HELP! 2-Volt White LEDs for a personal Swiss Army Knife project - 2016

[CkWeb]

Here is where I'm at with a personal project: I got some small swiss army pocket knives with built-in LED flashlights for a charity project. Most of these have red LEDs. I did have one with a white LED that I already gave out, not very bright, but it did light up! :twothumbs

Foolishly assuming I could find replacements to swap out the red LEDs pieces, I scoured the web for them but only found white LEDs inside other pocket knives! A brighter 3.3v 3mm white LED is available for these knives but it requires different types of parts and only batteries and the outside transparent scales, or sides, of the knives are sold as replacements. Also, these translucent knives come in many colors while the newer brighter ones only come in red, blue and silvertech.

Now, I'm attempting to find just compatible white LEDs to swap the red ones. I came across someone who luckily found some 2v 3mm 20mA white LEDs on eBay that worked, but the seller is not active anymore. I am assuming that more sellers must carry similar products. I'm not expecting a very bright LED light, but as long as it lights up, I'd be happy.

Here's a related link from way back, 12 years ago: http://www.candlepowerforums.com/vb/showthread.php?46237-Swiss-Army-Knife-with-LED

Here's the defunct ebay listing: http://www.ebay.com/itm/Small-LED-Ultra-Bright-White-3mm-2-pcs-Resistors-/170476739422

Here's the link I found the ebay listing: https://jethomson.wordpress.com/201...e-the-led-in-the-victorinox-midnite-minichamp

I appreciate any ideas and possible part sources that may be available for these! :twothumbs

 

[SemiMan]

Here is where I'm at with a personal project: I got some small swiss army pocket knives with built-in LED flashlights for a charity project. Most of these have red LEDs. I did have one with a white LED that I already gave out, not very bright, but it did light up! :twothumbs

Foolishly assuming I could find replacements to swap out the red LEDs pieces, I scoured the web for them but only found white LEDs inside other pocket knives! A brighter 3.3v 3mm white LED is available for these knives but it requires different types of parts and only batteries and the outside transparent scales, or sides, of the knives are sold as replacements. Also, these translucent knives come in many colors while the newer brighter ones only come in red, blue and silvertech.

Now, I'm attempting to find just compatible white LEDs to swap the red ones. I came across someone who luckily found some 2v 3mm 20mA white LEDs on eBay that worked, but the seller is not active anymore. I am assuming that more sellers must carry similar products. I'm not expecting a very bright LED light, but as long as it lights up, I'd be happy.

Here's a related link from way back, 12 years ago: http://www.candlepowerforums.com/vb/showthread.php?46237-Swiss-Army-Knife-with-LED

Here's the defunct ebay listing: http://www.ebay.com/itm/Small-LED-Ultra-Bright-White-3mm-2-pcs-Resistors-/170476739422

Here's the link I found the ebay listing: https://jethomson.wordpress.com/201...e-the-led-in-the-victorinox-midnite-minichamp

I appreciate any ideas and possible part sources that may be available for these! :twothumbs

Lithium batteries in that size are typically 3.2V nominal and many white LEDs will work with them.

 

[CkWeb]

Lithium batteries in that size are typically 3.2V nominal and many white LEDs will work with them.

I went ahead and opened up my led tools and took some images to show:

- what the three led board types look like
- to turn both white leds on for comparison
- compare batteries
- show which led tool had the smaller white led
- show a usb memory made by the same mfg. of the newer white led

I noticed immediately that the older white led board has circuitry on it that the red led board doesn't. This may explain why I found the post talking about using a lower-powered white led to swap the red leds and why some people had trouble getting their white leds to turn on when connected to the red led boards.

Hopefully these images can shed some light on the situation, maybe even find out who makes or made some of these tiny led boards!

led board comparison

newer white led front

newer white led back

older white led board

white led light comparison

led battery comparison

tool that contained older white led board

memory made by same mfg. that made newer white led board

 

[Lynx_Arc]

White LEDs have a Vf over 3v so running them direct drive at 2v you will lucky to even see them glowing looking directly at the emitter as the drive voltage is just too low. The "boards" that are used to drive the white LEDs probably have boost circuitry on them (DC to DC boost converter) that step up the ~1.4v to 3.5v or so and/or use lithium 3v batteries also as direct drive with a 3v lithium battery will light up these LEDs but they won't be full brightness perhaps 1/4 to 1/3 brightness on a new battery.

