as spring?


 
I was thinking like this:





using material like this:
http://www.batteryspace.com/78-3widthpvctube.aspx


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## Fenki (Dec 16, 2009)

Hey! I just stumbled upon this thread - and try to make my first post on CPF 

I have a bunch of switches laying arround here: They are about 1.7mm thick and 1.5 when pressed. The switch bodi itself has 1.3mm; sou you could sand the plastic knob a bit...






For I have them out of old laserpointers, I don't know what manufacturer they are from. But since you're in Switzerland, I could send you some to test. 

For the covering it may work like this:
Print out a sticker with your favorite image and stick it on the board. Then iron a piece of a laminating pouche on it. This should give a nice and durable surface


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## balou (Dec 16, 2009)

Ah, that's how you meant it. I'll have to try it.

I also thought about mounting the LED. Maybe I can mount the LED completely solderless - just a groove so that the leads of the LED sit flush with the surface of the PCB, and then just taping it with copper tape. Even if that doesn't work - the copper tape will come in handy to dissipate heat away from the LED. The Sunnix has an exposed metal area on the back, acting as the main heatsink. Coppertapping over it would allow the heat to spread over the tape and onto the copper plane of the PCB.

Concerning the flauxton: I made some quick sketches. It could be doable in just 25x32mm. You could get it smaller by using CR1216 batteries - but the size of the switch and LED is fixed, and it wouldn't make such a difference in size, but a huge difference in brightness and runtime (btw, 3 or 5mm LEDs don't make a difference. They can be filed down to the same size).
Two wallet flashlight - one the smallest size practicable (one CR2016), and the other the biggest size practicable (credit card sized).


Ok, now on to the bad news:
*Copper tape*: this whole project is pretty much on hold until I get my copper tape. Can't test new switches on the prototype if the battery doesn't have reliable contact. Will try to solder a connection for an external battery, but I also need copper tape for the switch itself.

*Machining*: doesn't look like I can speed up the tedious task of milling 20mm holes by hand at home. See https://www.candlepowerforums.com/threads/253237
This is a serious problem if I have to make 6 holes per light, and I need 5 minutes per hole. Machining it at a shop would probably require a run of 50 Clights or so.

*Safety*: Safety concerns were raised in the thread mentioned above. I won't work with the PCB anymore until I know which respiratory mask and what kind of air filtering I should use. See https://www.candlepowerforums.com/threads/253247


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## balou (Dec 16, 2009)

Hi Fenki and :welcome:



Fenki said:


> Hey! I just stumbled upon this thread - and try to make my first post on CPF
> 
> I have a bunch of switches laying arround here: They are about 1.7mm thick and 1.5 when pressed. The switch bodi itself has 1.3mm; sou you could sand the plastic knob a bit...
> 
> ...


I'm afraid that those switches probably won't work. The switch must be protected from accidental activation in the wallet. If I could file it down to 1.3mm, there still would only be 0.3mm between the switch and the surface of the pcb - to little to deter accidental activation imho.

And now again for something completely different: FR4 really is tough. I had a strip of about 2.5mm width. I tried how bendable it was. First of all, it's very hard to bend at all, and you can bend it to quite some degree until it breaks. About 45° - which you will never encounter in a wallet.


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## balou (Dec 17, 2009)

Some updates:
Purchased a 'respirable dust' mask (no idea if that's the right term, dictionary just gave that translation for 'Feinstaub'), and 3mm cylindrical cutters. According to the packaging, the mask is suitable for sanding lead-containing paint. Will hopefully also be suitable for fibre glass and phenol (it's the highest protection class they had).

That mask sure is uncomfortable - but I don't wanna end up with nonfunctional lungs.

I'm also considering changing from G10/FR4 to phenolic paper. Might be easier to machine.


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## balou (Dec 18, 2009)

Except for prototypes, I think I'm outsourcing the whole G10 machining to China.

I think I could get about 20 boards for about $200, or about $10 per board. Other components will also be about $10 total. Costs of assembly unknown - don't know how long it'll take to assemble, also no idea what a fair amount per hour would be (I'm not trying to make any big profits of this, but I also won't assemble them completely for free..)
I've thought of offering board only (for purely board price + shipping costs), complete kits and assembled lights.

