I suggest avoiding the use of series string incandescent lights BECAUSE many of those strings of lights mostly include a feature that somehow bypasses the bulb's filament when the filament fails open. That would place a much lower load resistance across the supply voltage source, which could cause an unwanted load on the power source, and lead to excessive current problems.

 

Thank you for all of your kind suggestions. Sourcing from a different country is of course difficult for me. While than can be my last resort, I wanted to use parts available at local online shops only. I wanted to keep the setup compact as much as I could. After being unable to find COB or ultra bright LED, I moved forward with a generic 5mm white LED. I made this-


The light is not very eye pleasing though. I need to hold it in my hand and focus on the book.


I am open to all suggestions regarding its improvement in both electrical and mechanical term. I'd like to 3D print an enclosure with a flexible body if possible.

 

Well, I did warn you about some LEDs having a narrow viewing angle.

You might try diffusing, although I can't see that helping much.

 

Hello,

You might want to try some telux leds.
Those have an angle of about 60 degrees.

Bertus

 

Well, I did warn you about some LEDs having a narrow viewing angle.

You might try diffusing, although I can't see that helping much.

What I have found to work very well to broaden the light beam from narrow beam LEDs is to roughen the curved portion of the lens with some fairly fine sanding cloth. (That is similar to sandPAPER but it has a cloth backing. It is commonly used on powered belt sanders,, but also available as strip stock. Plain sandpaper, possiblyabout "300 grit", or near that range, should work as well. What it does is to diffuse the focused beam from the LED. I have used it on the 5mm and on the 3mm size plastic LEDs, I have no idea as to how it will work on other types of LED packages.

 

I am open to all suggestions regarding its improvement in both electrical and mechanical term.

You should use an LED with a diffused lens for better dispersal of the light.

You could also try using other colors (green or red). I once had a button cell powered red LED flashlight to use when walking around in dark movie theaters. The light was bright enough to see by, but not bright enough to bother other people.

You could reposition the LED so that it's oriented perpendicular to the board. That way you could lay the board on your shoulder/chest and direct the light at the book. I did this with a regular 3AAA LED flashlight when I was reading in a darkened room. The light was far too bright, but I directed the center of the beam off of the page.

After being unable to find COB or ultra bright LED

I think an ultrabright LED would have been overkill. Especially since you're not using a current limiting resistor.

I'd consider using a current limiting resistor/pot to cut down on the brightness (which is clearly too bright in the center).

 

I

Well, I did warn you about some LEDs having a narrow viewing angle.

You might try diffusing, although I can't see that helping much.

I actually looked for diffussing. It was not available at the shop where I purchased my parts from. Btw, may I know why you think diffused will not help either?

 

You should use an LED with a diffused lens for better dispersal of the light.

You could also try using other colors (green or red). I once had a button cell powered red LED flashlight to use when walking around in dark movie theaters. The light was bright enough to see by, but not bright enough to bother other people.

You could reposition the LED so that it's oriented perpendicular to the board. That way you could lay the board on your shoulder/chest and direct the light at the book. I did this with a regular 3AAA LED flashlight when I was reading in a darkened room. The light was far too bright, but I directed the center of the beam off of the page.

I think an ultrabright LED would have been overkill. Especially since you're not using a current limiting resistor.

I'd consider using a current limiting resistor/pot to cut down on the brightness (which is clearly too bright in the center).

Since this is for reading purpose, I think green and red will not be helpful, right?

 

Since this is for reading purpose, I think green and red will not be helpful, right?

I don't know what your eyesight is like, but I can read in a darkened room just fine with red or green light. I just tried with standard brightness (meaning <10mcd) at 20mA. Granted I had to hold them about 6-10 inches from the printed text, but I could still read it. Would have gotten better after my eyes had adjusted to the dark...

Green happens to be around the peak wavelength responsiveness for most people.

 

There is also a question in my mind like why buying if I myself can make one?

I just ordered 20 of these from AliExpress for $1.84 (I had a $4 discount on my order):

That's less than a dime each. The 3 LEDs are wired in parallel. If they're too bright, I can change the resistor. I may even swap out the LEDs with on some with red, green, or orange LEDs.

EDIT: corrected text above.

