Ultraviolet Business Card Flashlight

 by tomward
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If you've seen some of my other business cards, I like the idea of giving away cards that are useful in some way.  Most of my others have been more proof-of-concept, but this one is not only fun but easy to make, inexpensive and has a real wow factor.

It's a simple ultraviolet torch, but the basic design can easily be made as a normal (white) flashlight instead, and the components only cost a couple of dollars.  I designed it originally for the Science Museum in London as an interactive workshop for kids, but the adults liked them as much as the children so I decided to keep the design as a business card.  It's a great way of advertising that you see things in a different light, particularly if you are involved in science, technology or a creative field.  If you're into making things, you might even want to give it away as a kit that recipient makes themselves.

The plain white version is also great and makes a very useful addition to somebody's wallet that they will probably not want to throw away.  The second image is a picture of a 'morse code' version as suggested by Johenix in the comments below (thanks for the great idea!).

There are lots of really fun things you can look at with UV light and the pictures above show a few of them - looking at invisible marks on things like bank notes, passports, and driving licenses, testing out how well you really  wash your hands, making things glow in the dark (the "Hi!" message was 'drawn' on glow in the dark material), making yellow highlighter ink fluoresce (the skeleton on the hand),  investigating certain bacteria, and writing in invisible ink - more about these on the last step of the instructable.  You can even go scorpion hunting (not recommended!) as they fluoresce under UV light.

I'll show you how to build them from scratch, but am also providing a complete kit for those that just want a small quantity, prefer an easier build or want to have them supplied pre-made.

I'm also going to publish this instructable at the same time as an educational version with a simpler build, and more details of how to use it in teaching.
 
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Step 1: What you'll need

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I told you this one was simple ... all you need is
  1. A couple of blank PVC ID cards
  2. A 3mm ultraviolet LED
  3. Some 5mm (or 1/4") thick foam of some sort that squishes and returns to shape again 
  4. 1 x CR2032 lithium battery
  5. If you want your own design on the front, you'll also need some way of printing on it. I used some inkjet compatible white self-adhesive vinyl.
You'll also need some way of gluing it together (hot melt glue is good) - I used some double-sided tape I had on hand.

I've put together a few links below of suggested suppliers and parts - with postage costs and minimum quantities you're probably looking at $2-$3 each if you wanted to make 100.  As I order thousands for the workshops I'm running, a couple of people have asked me if I can supply the bits, which I'm more than happy to (works out around $1.50 each (for quantities 10+) with everything you need, including the foam already laser cut, white or UV LEDs, cards, batteries and self-adhesive inkjet transfers.

UPDATE: Due to the interest I have setup a little web store to sell these kits cheaply: www.flashlightcards.com

If you prefer to buy all the bits yourself, this is what you'll need:
Adambowker98 says: Jun 6, 2012. 8:46 PM
How does the lead of the LED not touch the battery when you attach the second ID card?
tomward (author) in reply to Adambowker98Jun 7, 2012. 12:45 AM
The foam is a little thicker than the battery - this, and the previous step (spreading the legs of the LED apart) mean that they don't both touch at the same time unless you squeeze the card.
GroveCanada says: Feb 3, 2012. 4:08 PM
Dear Ultra Violet Light Business card thanks for your help from your idea & synchronized with a few other Canadians, a sauna guy & his Dad, I came up with a heated Trumpeter Swan Nest, just really a giant version of your uv biz card with a 12Volt battery portable that comes with a flashlight from Amazon, your black foam but so thick it hides the whole battery & casing, with a trip switch instead of a pressure point, & let the Trumpeter Swans figure out how to switch it on & off themselves at night, through the waterproof ink printed on white viny sandwich top...I will post the picture on the bottom of my How to make a Trumpeter swan nest Instructable now...give me a 5 to do please...
http://www.instructables.com/id/How-to-make-a-Trumpeter-Swan-Nest/
Draeyoc says: Jan 31, 2012. 2:49 PM
Shouldn't there be a current limiting resistor in the circuit?
tomward (author) in reply to DraeyocFeb 1, 2012. 1:35 AM
Well spotted! Actually we are bending the rules here but it is quite justified for a couple of reasons:

1) Typical lithium cells of this size can't source enough current for long enough to kill the LEDs (usually quite a bit over 25mA)

2) Minimal current flows through an LED anyway until you overcome their 'forward voltage drop' which is usually a little over 3V for white, blue or UV LEDs. As this is less than the cell voltage (around 3V) then we get only a small amount of current (but then again, less light than we could otherwise)
vishalapr says: Feb 1, 2012. 12:47 AM

WOW!



How were you inspired to make this?

