Introduction: Extreme Business Cards

I bet nobody has given you a business card before that actually dials you up by itself! Read on to find out how I did it ....

Do you like making things? Do you do it for money, or would like to? If so, you need a business card. These can be your best advertising, but we all know business cards are boring and get thrown away. I have toyed with plastic or etched stainless cards before - these are really cool, but cost a lot, and are not really distinctively "you".

Do you make goods out of leather? Then make a leather business card. Do you make handmade greeting cards? Then make your business card look like one of these! Even better, make one that is actually useful for whoever you're giving it to, so it CAN'T be thrown away. I'm into making electronics, so what better way to advertise my skills than an electronic business card. Here are two experimental "extreme" business cards that are almost impossible for someone to throw away - one in the form of a key ring torch and one card that actually dials me up by itself! This one has a computer inside with more processing power than took the first astronauts to the moon (No, I'm not kidding!), yet the main part costs less than 50 cents. I'm also working on one that plugs into a USB port on a computer so that people can email me directly from a link, or look at a portfolio of my work.

Even if these ideas don't grab you, maybe they'll fire your imagination to think how you could make a truly unique card that uses your skills and tells people how creative you are.

Step 1: The Torch

I won't kid you - these two cards need some serious construction skills, and are both experimental (particularly the dialler), so are no beginners projects, but wait 'til you see the face of the first person you give one of these to! Don't try these designs unless you have successfully made a few electronic items before - they need good soldering skills, and ideally a way of making some printed circuit boards, although if you soldering skills are REALLY good, and you are making just a few, it is possible to make versions of both of these cards without circuit boards, and just "point to point" wiring - my prototypes were done like this.

Firstly the torch. This is the easier of the two. Although you could use some PVC cards to enclose a hand-wired version (keep reading on to see this technique used in the "dialler"), making copies is much easier with a proper PCB. A tutorial on how to make a PCB is beyond the scope of this article, but if you haven't tried it before, it is a really good technique to be able to do and opens up a countless variety of electronic projects. Here is an instructable on a simple toner transfer PCB - personally I find more repeatable and professional results with the photographic method - couldn't find an instructable for this one, but there is plenty of info on the web - I use a very cheap 500W halogen light from the local hardware store to expose mine for a few minutes, and then develop, etch and tin. If there is enough demand, I might get some universal "torch" and "dialler" boards commercially made.

Anyway, assuming you can get a PCB made up, the file which I used is included below - this can be modified on a standard graphics package. If you can't read EPS files, then try the 300dpi bitmapped version included below as well. You can of course use a specialised PCB package, but I wanted an unusual cursive font on mine, so just hand-drew the design on a graphics package. This allowed me to incorporate my name into the actual circuit board - the electric current actually goes though my name! If you want to produce a reasonable batch, you will probably want to tile your image over the page after you have made your changes.

Step 2: The Torch Parts

Here you can see the parts - a PCB, coin cell (CR2032), a coin cell holder, a 3mm LED (any colour should be fine), a PCB-mount switch, and a resistor. A complete parts list for both projects is available as a link below if you want to find where to source some of these components. The value of the resistor is usually around 68 ohm for most colour LEDs. It is a surface mount device, so is very small - the exact type you get isn't critical - I used a "1206" package as it is easier to solder, but 0805 or 0603 packages can be soldered on as well if you have good eyesight! If you are using a blue or white LED, they are meant to be too high-voltage to really use with a single coin cell, but if you use a bright one, you can just remove the resistor completely (short with a blob of solder or use a "0 ohm resistor") and the light, although not full intensity, should be quite bright (see the image of it turned on a couple of pages later). You want to get the highest intensity 3mm LED you can find - there are some great deals on ebay, which is usually the cheapest place to find these.

If you want more information on how both of these projects work technically, including how to properly choose resistor values, see the extra technical information sheet that I have posted below as well. I could make up a batch of 100 of these for under $1 each, including PCB -not bad for some extreme marketing, but you could probably even half this price if you were serious about making these in quantity and could do without the battery holder (see the notes in the parts list about welding batteries).

Step 3: Soldering Time

I'm afraid a complete tutorial on soldering isn't within the scope of this instructable either, but the torch is quite easy to solder. I put a blob of solder on the iron, and then whilst holding one end of the component down with my finger or some tweezers, I apply this blob to one end of the component. Then I solder the other end, and finally go back to the first end and solder it again. All components can be put either way around except for the LED - for this one the longer lead is the positive (check before you shorten it!), and should be at the bottom of the PCB in this image (next to the resistor). The negative end can also usually be told by looking for a flat mark on one side of the LED's plastic cover.

