# Trying to build an LED light that will clip onto my glasses



## dothedu (Mar 20, 2012)

Hi everyone, this is my first time here on this forum. I joined because I was trying to build an LED light to clip onto my glasses (dental loupes) but couldn't find the appropriate resources elsewhere.

Here is a pic that shows what I mean. I know, it costs $700, that's why I thought why can't I just build one for around $50?







Basically it consists of an Li Ion rechargeable battery pack with a dial for light intensity. It has a connector via a wire that power the actual LED in a small housing. The application for it is I can clip it onto my glasses and have a focused beam onto a patient's teeth. The spot size is about 3" at 14" distance. The illumination I'm shooting for is around 3750 FC at 14" distance. Color temp around 6000K. And I want to build the housing for the LED to be as small and light as possible.

Can anyone point me in the right direction as to how I can start building this? I've been looking at parts online but there are so many different LED's types that I didn't know where to begin. I'm hoping some veterans here might be able to answer this.

Thank you so much!


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## Steve K (Mar 20, 2012)

As an electrical engineer, I'm more inclined to just build my own circuits, but why not go to someplace like LEDsupply (http://ledsupply.com/) to get a suitable LED, optic, and driver? They have a nice spot on the upper left of their home page that provides guidance as to what sort of driver to use.
http://ledsupply.com/led-resource.php

Using the selector guide, it looks like you could use a basic white 3 watt LED like the Cree XP-G with a 3021 model Buckpuck driver, and just use 6 AA NiMH cells to power them. The version of the 3021 with the external dimming potentiometer would be best for your application. A quality potentiometer and battery holder could be purchased from a source like Mouser or Digi-key. Might want to buy suitable wires, soldering equipment, etc. from them too. Looking at the Buckpuck datasheet, it looks like a capacitor is needed at the input to the Buckpuck. 

LEDSupply sells optics for the LED too, and even Digi-key and Mouser sell some optics for Cree LEDs. You may want to buy a few versions, in order to figure out how wide you want the beam to be.

If you are new to electronics, I'd recommend buying at least a couple of drivers and LEDs. You'll probably destroy at least one set of hardware while learning.

If you can get this to work, you'll have fun and be happy that you saved money. If you can't get it to work and waste many hours and much money in electronics, you'll at least feel much more justified in paying $700 for a light that you can just buy and use. 

good luck,
Steve K.


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## dothedu (Mar 20, 2012)

Thanks so much for your advice, I'm currently buying 2 of everything, hah.

About the potentiometer, I did a search on Mouser and there were so many to choose from. I have no experience in this so is there one that you would recommend?

And as for the battery pack, I was thinking of getting these premade ones since building my own battery pack is outside of the scope of my knowledge at this point.










But both of these do not have a dimmer switch, could I add that on or do you think building from scratch would be better? There is this one on LEDSupply http://www.ledsupply.com/03021hep.php
as well as this http://www.ledsupply.com/03023-d-e-700p.php Which is the appropriate one for my application?

And how come you opted to go for NiMH instead of LiIon? Does one lasts longer than the other?

I was also looking around online for newer LED's and found the Artavi line from Illuminex (http://www.led-professional.com/pro...rowest-beam-angle-and-fully-integrated-optics). The dimensions are larger than what I envisioned but it does come with the housing/optic at the beam angle I want. So I was thinking of buying one of those and hooking it up to the battery/potentiometer and see how it looks.

I'm actually excited about this project although I know nothing about electrical engineering (I was a biology major).

Thanks again for your help and I apologize if I have too many questions.

Cheers,

Du


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## RoGuE_StreaK (Mar 20, 2012)

Without being ridiculous, could you just "redeploy" a flashlight? ie., take the head and mount it, and run cabling to the body for the battery pack?
Perhaps something like DX SKU 14228 from dealextreme, $13 or so for an adjustable beam, throw in another $10 for a pair of lipos and another $10 for a chager, and you've got your whole setup?


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## dothedu (Mar 20, 2012)

RoGuE_StreaK said:


> Without being ridiculous, could you just "redeploy" a flashlight? ie., take the head and mount it, and run cabling to the body for the battery pack?
> Perhaps something like DX SKU 14228 from dealextreme, $13 or so for an adjustable beam, throw in another $10 for a pair of lipos and another $10 for a chager, and you've got your whole setup?