You powered your circuit with a CR2032. I'd be more inclined to use a Li-ion 16340; even though I also have CR2032, CR2025, CR2016, and CR1612 CR1216 on hand.

 

I actually looked for diffussing.

I am open to all suggestions

White card stock can be fashioned into a reflective surface. That could act as a diffuser and cast a wider area of light while at the same time reducing the harshness of the beam directed against the book page. It's a cheap test and you have virtually nothing to lose for trying.

 

I just ordered 20 of these from AliExpress for $1.84 (I had a $4 discount on my order):
View attachment 368818
That's less than a dime each. The 3 LEDs are wired in parallel. If they're too bright, I can change the resistor. I may even swap out the LEDs with on some with red, green, or orange LEDs.

You powered your circuit with a CR2032. I'd be more inclined to use a Li-ion 16340; even though I also have CR2032, CR2025, CR2016, and CR1612 on hand.

Thank you. Actually, shipping to Bangladesh adds up a lot of charges. However, there are local online shops who takes order from people and import from alliexpress. I may check with them.

 

White card stock can be fashioned into a reflective surface. That could act as a diffuser and cast a wider area of light while at the same time reducing the harshness of the beam directed against the book page. It's a cheap test and you have virtually nothing to lose for trying.

In that case, do I need to enclose the LED with white cards?

 

Actually, shipping to Bangladesh adds up a lot of charges.

I usually get free shipping from AliExpress. Either by choosing items that ship free or ordering more than $10. In this case, I ordered $50 to get free shipping, a $4 discount, $2.50 rewards from the credit card I used, and $10 back from a credit card that offers rewards on things I buy online (even if I don't use their card).

EDIT: The $50 amount was required by the credit card that offered the $10 reward. Lately I've been ordering $10-20 at a time. Prices for some/many items depend on the country they're ordered from. These items were specially priced "quick pick" items.

In that case, do I need to enclose the LED with white cards?

You can also try roughing up the surface with sandpaper. I watched part of a video where someone did that to 512 LEDs to make a cube circuit. I'd've just bought LEDs with diffused lenses.

 

Actually, shipping to Bangladesh adds up a lot of charges.

i just wanted to test it, went to LCSC and picked some LEDs
https://www.lcsc.com/product-detail/C210328.html?s_z=n_q_C210328&globalKeyword=C210328

price with shipping to Canada for 200pcs is some $15 total ($4 for parts + $3 handling + $8 shipping) for 7-15 days...
then i changed destination to Bangladesh and total is $17 for 25-40 days. so yes it does cost more and it takes longer.

 

about diffusing light... i would prefer to not have light facing me. so having head light for example would be less glare and strain on the eyes,

 

In that case, do I need to enclose the LED with white cards?

What I mean by is to act like a reflective surface. In other words point the LED at the white card and let the illumination of the card illuminate the page. And it doesn't have to shine up into your face. Experiment with a bowed card versus a flat card. Somehow the light will be reflected from the white card stock and illuminate your page.

 

I set up something the other day just to fool around with I had an 18650 powering 3 bright white LED's in parallel and then a second set of three soft white LED's in parallel within a small housing lined with tinfoil and that would dhave been bright enough for any sort of reading you had to do. It ran on an 18650 for about 10 hours but you never read that long anyway probably need to charge it every couple of days or so. Not much in components just 6 LED's and a couple of resistors.

 

I set up something the other day just to fool around with I had an 18650 powering 3 bright white LED's in parallel and then a second set of three soft white LED's in parallel within a small housing lined with tinfoil and that would dhave been bright enough for any sort of reading you had to do. It ran on an 18650 for about 10 hours but you never read that long anyway probably need to charge it every couple of days or so. Not much in components just 6 LED's and a couple of resistors.

Is there any picture of your setup? Thank you.

 

Is there any picture of your setup? Thank you.

No I'm afraid I don't. As I stated I was simply messing around while I waited for some parts to arrive for another project. All the stuff I used for it is now put back into their boxes. the whole thing was held together with spit and bailing wire because I had no intention of ever making it just seeing how bright I could make it. But the circuit is so simple. simply 2 resistors to limit current and 6 LED's each led drew about 1.2V so 3 could be handled with the 18650 just barely but it worked and then it was taken apart. That was before I read this post.