Funny thing is, 3000 boards would maybe cost $3000 - a tenth of the price... Economy of scale really come into play when considering PCBs.

So the reason for this post: *this is a feeler*. Anybody interested in boards/kits/lights? Some people already posted  smileys, but I don't know how serious they were.

P.S.: I hope this post isn't against the rules. I'm trying to gauge if I should only build one single light for me, or if I should bother selling boards/kits/assembled lights in Custom&Modified B/S/T.


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## Benson (Dec 19, 2009)

Balou, if you want to accurately guage interest, you really need to start a new feeler thread, or edit this thread title to add "feeler" -- some folks who'd sign up may be skipping over this thread thinking that it's just you muddling through a project -- I know I sometimes skip build threads making slow but steady progress until I see "[BEAMSHOTS ADDED!!!!]" in the title.


As for me, if the kit is around $25, I'd be in for one or two up front, maybe a couple or three more as gifts after I build mine. Not sure about completed lights, depends on pricing and how much tweaking is possible building my own from a kit. (I'm thinking, beyond the basic card you fit in the wallet, it would be fun to embed a slightly modified version in a wallet.)

Regarding the switches Fenki suggested -- it'd be possible to glue an o-ring around the switch, so the light body is 1.6mm thick, but with maybe 2.2mm guard bulge (like a tailstanding tailcap around the switch). For me, this wouldn't be a problem at all.


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## nOObeR (Dec 19, 2009)

Have you ever visited instructables.com?
I think you may find the following instructable interesting.

http://www.instructables.com/id/Extreme-Business-Cards!/?ALLSTEPS

The premise of the instructable is more directed toward business cards but your ideas are the same.

If you look at the auto dialler section on the bottom half of the page, it is housed in a credit card so hopefully you can get some ideas.


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## nOObeR (Dec 19, 2009)

spotted another instructables artcile here that may gibe you ideas.

This one even uses copper tape, in a similar fashion that has been discussed

http://www.instructables.com/id/Flashlight_Business_Card/?ALLSTEPS


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## balou (Dec 19, 2009)

Benson said:


> Balou, if you want to accurately guage interest, you really need to start a new feeler thread, or edit this thread title to add "feeler"


Yeah, you're right. I probably also need a reliable prototype first - guess I wanted to speed this up a little.



> As for me, if the kit is around $25, I'd be in for one or two up front, maybe a couple or three more as gifts after I build mine. Not sure about completed lights, depends on pricing and how much tweaking is possible building my own from a kit. (I'm thinking, beyond the basic card you fit in the wallet, it would be fun to embed a slightly modified version in a wallet.)
> 
> Regarding the switches Fenki suggested -- it'd be possible to glue an o-ring around the switch, so the light body is 1.6mm thick, but with maybe 2.2mm guard bulge (like a tailstanding tailcap around the switch). For me, this wouldn't be a problem at all.


Hm... what kind of tweaking were you thinking about? One that comes to mind would be battery configuration - either 2s3p or 1s6p (maybe I also reduce it to 4 batteries). Embedded magnets would also be another possible tweak (might be problems with magnet stripe cards). And of course the cover design.
About that guard bulge: I think that would pose a problem in at least my wallet - the Clight would be among a stack of credit cards.

Speaking of the stack of credit cards: it probably has to be slightly smaller than a credit card, to account for the higher height. Circumference of the light should be same as a CC. This would mean 0.8mm shorter on every side.

nOObeR: I've gone through all instructables I could find. All of them are way to big, and the switch is in no way protected against accidental activation. So they are of little use for my project.


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## Benson (Dec 19, 2009)

balou said:


> Hm... what kind of tweaking were you thinking about? One that comes to mind would be battery configuration - either 2s3p or 1s6p (maybe I also reduce it to 4 batteries). Embedded magnets would also be another possible tweak (might be problems with magnet stripe cards). And of course the cover design.