That could work actually. But my main concern is the size and weight of the flashlight head sitting on top of my glasses. And do you have any suggestion as to where I can find a premade battery pack with a dimmer switch?

Thanks a lot!


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## MikeAusC (Mar 20, 2012)

If you do a search here for Dental Light you will see very long threads going into great detail of optical and thermal design.

Just don't bother offering a free light for anyone who helps you develop the design - a few of here have fallen for that . . . . and learnt the hard way that once people have the info they want they disappear.


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## dothedu (Mar 20, 2012)

Steve K said:


> As an electrical engineer, I'm more inclined to just build my own circuits, but why not go to someplace like LEDsupply (http://ledsupply.com/) to get a suitable LED, optic, and driver? They have a nice spot on the upper left of their home page that provides guidance as to what sort of driver to use.
> http://ledsupply.com/led-resource.php
> 
> Using the selector guide, it looks like you could use a basic white 3 watt LED like the Cree XP-G with a 3021 model Buckpuck driver, and just use 6 AA NiMH cells to power them. The version of the 3021 with the external dimming potentiometer would be best for your application. A quality potentiometer and battery holder could be purchased from a source like Mouser or Digi-key. Might want to buy suitable wires, soldering equipment, etc. from them too. Looking at the Buckpuck datasheet, it looks like a capacitor is needed at the input to the Buckpuck.
> ...




Thanks so much for your detailed advice. I was looking up all those parts you've mentioned and added 2 of each to my cart. I'm just not sure about the potentiometer. There is a Buckpuck 3023 version that has a potentiometer (http://www.ledsupply.com/03023-d-e-350p.php), would this be better? I tried to look for a potentiometer on Mouser and got overwhelmed by how many different ones there were, and I have no idea which to use.

As far as the battery goes, I was just thinking of buying premade battery packs like these:

http://imageshack.us/photo/my-images/593/batterypack.jpg/
http://imageshack.us/photo/my-images/15/batterypack2.jpg/

Although they don't have a dimmer switch, would it be feasible to add one? Or should I try to build the rechargeable battery pack from scratch? Also you recommended NiMH instead of LiIon, is there a reason for this?

I was also looking up newer LED's and found this, it is a little bigger than I wanted, but it might be worth buying just to test out how it will look like. 

Again, thank you so much for your help. As you can see I have no experience in electrical engineering, I was a biology major. But I like to build things and I always want to learn new things (I built my first laptop 5 years ago from online forums and am now building a desktop).

Cheers,

Du


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## dothedu (Mar 20, 2012)

MikeAusC said:


> If you do a search here for Dental Light you will see very long threads going into great detail of optical and thermal design.
> 
> Just don't bother offering a free light for anyone who helps you develop the design - a few of here have fallen for that . . . . and learnt the hard way that once people have the info they want they disappear.



Thanks for your advice, but I intend to only build one for my own use. I just think the sales people who come to my school trying to sell these lights at such outrageous prices are out of their minds.


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## dothedu (Mar 21, 2012)

Found another battery option. What do you guys think?


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## Harold_B (Mar 21, 2012)

As Mike suggested, this one specifically came to mind: http://www.candlepowerforums.com/vb/showthread.php?313013-Just-started-a-dental-flashlight-project


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## Steve K (Mar 21, 2012)

dothedu said:


> Thanks so much for your detailed advice. I was looking up all those parts you've mentioned and added 2 of each to my cart. I'm just not sure about the potentiometer. There is a Buckpuck 3023 version that has a potentiometer (http://www.ledsupply.com/03023-d-e-350p.php), would this be better? I tried to look for a potentiometer on Mouser and got overwhelmed by how many different ones there were, and I have no idea which to use.