Good Job!

jgdovin says: Jan 29, 2012. 10:06 AM
I think i will do this for our makerspace, except I am thinking of replacing one of the cards with an rfid card since our front door is rfid controlled. I think this would add some function at a small price increase.
tomward (author) in reply to jgdovinJan 30, 2012. 3:25 AM
Nice idea!
Shadetree Engineer says: Jan 29, 2012. 4:36 PM
Nice momentary switch. I'd bend the tips of the legs on the LED, so that they anchor into the foam. Angled outwards to not short against each other, of course. What about adding some EL wire to the outer edge of the card? Is there a driver small enough to insert into the foam?
Madrigorne in reply to Shadetree EngineerJan 30, 2012. 2:50 AM
EL Wire would be cool
Shadetree Engineer says: Jan 29, 2012. 4:56 PM
And finally, what about using double-sided foam tape? Could be layered if not thick enough.
Madrigorne in reply to Shadetree EngineerJan 30, 2012. 2:49 AM
awesome idea!
nwlaurie says: Jan 30, 2012. 1:30 AM
Spray adhesive - available in art shops - might be tidier (more professional?) than hot-melt or double-sided. Just make sure you get the kind that works for your materials, there are many to choose from and not all stick to everything (that's why there are many to choose from, doh!)
tomward (author) in reply to nwlaurieJan 30, 2012. 2:38 AM
Good idea - you will find though that you don't see the tape or glue when assembled , particularly as the foam rectangle is slightly smaller than the cards on either side.
epruss says: Jan 29, 2012. 8:31 PM
I was only advising to hire a professional GRAPHIC designer for that element as the benefits are well worth it. I apologise that I was not more clear in my wording.

Have a nice day all!
Shadetree Engineer says: Jan 29, 2012. 4:49 PM
Lasertag cards? Nice! That would be an awesome giftcard to a lasertag business. The giftcard should have a small laser. I've seen some 3mW red laser modules on ebay that had the lens cast in place around the diode, so it's a really small package. No link, sorry.
badmoonryzn says: Jan 29, 2012. 4:45 PM
I think your idea is great! It would be nice to have a unit that put out all of the band widths of light. Why didn't you use higher wattage LEDs? With the cost of the Chinese one, five and ten watt units at good priced I have a 1 watt UV unit and a one watt IR unit with a 5 watt white. It does a good job for not much more money.

Cheers!
ArtistZ says: Jan 29, 2012. 3:11 PM
Nice project! :D
epruss says: Jan 29, 2012. 10:14 AM
(removed by author or community request)
schmitta in reply to eprussJan 29, 2012. 2:08 PM
where and how do you contact a "Professional"?
bstott in reply to eprussJan 29, 2012. 1:12 PM
If you are piggy backing off someone else's cool contribution to the Maker community it would be a 'Nice' thing to refer to your own helpful 'Instructable' which shares additional experience and fun. Many curious Makers will find that these cool things are fun but, when doing for our own businesses they will distract from our bread and butter. What does this mean? People will hire a professional but, likely not one taking from someone else's contributions.....
Mechanic2011 says: Jan 29, 2012. 12:56 PM
Very cool idea !!
I thought about using some of the rectangular LED's so they are much thinner but they are only available in certain colors and not clear white or Ultraviolet .
Blue is the closest color to U.V. that I could find on this link.
Perhaps try Ebay


http://search.digikey.com/us/en/cat/optoelectronics/leds-75ma-discrete/524729?k=rectangular%20LED

What about incorporating one of those tiny modules that you can record a message onto like you find in greeting cards and such.
They have such a thin profile that it could work.
It would only cost you the card to get it .
We use the RFID cards at work for the secure area passkeys.
They are already about 1/8" thick but I'm not sure there is much more room inside one to add anything else to it.

waynesl says: Jan 29, 2012. 11:44 AM
I bow humbly to your simple elegance in design and execution.
jonnyd55 says: Jan 28, 2012. 12:31 AM
Hi, I have looked at all your cards...... Pretty cool. How bout these ideas?
-incorporate an EL transformer for mini electric shock?
-LDR+tranny for auto light up card in dark?
-something involving lasers?
-a mini vibro motor from a mobile phone to make a card that won't stay still?

Keep up the good work

Jonny
denswei in reply to jonnyd55Jan 29, 2012. 8:41 AM
An electric shock?? ...oooo.... an "Anti-Business Card"
You could print them with the names of your competitors.
jonnyd55 in reply to densweiJan 29, 2012. 9:54 AM
LOL :) "Anti-Business Card" very amusing
Johenix says: Jan 27, 2012. 8:13 PM
Hey, you could make a card flashlight (Torch) that had a white or red LED on one side and an ultra-violet LED on the other- a two in one.

Put the Morse Code on the blank back.

Great item for a Scout troop.
tomward (author) in reply to JohenixJan 29, 2012. 8:39 AM
What a great idea! Have just now done a version of this (see second picture on first step (introduction)). Have only done one side, but would be very easy to modify for the other LED. Are you a scout leader? I'm thinking of offering some pre-printed kits and this would make a great variation - what do you think? Let me know if you're interested.
Penolopy Bulnick says: Jan 27, 2012. 1:35 PM
Very cool :)
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