This simple and practical ultraviolet (UV) nightlight project will illuminate your home with a beautiful soft blue/green glow at night. It is also bright enough to use as a small message board during the day to remind you of those important appointments.

You can write or draw on it using a standard yellow highlighter which glows a green color. I bought a pack of various color highlighters only to find out that yellow was the only color that would glow under UV. You may want to try your luck and see if you can find any other markers that work. If you do, please post a comment and share it with the rest of us.


S A F E T Y . N O T E :

The term "Ultraviolet", is misleading when used to describe LEDs. UV LEDs actually emit "near ultraviolet" light (400nm). This narrow wavelength falls within the same, much broader, band as regular fluorescent black lights. This means that UV LEDs are completely safe and will NOT damage your eyes or give you skin cancer - no matter what you have heard or read elsewhere on the internet.






You may already have some of these parts in your junk box. If you do then your project cost will decrease.

(1) 5VDC/300mA Unregulated Power Supply (Wall Wart)
PWR1258 @ $1.49 each from BG Micro

(1) 2.1mm 2.1mm Barrel Connector Plug
#PWR1255 @ $.06 each from BG Micro

(1) 2.1mm Panel Mount Power Jack
#PWR1145 @ $.99 each from BG Micro

(2) Ultraviolet (UV) LEDs
#LED1078 @ $1.49 each from BG Micro

(1) 3mm Sintra Expanded PVC Sheet (8" X 12")
$3.25 each from Solarbotics

(1) Piece of Plexiglas (mine is about 80mm X 100mm)
Available at your local building supply

(2) 150 ohm 1/4 watt resistors

If you need to purchase these items then I can recommend these sources:

BG Micro
web site
I am only a hobbyist and I don't spend a lot of money on projects, but the people at BG Micro have always treated me like I was their most important corporate customer. That kind of service is nearly impossible to find these days. Add that to their great selection and low prices and you have a winning combination.

web site
Solarbotics is a great company with great products, but they are located in Canada. Because of this, you will need to allow a couple of extra days for shipping. You might be able to find a US source for small pieces of Sintra (less than several square feet in size) but I could not. If you do find a US source, please share it with us by posting a comment.