What you will have to do most likely is find a very small cheap 1 or 2AAA led light and take the boost circuit out of it and transplant it in place of the red non boost boards or switch to lithium batteries (3v) if possible

 

[Lynx_Arc]

If something like this would fit then you could use it instead. Be sure to carefully check dimensions.
http://www.ebay.com/itm/DC-DC-0-8-3V-to-3-3V-Step-UP-Boost-Power-Board-Module-Converter-Voltage-RF-/282029936915?hash=item41aa4b5113:g:3GAAAOSw1DtXLS7Q

If you are going to use this I would try it with a junk LED first and measure the output so as to not fry a good LED. I see there are 5 packs of these without the pins. I've not tried any of these boards so YMMV.

 

[CkWeb]

White LEDs have a Vf over 3v so running them direct drive at 2v you will lucky to even see them glowing looking directly at the emitter as the drive voltage is just too low. The "boards" that are used to drive the white LEDs probably have boost circuitry on them (DC to DC boost converter) that step up the ~1.4v to 3.5v or so and/or use lithium 3v batteries also as direct drive with a 3v lithium battery will light up these LEDs but they won't be full brightness perhaps 1/4 to 1/3 brightness on a new battery.

What you will have to do most likely is find a very small cheap 1 or 2AAA led light and take the boost circuit out of it and transplant it in place of the red non boost boards or switch to lithium batteries (3v) if possible

From the images, that's exactly what the white led boards look like.

The newer boards are much brighter and the bulbs are slightly bigger, but they do fit very snugly. The board itself fits the older plastic scales, so the only issue of using these is the battery size. The smaller battery does power the bulbs, but the light shines less than the older led boards.

Could they make smaller-sized batteries that have the same output as these larger ones even if they last less?

This in a way would actually solve my problem; then I would just need to cannibalize the newer boards off used tools and put those into the older tools. :thumbsup:

 

[CkWeb]

If something like this would fit then you could use it instead.
http://www.ebay.com/itm/DC-DC-0-8-3...936915?hash=item41aa4b5113:g:3GAAAOSw1DtXLS7Q

If you are going to use this I would try it with a junk LED first and measure the output so as to not fry a good LED. I see there are 5 packs of these without the pins. I've not tried any of these boards so YMMV.

These are really, really close to mark! :thumbsup:

The problem is the non-existent space within the scale itself. Eyeballing the scale, it has about one millimeter space inside, which is probably why they made the circuitry so tiny on all of these! It might be more feasible to sand down the battery area to squeeze the larger battery of the newer leds in.

I'm thinking that perhaps a battery with a little more umph but the same size as the small ones and a little less power than the large ones would give about the same output if the newer boards are swapped into the older cases. I say this because the newer tool lights are brighter and found a little more easily online than the old ones.

Ps. If the original manufacturer of the old ones would just be identified, I'd buy a few dozen boards!

 

[CkWeb]

Lynx, I used the link you posted as a guide and I found other tiny models, although I'm not sure about their dimensions are compared to the tiny width and length inside the scale. I made notes on each one - number one and four look really good size-wise and resemble the circuitry of the led boards I have:

1. without the legs, this one would fit inside the led scale:
http://www.ebay.com/itm/DC-DC-Boost...-3V-Step-Regulated-Charge-modul-/222149373182

2. this one's similar to the first one with the output leg issue, but might be just a wee bit too high:
http://www.ebay.com/itm/Tiny-size-1...tep-Up-Boost-DC-to-DC-Converter-/281789096301

3. it looks small enough, but might actually be too wide, I couldn't interpret the datasheet's dimensions:
http://www.ebay.com/itm/3-3V-Boost-Regulator-Board-MCP1640T-/262477261665?hash=item3d1cdd2b61

4. this one's also small enough with the output legs removed:
http://www.ebay.com/itm/Micro-0-8-5...-Up-Step-Down-Voltage-Converter-/142022069438