Step 4: Does It Work?

Insert the battery with the positive side up, and press the button, and you should have a functioning key ring light! As I mentioned, this design is an experimental prototype only - if I produced these on mass, I would probably change a few things. Firstly, I would make the board smaller still (for cost), and put the name/contact details on the reverse of the board. I might also change the CR2032 cell to a CR2016 as this is thinner, and cut a hole in the board to mount it inline. This would make the whole thing very thin indeed. I might even encapsulate the board in clear heat shrink tubing or the like, to stop it shorting out on keys whilst in the pocket.

Do you think that you can handle an even more advanced design? If so, read on to see how the "autodialing card" works ...

Step 5: The Autodialling Business Card!

I'm not going to try to convince you that this is a particularly useful invention. It is an unashamed novelty - one that is designed as a show-off piece for giving to my better leads. The idea is that it actually dials me up by sending the series of audio tones (Called "DTMF") that the phone system uses to dial numbers. You pick up a phone, hold the corner of the card to the mouthpiece, and tap it, and the card emits these tones, and dials my number. Think of a musical greeting card on steroids - you can program it to dial any number, and it could easily be modified to play a tune or even speak a message given a little hardware modification and some more memory. I could make a batch of these for around $2.00 each - a similar price to some of those flash etched stainless steel cards, but a lot more inventive! The proto was a little more expensive, due mainly to the price of some solderable lithium cells (more about this later). Like the torch business card, it is not meant to be given out in the hundreds - I have a standard "boring" business card for those who just need my contact details and others for those I am really trying to impress!

This is all possible because of miniature programmable microcontrollers - they are now so small and so cheap, they can be put into disposable items. The one I use is made by "Microchip", and costs 39 cents in quantity (and not much more in singles). It can run any small program that you write, and can run it at 4 million instructions per second. I can safely claim (for the moment), that I have the world's most sophisticated business card! You could easily program the microcontroller to do any number of things that fit within the program memory instead - perhaps a simple version of the "business card torch" described earlier that has a flashing light or even "S.O.S." function. Your imagination is the limit here.

A bit of a warning first, though - this is well and truly in the class of an experimental device - it needs considerable tweaking to get working on an individual phone system, and doesn't work on mobiles. It may also not work on some PABX (business phone) systems, depending on the brand. I have quite a bit of experience in electronics, and some good test equipment at my disposal, and this design isn't really setup to be able to use reliably on all phones, so only "extreme experimenters" and those willing to improve the technical aspects of this design should attempt construction - this is definitely not a beginners project, but as mentioned, it might inspire some other designs, rather than being ultimately a really useful one by itself.

Step 6: Parts for the Dialler

Here you can see the main parts. As before, a detailed parts list for both projects can be seen below if you are mad enough to actually want to build it. The items on the left are blank PVC ID cards - available very cheaply. These can be used to enclose all sorts of other electronic gadgets (more about that later). The batteries are in the middle - I used two PCB-mount CR2016 batteries, as these are very thin (1/32" or 1.6mm). The PCB is next to these (see below for an EPS file, and a 300dpi bitmapped version if you can't read an EPS), and on the right is a piezo disk which is used to create the tones, and also as a "switch" to detect the tapping. On the bottom is one of the microcontrollers (actually, shown here is a strip that contained five of them) - it is a PIC 10F200.

If you click on the second picture, you can see some miscellaneous equipment that you will need - some printable OHP transparencies, some spray glue, some PVC solvent cement (used for joining PVC pipes), a device for programming the chip, and on the far left, 5 pins cut off a strip of 0.1" pin headers, to connect the programmer to the board. The PIC programmer itself is ridiculously cheap for what it is ($35.00), and can be used for countless other projects as well - Many thanks to Microchip for making such a great development tool available at such a cheap price. The bottle next to the PVC cement is just to make application of the glue easier - if you do use your own bottle, make sure it isn't made out of a plastic that is dissolved by the cement!