Yeah, mostly battery stuff -- I think I posted about some thin Li-poly cells earlier, which (with a suitable metal skeleton) should easily work in the wallet-mod plan. Also maybe trying different emitters and such.

Not to diminish your effort in the other parts at all, but the switch is the only _really_ hard part. Once you've got a suitable switch sourced or a construction method for a reliable foil switch established, I can buy a kit and tinker with everything else (battery, emitters, and possibly adding an MCU).

Ah, one more I was thinking of -- if you run this off a 6V or higher supply, you could easily add a 5V regulator and (not so easily) convert one corner of the card into a de-shielded USB connector -- not enough juice to recharge a cell-phone or anything, but maybe run some really low-powered USB lights or fans. Bonus points if I can also allow it to charge the Li-ion cell (see above) by plugging the corner of the card into a USB port.



> About that guard bulge: I think that would pose a problem in at least my wallet - the Clight would be among a stack of credit cards.


Yeah, credit cards with embossed numbering protruding from one side about .5mm or so -- that's why I figured a similar protrusion here wouldn't be a problem, and would also guide your finger to the correct spot instead of squeezing wildly all over (at least I would). In fact, if your kit/assembled light doesn't include such a ring, I'd add that to the list of mods that, if difficult from a preassembled light, would make me buy kits instead.


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## balou (Dec 20, 2009)

Some people recommended sticking to a European or American PCB manufacturer for prototypes. sector_cleared led me to http://www.pcb-pool.com (thanks!). They could do *20 pieces for about $15 each*, or *50 for $10 each*. (and 14 pieces for the exact same price as 20 pieces!..)

*Number of batteries*: 6 CR2016 are really pushing it - there's almost no room for the switch or the LED. I'm changing to 4 batteries for the moment.

*LED*: The prototype will use a 1W Samsung Sunnix5 LED. But it's only running at 0.5W - so the LED is unnecessary bright and unnecessary expensive. I'm trying to find a better suited 0.5W LED. Projected runtime is still about 1 hour until it starts to dim noticeable, and then a couple of hours moonlight mode. 

*Optics*: Ever seen one of those telephoto lens attachments for iPhones and other cellphones? Attachable aspheric? 

*Rechargeable*: I'm beginning to reconsider it. A PGEB016144
Li-ion has 200mAh capacity and is 44x61x1mm big. I'd have to place the switch and the LED side by side, but the switch could be made with the help of an U-shaped cutout on a carbon fibre top panel. And the PCB could be reduced to 1mm size. Top and bottom carbon fibre panel could be 0.4mm each, giving a total thickness of 1.8mm. A SOT23 sized microcontroller would fit in too. Maximum drive current would be 400mA. As you see, this would be a completely different light.
But I also begin to wonder if this current design is a little to crummy - a little to unimpressive for people to want it.

An 1.8mm thick light, with carbon fibre top and bottom, 200mAh rechargeable cell, PWM controlled brightness, digital switch, keylock function to prevent accidental in-wallet activation... 

That would surely cost at least twice as much as the current design.
But again... the current project starts getting expensive for a not so impressive light, to little bling...
$40 for a PCB with 4 holes for CR2016 batteries, a pressure switch and a LED?
Or $120 for a light made of shiny Carbon fibre and hightech G10, rechargeable cell and digitally controlled brightness? :naughty:
(those are most likely kit costs, not assembled costs...)

I started the 'rechargeable' idea as a little addendum to my post... and now it's threatening my whole design 
Whaddya think, fellow flashaholics?

edit: tested both Sunnix5 LEDs with two CR2016. Surprisingly bright (at only half the projected drive level...). The coolwhite is comparable to a Cree WC tint. The warm white is really warm, a Cree 5A tint looks cool compared to it. It really is warm and not neutral how the 5A often is called.

edit2: http://www.dragonplate.com/ is offering carbon fiber CNC machining for small runs and prototypes. Might have to get a quote from them...
Concerning the cardlight: I might also do a really cheap variant - 0.5W led, copper tape, and cardboard or plastic body. This thing has either to be impulse-buy cheap or really fancy...
edit3: and 2 CR2016 only


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