5. this one's internals may work but they may be a little too tall:
http://www.ebay.com/itm/3-3V-200mA-...t-Mode-AAA-Battery-Power-PM-1033/261889820093

6. I also found one that closely resembles the led board of the newer and brighter leds:
http://www.ebay.com/itm/DD0505MC-3-...ep-Up-for-Arduino-Breadboard-RF-/282055722086

7. if I was sure I could make these fit, I would get these x10 boards!
http://www.ebay.com/itm/10x-DC-DC-B...V-for-Zigbee-Wifi-Bluetooth-LED-/331594775517

The inside cavity of the older scale is 1mm high by 1cm wide x 1cm long. The actual height within the scale is about 1.75mm, but it has two .5mm ridges that may need to be sanded down.

Ps. If I could make last one fit the older scales, all I would need would be a higher output battery the size of the smaller lower output batteries used by the older leds!

 

[Lynx_Arc]

#1 may not operate on a 1.5v battery
#2 looks ok but $5 shipping is nuts.
#3 looks ok
#4 looks like they mislabeled it as I see no inductor which is needed for a boost circuit
#5 may be too big as it looks like a board that I bought several of and it is 18mm shortest of WxD
#6 also I cannot see an inductor and the voltage range is too low for 1 1.5v cell
#7 is the same board makup as others here.

It is possible one of the components on the boards that look like they have no inductor (coil) is an inductor that to me looks like a diode as I've not seen all the smd components ever made out there. If you are using a 1.5v cell and boosting it with a circuit that is rated 1.8v it may operate fine at low output or not operate at all, or operate ok when the battery is new and dim quickly before the battery is fully depleted it shuts off. I bought a cheap 2AAA led light off ebay that had a small boost circuit that I adapted for use in a #222 bulb socket to drive an LED off a single AAA battery and it worked well enough.
I don't see the exact model I got but I'm guessing this one has a similar design
http://www.ebay.com/itm/Medical-First-Aid-LED-Pen-Light-Flashlight-Torch-Doctor-Nurse-EMT-Emergency-/182093503187?hash=item2a659e5ad3:g:Q14AAOSwiYFXEEsq
It looks like it is driving a single 5mm LED so either it will be dimmer on 1.5v and work ok or you may have to give it away but for 99 cents you could try one out and see what the guts look like. Walmart has cheap 1AAA penlights that take a 5mm LED that may have the guts you need also just make sure and get one that does take 1AAA and not 3-4 button cells.

EDIT: I forgot I put that 2AAA circuit in a pelican 2AAA incan light with an LED instead of that #222 socket but I did try that circuit off 1AAA and it is about as bright as 2AAA in use. I could try it off a button cell if you want me to.

 

[CkWeb]

Thanks for your great breakdown analysis, Lynx!

I came across a different little board that is quite tiny and it looks like it's overkill. Still, the circuitry is so minute I had to share it and the product ordering page it's on:

1 - board description - https://www.circuitsathome.com/dc-dc/low-cost-step-up-down-120ma-dc-dc-converter
2 - store order page - https://www.circuitsathome.com/products-page

Thanks for the led light pen link, I'll order it even if it doesn't arrive before I travel but it will give me something to tinker with!

The smaller button cell battery I was asking for doesn't exist, silly me! I looked up cell batteries and it turns out there aren't that many tiny sizes to choose from..

 

[Lynx_Arc]

Thanks for your great breakdown analysis, Lynx!

I came across a different little board that is quite tiny and it looks like it's overkill. Still, the circuitry is so minute I had to share it and the product ordering page it's on:

1 - board description - https://www.circuitsathome.com/dc-dc/low-cost-step-up-down-120ma-dc-dc-converter
2 - store order page - https://www.circuitsathome.com/products-page

Thanks for the led light pen link, I'll order it even if it doesn't arrive before I travel but it will give me something to tinker with!

The smaller button cell battery I was asking for doesn't exist, silly me! I looked up cell batteries and it turns out there aren't that many tiny sizes to choose from..