Step 7: Electronic Construction

Assembling the electronic components is not hard, but needs a steady hand, and some experience with soldering. Solder the components as per the image. The two batteries straddle the PCB and are opposite ways around - the one on the left should have its positive side up. You can't see from this image, but you also need to solder a piece of wire between the two battery contacts on the opposite side of the board as well. The PIC is soldered to the PCB on the supplied pads - pin 1 is on the bottom left - if you have very good eyesight, the writing should be the correct way up when you are soldering this item as shown in the image. I find the technique of tacking one pad down with solder first to hold it, and then soldering the other pads, works well. The piezo is soldered to the two pads closest to the chip. I have reduced the length of the wires so that the whole assembly fits within the space of a single blank PVC card.

Step 8: Programming the Card

The next step is to put the dialling program into the chip. If you have bought the PIC Kit 2 programmer, it has everything you need with it, but you should download the latest version of the programming software from here, as some versions of the software don't support the PIC10F chips. Download the code as well from the bottom of this page, unzip it and put it in a directory somewhere on your computer - then from within MPLAB, go to the "Project" menu, select "Open", and navigate to the "BCard" file. Change the stored number (around line 90 in the code) to your phone number rather than mine(!) - it can be a longer number, but after the last digit of your number, the following line should read:

retlw h'ff'

Go to the "Project" menu again, and select "Build All" - check there are no errors, and you are then ready to program. I use a simple technique of inserting a broken-off strip of 5 pins from a strip of 0.1" header pins into the programmer, and then just touching the 5 pins (see the picture) whilst programming. This is a little fiddly, but as the erase or program cycle only takes a second or so, it is quite manageable. If you are experimenting, it is well worth soldering the strip of 5 pins onto the board until you have finished your changes. When you are ready to program, select the "Erase" and then "Program" options from the "Programmer" menu. If all works OK, you should be able to remove the programmer, and tap the piezo to hear your phone number being dialled!

Step 9: Creating the Graphic

Time to make it pretty! First use a graphics package to design your business card. I used a background image to make mine look a little different, and then had the writing in white. The design should be 1/8" larger on all edges (3mm) to allow for a "bleed". Reverse the image in your graphics package if possible (or otherwise at print time within your printer driver), and then print onto a transparency. Turn the transparency back over the right way, and you will have a nice design protected by the thickness of the transparency plastic. To see more detail of this technique, check out my "Professional Looking Gadgets" instructable - you may even notice a similarity in background images!

Note that I made a conscious decision to omit my phone number from the card to force someone to try it out. It may be a wiser decision to list the number on the card as well in case of problems getting it to work!

Step 10: Sticking It On

Turn the transparency back so that the ink is up (should be reversed writing), spray on a light covering of glue, and stick on one of the blank ID cards. Then trim neatly around the image with a sharp knife or scalpel. Click on the second image to see what it looks like so far!

Step 11: Encapsulating It

This step shows you how to make enclosures for electronic gadgets using PVC cards - using solvent cement to glue them together - this could be a separate instructable just by itself. I have now used this technique for other things like a credit card torch, which was wired using stick-on copper tape (perfect project for kids), and even a bugging device. They look professional, even without a graphic overlay, are easy to build, and super cheap as well. You can make them any thickness using multiple spacer cards between the front and back. For this project we need two spacer cards as they are around 1/32" (0.8mm) each. For thicker projects you can cut strips of "PVC foam" and use this as a spacer instead.

Place the circuit board on the card, and draw around with an OHP marker or similar. Then cut out the inside with a pair of small, sharp scissors. Doesn't really matter if you make a cut in from the side, as this will be hidden anyway, but if you are a little retentive like me, you can drill a hole in the middle first, and then cut out the inside without making a cut to the edge. The dotted line shows where you need to cut slightly inside the line to form a lip where you can glue the piezo disk.

Step 12: Encapsulating It Vol II

The second spacer is almost identical, but doesn't have a cut-out for the wires, and the cut-out for the piezo disk is oversized, with a channel to the corner - this is where the sound comes out!

Step 13: Encapsulating It Vol III

Turn the card that you have stuck the overlay onto upside down, with the arrow pointing to the bottom right, then stick on the first spacer card with the PVC cement. Put the circuit board in the hole now (use a dab of glue if you wish), and then glue (neatly!) the edge of the piezo disk onto the circular lip. I used some more PVC cement, but would probably be best to use superglue or Epoxy - this item should be held tightly. Then glue the second spacer over the top of the first with some more cement (yours should now look like the picture), and finally glue a blank PVC card to the back.

The overall card thickness is governed by the batteries (1/16" or 1.6mm) - I have added another two PVC cards to the front and back, but you could make these even thinner so that the whole card is approaching this thickness of just the batteries.