I'm not very familiar with the whole Buckpuck family of drivers, but both the 3021 and this 3023 are available with an internal adjustement potentiometer or for use with an external potentiometer. If you want to change the settting as much as you would adjust the volume on a radio, then you'll want to get the version that uses an external potentiometer. You can find this bit of text in the driver's datasheet:

"The potentiometers used for the on-board adjustable units are rated for a limited number of rotations (typically
100) and are intended for "set it and forget it" applications. Where frequent adjustments of output current are
needed, the use of units with external adjustment capabilities is recommended."




dothedu said:


> As far as the battery goes, I was just thinking of buying premade battery packs like these:
> 
> http://imageshack.us/photo/my-images/593/batterypack.jpg/
> http://imageshack.us/photo/my-images/15/batterypack2.jpg/
> ...



I haven't played around with LiIon batteries yet... NiMH have been fine for my applications. As long as your chosen LiIon has proper protection circuitry to keep it from being over discharged, it might be fine. I'm really not the person to ask, though.



dothedu said:


> I was also looking up newer LED's and found this, it is a little bigger than I wanted, but it might be worth buying just to test out how it will look like.




I'm not familiar with this company or LED, but it might be fun to buy one and play with it. Having the LED packaged with the optics does make life a little easier. The only thing that makes me worry a bit is that the datasheet is marked "preliminary". That usually means that the part isn't in production yet, and the specs may not be accurate.
The part of the datasheet that concerned me a bit is that it's not as efficient as some of the parts from other LED suppliers. This is usually in terms of lumens per watt. They list the better ones as 163 lumens at 700mA. The LED forward voltage is around 3.3v. At 3.3v and 700mA, the power is 2.3 watts. The lumens per watt is therefore 163/2.3, or 70 lumens/watt. The Cree XP-G LED is closer to 120 lumens/watt. 

The efficiency number becomes more important when you consider how much aluminum is needed to produce a heatsink to get rid of that power. A more efficient LED will produce less heat for a given light output, and will be able to use a smaller heatsink.
In defense of the Illumitex LED, their number may include the losses in the optics, so maybe that's where the lower efficiency comes from?

As far as potentiometers.... the Buckpuck datasheet calls for a 5 kohm (i.e. 5000 ohms) linear potentiometer. This is fairly conventional, so you have a lot of options. The current though the potentiometer is low (5mA), so you can use pretty much any potentiometer. 
This is a basic panel mount potentiometer from Mouser that is a good starting point:
http://www.mouser.com/ProductDetail...=sGAEpiMZZMuarXojuOTsc7XUj8Kk/1TsuyQfgVm1Ues=

regards,
Steve K.


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## dothedu (Mar 21, 2012)

Awesome, thank you so much for all your inputs everyone!

As far as buckpuck goes, I opted to get this one which included the potentiometer. And I'm going to try a Luxeon LED as well and see the difference in real clinical settings. I will go for this battery, I was thinking of opening it up and mod it so I can use the buckpuck/potentiometer and a dial to dim the light.

This is my other cart. It looks like I have everything I need to build the first prototype loupe light.

I'll post pics of the prototype once I get the parts and start building.

Again, thank you for all your help!

Du


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## dothedu (Mar 22, 2012)

Nutty, the housing is back ordered until the 29th =(


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## Optical Inferno (Mar 29, 2012)

Just one more thought...fiber optic?? Very light weight and you can run the light source from your hip separate from the glasses. Thus not heating up your nose and forehead. Just a thought.


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## dothedu (Mar 29, 2012)

Hmm, so if I use fiber optics, that means the actual LED is where the battery pack is? And the only thing sitting on top of my glasses is the lens and wire right? Do you have any suggestions as to where I could look up and purchase some fiber optics?

Thank you!


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## PhotonFanatic (Apr 1, 2012)

dothedu said:


> Thanks for your advice, but I intend to only build one for my own use. I just think the sales people who come to my school trying to sell these lights at such outrageous prices are out of their minds.



Well, you obviously have no idea of the rules and regulations, and the costs to meet them, that medical device manufacturers face. :devil:

It's a completely different story if you are making one for your own use versus making them to sell to other dentists. 

It is a fun project though, and you will learn a lot, and probably get exactly what you want in the end--and at a cost less than $700, for sure.


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## Optical Inferno (Apr 2, 2012)

www.fiberopticproducts.com

Not to bad selection and have pretty much everything for a general hobby. However I do agree with the previous post in that there are regulation for medical apparatus like this. 

But go ahead and play and you should come up with a unique light that should work well.


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