Interesting.... it says no inductor needed maybe one is built into the chip? Maybe the other ebay ones use a similar chip. I will say one thing in that most of these boards you've listed will output more than a 3mm LED can handle so you will end up having to modify the output somehow to a lower current output preferably changing the sense resistor so it draws less current from the battery and outputs less current to the LED. I would recommend about 10ma output to the LED should be bright enough and running it closer to 20ma would use up the lithium battery (I assume that is what you will be using) a lot faster.

 

[CkWeb]

Here are some side shots of these boards, I also found out I had a laser pointer in the mix! Of course, that one uses the larger batteries also but the older and smaller tool scales and boards need to use the smaller batteries because those don't have enough room for the larger batteries.. :sigh:

 

[CkWeb]

Can I use the smaller 399 (927) in place of the 389 (1130)?

Lynx, here are the two ways I've thought of doing the same thing, which is adding a white led light to the older Swiss tools I am modifying:

The high-tech solution: this entails swapping out red leds for white ones and wiring a circuit board to the older led boards within the 1cm x 1cm x 1.25mm-1.75mm gap inside the older scales using low power cr1025 3-volt batteries
Biggest challenges: low battery power and very limited room to add the booster boards

The low-tech solution: this requires acquiring the newer led boards and somehow fit their larger batteries inside the older scales
Biggest challenge: there simply isn't enough room to fit a 1130 battery inside the older scales

However, I've found a battery small enough to fit the older enclosures and still power the newer led boards.


My question is would it have what it takes to power the newer boards?

Here's the smaller battery I'm referring to: http://watchbatterycrossreference.com/pdfs/R399.pdf
Here's the battery it would replace: http://watchbatterycrossreference.com/pdfs/R389.pdf

Outside of the dimensions, the three main differences are:

1. The smaller batteries have a 55mAh capacity versus the 80mAh of the larger ones
2. instead of discharging over 15 kΩ, this smaller battery discharges over 18,2 kΩ at 20°C to 1,2 V
3. the starting drain of the original battery is 104 µA and the newer battery's starting drain is 85,7 µA

I'm weighing the technical difficulty of swapping leds, adding circuitry and using a possibly lower power battery (the cr1025) versus buying used tools to take their newer led boards and these smaller batteries. Outside of costing more, the only other disadvantage I can think of is shorter battery life.

Do you think these would work?

 

[Lynx_Arc]

Re: Can I use the smaller 399 (927) in place of the 389 (1130)?

The 389 battery (larger) is also an AG10 battery which are not too hard to get cheaply they may not run as long as the silver oxide variety but you can buy them in 5 packs for $1. I just took the circuit/led board that I scavenged out of the cheap 2AAA light I got off ebay and used an AG10 battery on it and it draws about 80ma and is pretty bright. Now there is a boost of about I'm estimating 1.3v to 3.5v or 3 times the current to raise the voltage so I'm guessing with losses the LED is getting perhaps 15-20ma. If you could drop that drain down to about half or 1/3 of that amount by swapping out a component like maybe the inductor or sense resistor it may work just fine for about 1 hour perhaps total runtime which is acceptable.
Don't hold me to any of these figures though just sort of guestimating.

 

[CkWeb]

Re: Can I use the smaller 399 (927) in place of the 389 (1130)?

Thank Lynx; your estimates on the 389 are very well thought out!

The 389 batteries are what the newer leds I have use. The issue with the 389 batteries is they're too big for my older swiss tools to hold inside. The 399 model is a lot smaller and holds about 70 percent of the charge of the 389, but I have no idea if any differences in the 399 battery may cause any issues, you know? They seem nearly identical based on the spec sheets I posted:

the 389 spec sheet - this is the one I can't fit inside the older tools
the 399 spec sheet - this is the one I want to get to test to see if and how well it works

I really appreciate your research into this; you really know your stuff! I am learning so much :thumbsup:

 

[Lynx_Arc]

Re: Can I use the smaller 399 (927) in place of the 389 (1130)?

I really can't help you that much on battery dimensions but you could look at this renalt battery gauge chart that you slide cells into sideways. The battery you are looking at I believe is also known as AG7. I use the AG numbers because the alkaline batteries you get from China has that number stamped on them usually If you were going to buy these batteries in bulk for cheap that would be the way to go otherwise you can end up paying $2-$5 a battery in stores if they even carry them vs 5 for $1-2 or less.