Step 14: All Done!

Time to test out! Pick up a phone, wait for the dial tone, and put the corner of the card on the microphone. Tap it once and your number should be dialled.

Click here to see a video of the card in action - I'm afraid it isn't the world's most exciting video, but at least it will show you the card in operation. The dialling tones are very quiet, so you might need to turn your volume up to be able to hear it.

I did warn you that this took a little skill to make, and that it was very experimental - I get around a 50% success rate maximum at the moment when dialling on my home phone only by considerable tweaking of the mounting arrangements, and getting the number recognised accurately is highly dependent on a number of factors including your exchange and the mounting of the piezo disk, including the shape of the cavity cut inside the card. I may work on some improvements to this design, as it could get recognition close to 100% (have managed to do this now using the computer to drive the card as a simulator - for those who are very technically minded, I could redesign the card to drive the piezo with a pseudo sine wave rather than a square wave using filtered PWM signals, and increase the tone and space times as well.), although I probably won't bother doing this unless anyone was interested in getting these sort of cards produced in bulk, (which I doubt!). If you are still interested in how the design works, and are a bit of a techno-nerd like me, then check out the technical notes below to look at how this whole thing works.

In case you were wondering, this doesn't work from a mobile phone, as you need a dial tone from the exchange for it to recognise the DTMF tones generated, but as I mentioned, this is more of a novelty marketing exercise than a universal way to dial a number- certainly, it shouldn't be attempted unless you are really up for the challenge of improving the design. It is hopefully also a neat tutorial into some other useful techniques like designing enclosures for miniature electronic devices using ID cards and getting nice graphic overlays done. Finally, hopefully it will also inspire some ideas for other electronic business cards - certainly some of the ideas that people have emailed me privately since posting this have been fantastic, so I know this at least is happening! Time for you to now start designing your own version of the world's most technically advanced business card!


pmanavado made it!(author)2015-04-05

amazing idea you should patent it thank you

rholzmann made it!(author)2011-10-22

hi you have the beginning of the idea , billions of business card are printed on paper each year but something is missing here to make it a world wide market but please free to contact me ( I am living in France ) I just has a wondurfull idea but I am not into electronics ( but I do have tech knowledge as a end user)
+336 25 21 21 21 send me a sms and will return you a valid email

TheWaddleWaaddle made it!(author)2011-06-11

Make: posted a video about a year ago of how you can make your own custom PCB's using the photographic method


laxap made it!(author)2011-06-09

The Autodialling Business Card is just an insanely cool idea!!!

Thanks for sharing.

qorlis made it!(author)2008-09-04

If the chip can be programmed to say something like "I am diabetic" with brief first aid instructions or an emergency number either spoken or programmed to dial, I could see this as a great emergency aid.

TwistedmindZ made it!(author)2009-11-01

i think the problem is that pic chips have a couple of kilobytes of memory if that. so generating more complex sounds would use a lot more memory, might have to have it external or something.

JOBGG made it!(author)2011-03-27

Aren't there those cards where you can save a message and when you open them it plays the message? They aren't that expensive, and you could have the whole thing independent from the PIC itself.

eight made it!(author)2008-09-04

Actually, as a single guy who dates a lot, this would have other uses ! :) Hey... Marvellous instructable. Thanks !!

Nemesis09x made it!(author)2011-03-24

Truly and utterly baffled by the ingenuity of your design.
In one word, fascinating.

dombeef made it!(author)2010-09-12

You should do a site like cardnetics! You have great ideas!

gamermod made it!(author)2009-09-03

im thinkin for a cheap way to do that thing wid a usb in it is to buy 64mb flash drives in bulk put ur info on it then crack the case and put it on the card if u wanna or just get them custom engraved for a bit more

dombeef made it!(author)2010-09-12

They arn't thin enough
And i dont think that they make 64 mb anymore

MichaelMatirko made it!(author)2010-08-16

What about using a reed switch so when you put the card near the magnet in the phone receiver it dials (semi-)automatically?

halmars made it!(author)2010-04-25

Great 'ible., but I think someone will write an "app" they can: email, bluetooth or otherwise transmit to a smart mobile.

raykholo made it!(author)2010-05-23

 well how about a credit card form factor usb key, such that the recipient can plug it into their computer?  A mobile app would pop up that allows the user to send an email to a predefined address, and connect a voip call over pc?

bagshotrow made it!(author)2010-04-24

This is great, because if I was a potential client, I'd be tempted to call you just to see it work. :o  I imagine you sometimes get callers who introduce themselves as "That is AWESOME"

JohnJY made it!(author)2010-03-09

 I've subscribed to you. Your awesome!  

darkdavid37 made it!(author)2010-01-13
your IQ must be 250
Tayl90mm made it!(author)2010-01-28

I enjoy this comment thoroughly. 

imakethings made it!(author)2009-10-05

does this actually dial numbers??