<p>Just got done with this project, was a ton of fun to build! The end result looks amazing!</p><p>I made a few tweaks to the project:</p><p> I went with a slightly larger plexiglass piece (8&quot; x 10&quot;) which I bought a few extra L.E.D.s for. However, it seems that even with only 10 L.E.D.s it is quite bright at night.</p><p>My plan was to put an L.E.D. every inch in the bottom, but was having trouble getting the layout exactly how I wanted (which is why in the first picture you can see a bright spot at the top). </p><p>Project difficulty: 6/10 (Solders are pretty easy, but the board is hard to work with if you don't have the correct tools).</p><p>Project time: 5/10 - Soldering the resistors took the most time, then it was just deciding how I wanted the plexiglass to sit. </p>
Matt:<br><br>That looks great. I really like the larger size. As for cutting the board, you really need a table saw. I used a razor knife to score it and then broke it on the score line. It works but leaves a bit of a rough edge. If your unit is too bright you could always experiment with it by covering some of the LEDs with black tape. Thanks for sharing.
Yeah, I wish I had a little better set up or I could have made the box look a bit better. Really like the project, thanks for the guide!
For the LED's, would something like this work? <br> <br>http://www.imaginarycolours.com/Merchant2/merchant.mvc?Screen=PROD&amp;Product_Code=LBO3mmPu-C&amp;Category_Code=BOPu&amp;Product_Count=4 <br> <br>It's a string of 20 purple LED's that are powered by 3-AAA batteries, and costs $15. According to the description, they are &quot;almost UV&quot;.
Here's what I came up with just in case you'd like to see your idea being used : I gutted an old X-Box 360 SMPS I had laying around to use as the base/stand. I used 3 U.V. L.E.D.'s just to be sure I would get the desired effect. I also used a simple power plug I installed on the back side of the base and a 5.2vDC 320mA supply. And the best markers I found were Expo NEON Dry Erase Markers. Here are a few photos of my finished product :
I forgot to add the pics ! Here they are :
David:<br><br>I love what you came up with! This is so awesome! I like your game console base idea. Brilliant! I especially like the way you drilled holes for the LEDs instead of cutting a slot for the plexiglass. That is much simpler than the way I did it. Cutting that slot was a real pain in the rear. Also thanks for the heads up on the dry erase markers. I never took the time to experiment with anything other than the yellow highlighter. I like your modifications so much I think I am going to make another one and give it to my daughter. Thank you so much for sharing the pictures with me. I wish you the best on learning more about electronics. <br><br>Thanks again,<br><br>Randy
Thanks a lot ! Another thing is the plexi glass - There were two two types at the store - The regular and the one that is supposed to hold up in outdoor conditions. I bought them both thinking the outdoor version would be better because it was just a tad bit thicker, but NOO - The regular worked far better to &quot;hold&quot; the near U.V. light.
Doesn't the outdoor stuff have a UV block?<br>Maybe that's why it is not as good - by design.
I didn't even think of that. HA ! I guess sometimes the most obvious things are the easiest to miss ! That has gotta be why it sucked. Good thinking !
And there actually is a slot for the glass .... It sits down in there right on the top of the L.E.D.'s. ... It's only about 3mm in however and I used 2 part epoxy glue to stabilize it. I had to cut little metal plates to hold the L.E.D.'s. And hopefully I'll learn quickly ... I have been in fact. My dad's degree is in electronics - He's an Electrical Engineer - He uses it every day. So I have a pretty good teacher ! Thanks Again !
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Thanks for responding ! I didn't think I'd get an answer ! I researched a bit more and found out ... Another question I've got is why not this : (5.2v-3.3v)/.03mA to find resistors needed ? 5.2v = source, 3.3v = led volt. and you know the mA. I have not been able to find an answer to this ! (Just by me researching on Google) Is there an actual explanation for why you didn't find resistance this way or is it cause this is a bit more simple and user friendly way of doing it ?
You cannot determine the resistance needed for the circuit using that method because that does not take into account the voltage drop across the resistor and the LED. Using the values you gave in your example you would come up with a 63 ohm resistor when you would really need a 173 ohm resistor. A 63 ohm resistor would allow over 80 milliamps to flow through the LEDs. That is almost three times their rating. They would fry in no time. I suggest you look up ohm's law. Check your local library for a book on basic electronics. I assure you it will be time well spent.
I guess also if I would have really paid good attention you answered this question in your reply to my question yesterday !! Ha ! Thanks Again !
That's what I came up with using the method you gave - 173. I have read and read and re-read the Ohm's Law wiki page - HA ! I think that's what I'm going to do is go pick up a book because this is all SOOOO interesting !! And THANKS for the explanation and your time !! I really appreciate it.
Also - This is a neat idea - I'm sure you've been told ! I see you've been told ! Even 3 years later ! I'm making one of these for my little sister for her b'day coming up - So thanks for the idea !!
this ones really coooool !!!!!!!
it'd be cool to adapt this to a message board format for a college dorm or something. put this thing up in your room and have the girlfriends leave you secret messages
just out of curiosity, how does this perform in light?<br />
<p>The writing is visible in normal room light during the day, but it is not nearly as bright as it is at night.</p>
I've often wondered how to do something like this.&nbsp; This is excellent work, very impressed 'young fellow me lad'
very neat, btw, highlighters ink also glows under blue leds light, u may try orange highlighters, looks cool also :)
When i first built this project, I got all excited and went out and bought a whole pack of highlighters in assrted colors including orange. I found out that yellow was the only color in the whole pack that would glow with the UV LEDs. It may be different with different brands of highlighters.
yea, i also think its brand-specific, cuz i have an orange highlighter, the brand is ( sanford liquid accent) , it glows strongly under both UV & blue leds
The ones I bought are BIC brite liners. The package says they are fluorescent but only the yellow one is with the UV LED. I will have to pick up some of the Sanford highlighters. The BIC yellow looks sort of green under UV. What color does the orange look?
it glows slightly greenish orange, try mixing your orange ones' ink with the yellow ones and see what happens, also try different combinations with the yellow but make the yellow ink more since it's the most glowing and find out the best colour for a night light or the one you like the most, keep me informed ;)
&nbsp;Try liquid highlighters
can you tell me how to make uv ink at home
I have no idea how to make it at home. Maybe someone else can help you.
Loctite FTW! not much holds metal warhammer models like it xD
I bought a pack of 2 UV LEDs at Radioshack, and it says that the FW power supply was from 3.2v to 3.8v. So, do I need any resistors?
You can power the LEDs with 2 "1.5vAA" batteries but I doubt seriously if the batteries would power the LEDs through one or two nights. This won't matter if you are planning to use the display for something besides a night light. As for whether you will need resistors - Yes you will need them. I have never used the ones sold by Radio Shack but my calculations show that you will need resistors in the 100 ohm range. They are really cheap and Radio Shack sells them as well. Best of luck and let me know how long it runs on the batteries.
Oops I forgot a vital piece of info! I wanted to power it with 2 "1.5v AA" batteries.
Can you wipe off the marks from the highlighter, or is it permanent? It would be really nice if one could wipe it off and re-write on the board, just like a dry erase board..
The marker is NOT permanent. It wipes off easily and can be re-written.
if it works out i will get a photo of it for ya. i have been for years using dry erase markers on the windows to write directions down etc...
wondering if you have found any other markers that will work on this? I drive truck, we use dry erase markers on the windshield all the time for directions. At night they are hard to read. if we could find some that could glow under U.V. light it would not be hard to make this as a 12V. instead of house hold current.
The only marker i have found that glows under the UV is the yellow highlighter. Your truck windshield idea sounds great, and is a unique application of the UV LEDs. Let me know how it works out for you.
Your highlighters would probably all glow if you used a flourescent black light instead of LEDs. Just a quick thought.
Now that I saw this, I want to make a clear whiteboard and use my flourescent black light on it. That way I could write all my evil plans on it at night!
How much did the plexiglas cost you? At my local Home Depot, the thickest piece (close to what you have, by looks) is over $25. Any suggestions?
For me, the guy gave it to me for free!
I tried this thing with foam bord, the the whole thing fell because the glass was too heavy. So I went to the carpenter and told him to make the base for me...
this would be awesome if it was simpler. otherwise cool!
I'm thinking about making mine about post-it-note size. that's basicly what it is.
Cool :)) That's wonderful
yes, yes, yes, i like it, yes YEEEEAAAAAAAAAAAA
Wow cool. I don't think tfat tehe circuit is so simple. I think i will try to make it too.

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Bio: After a career in industrial electronics I went back to college and now do DNA research.
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