 

[CkWeb]

Game Plan

Thanks for all of your insightful input, Lynx!

Based on everything we covered so far to get white leds into the older tools I've collected, I will:

- get and test the AG7-sized batteries to see how well they work with the new leds inside the older tools
- keep an eye out for the mythical 2-volt leds that brought me to the forums in the first place
- once I return from my trip, I will test the board from the white led pen you showed me and post my results here
- try to locate the manufacturer (mki) who built the original boards to see if they can sell replacement led boards
- get the tools needed to work on the tiny boards we found online, order a few, get some white leds and work out how to lower the mA output board mod needed

The easier solutions to my issue of course cost more because I am scavenging used tools online and they cost no less than $12-20 each. Of course, I can resell these with the red leds boards and recoup part of my investment, but it's a lot of work. Still it's a good low-tech way to mod these tools. this is only doable if the batteries actually work. Finding the original board makers who actually'd be willing to sell replacements would be phenomenal since my cost would be lower (maybe). They may charge a markup on the new boards. I'm surprised that sellers advertised a 2-volt battery that someone said they used to replace the red leds. I'm sure the light output must have been low since the red boards have no circuits whatsoever, just the battery and on switch. Getting a pen light is a brilliant idea because what they have inside may actually be small enough for me mod into the tools I have plus it gives me a white led, both for a dollar each shipped! Of course, working on these boards means I have to play with the electronics themselves, which is both exciting and overwhelming given my lack of hardware modification experience. Still, it will make for a fun exercise once I get the tools and courage to try that out. When I do so, I will definitely post my adventures here for sure!

Lynx, your expertise in this subject matter has definitely been invaluable, thanks for everything my friend! :thanks:

 

[Lynx_Arc]

Re: Game Plan

Thanks for all of your insightful input, Lynx!

Based on everything we covered so far to get white leds into the older tools I've collected, I will:

- get and test the AG7-sized batteries to see how well they work with the new leds inside the older tools
- keep an eye out for the mythical 2-volt leds that brought me to the forums in the first place
- once I return from my trip, I will test the board from the white led pen you showed me and post my results here
- try to locate the manufacturer (mki) who built the original boards to see if they can sell replacement led boards
- get the tools needed to work on the tiny boards we found online, order a few, get some white leds and work out how to lower the mA output board mod needed

The easier solutions to my issue of course cost more because I am scavenging used tools online and they cost no less than $12-20 each. Of course, I can resell these with the red leds boards and recoup part of my investment, but it's a lot of work. Still it's a good low-tech way to mod these tools. this is only doable if the batteries actually work. Finding the original board makers who actually'd be willing to sell replacements would be phenomenal since my cost would be lower (maybe). They may charge a markup on the new boards. I'm surprised that sellers advertised a 2-volt battery that someone said they used to replace the red leds. I'm sure the light output must have been low since the red boards have no circuits whatsoever, just the battery and on switch. Getting a pen light is a brilliant idea because what they have inside may actually be small enough for me mod into the tools I have plus it gives me a white led, both for a dollar each shipped! Of course, working on these boards means I have to play with the electronics themselves, which is both exciting and overwhelming given my lack of hardware modification experience. Still, it will make for a fun exercise once I get the tools and courage to try that out. When I do so, I will definitely post my adventures here for sure!

Lynx, your expertise in this subject matter has definitely been invaluable, thanks for everything my friend! :thanks:

I'm glad I've been of some help. I spent a lot of time trying to get by on the cheap when I had almost no money at all for a long time buying cheap lights and scavenging parts to make what I had work better. If there was a decent market for these boards I'm sure a chinese maker would get involved. One other thing you could consider is if you can find any 1D energizer lights with the dropins the circuit in them may be of use to scavenge a boost circuit from. The energizer lights were about $2.50 each but I think they may be out of production replaced by an SMD version which may or may not be useful in your case. Just about any 1 cell LED light will have a boost circuit in it and some 2 cell versions may also be good for boosting 1 cell too but often flashlights with round barrels and reflectors have round circuit boards that may not work well in your rectangular situation.

 

[Lynx_Arc]

Re: Game Plan

duplicate post.