Cubie2 made it!(author)2009-09-11

Ha! thats awesome. Just make one for everyone you know, file them and you never have to look up a phone number again!!!

raykholo made it!(author)2009-08-21

for the dialer try to use a transistor to amplify the signal from the microcontroller and use a single 3v cell... i would recommend a 2N3904 as it is so common; connect the base to where the piezo + used to be, the emitter to the piezo +, and the collector to the + of the battery. i didnt see a schematic so it might be the other way around, but this should work.

tomward made it!(author)2009-08-21

It's not really the current that's needed but the voltage ands we are already feeding in close to the maximum voltage we have - piezos draw almost no current, so the only way to increase the audio output is to increase the voltage - either by using another cell or by a step-up circuit.

raykholo made it!(author)2009-08-22

in my understanding, a transistor here will amplify the voltage however, if not, then a simple smt inductor should also work. original design was pretty clever about this stuff though

tomward made it!(author)2009-08-22

A transistor can only amplify a voltage up to the level of the power supply. Here we are essentially feeding the piezo with a 3V (or 6V with two cells) square wave already. Didn't go for the inductor idea as it was hard to keep a thin card with an inductor-based step-up supply and it was simpler and cheaper just to add another cell. Certainly if you were able to do this however, the piezo would be much louder and more able to put out a decent DTMF signal - piezos can often be driven with up to 50V or more to increase the volume.

raykholo made it!(author)2009-08-22

well that is true. Your way works great, no complaints there. Nice work

captain+Jack made it!(author)2009-03-16

very clever

Rimwulf made it!(author)2009-04-24

Three words "Rejection Hot line"

crazzzik made it!(author)2009-07-02


sharlston made it!(author)2009-05-19

you need to patet it so no one copies

elyena made it!(author)2009-05-10

This is so badass. Thank you so much for doing a tutorial, it's really neat!

andros1200 made it!(author)2008-12-22

On the card: If you have any problems press here. *sets the number to 911*

jeff-o made it!(author)2008-08-29

Perhaps a small hole on the back of the card, aligned with the hole on the piezo disc, would permit better conduction of sound from the card.

Archive555 made it!(author)2008-08-30

But it wouldn't look nearly as cool, now would it?

jeff-o made it!(author)2008-08-31

Well, you can't really see the hole in the corner, which I suppose is the point. But, you do want it to work as well!

Archive555 made it!(author)2008-08-31

But there must be some way to make it work better, yet still look as cool.... Hmmmmm.... I wonder.... I've got it! Turn it into a robot flying death-ray UFO machine, and put the speaker in its mouth! Perfect!

jeff-o made it!(author)2008-08-31

Hmmm, I think the goal of this project is to win clients, not annihilate them from the face of the Earth.

blueninja33 made it!(author)2008-09-13

But what if you could do BOTH!!??!!??

Archive555 made it!(author)2008-10-25

I like your thinking! What if the speaker instead said things like "BUY MY PRODUCTS OR BE ANNIHILATED!". And if they didn't comply, - BOOM! Destruction! Lasers! Cool sound effects! Hmm...

andros1200 made it!(author)2008-12-22

Now that would be one business card I couldn't help but take from the little dispenser thingy.

gannon12raiders made it!(author)2008-10-14


Jeebiss made it!(author)2008-08-31

I made one of these, and use a really fine, plastic screen over the ring, which concealed it, and still let through the sound.

srhadaham made it!(author)2008-10-14

thats a lot of work for a business card

tankboyben made it!(author)2008-01-08

insane and absolutly amazing =oO. would love to have a go at that but i wouldnt have the 1st idea when it came to programing it, would like to have seen some back and side pics. top job dude

tomward made it!(author)2008-01-08

Yeah - must take a side pic - it really just looks like a strip of white that is 3.2mm thick. Back I didn't put on because it is just plain white!

c2p made it!(author)2008-10-03

Hi Tom, The company I work for could make these easily. In fact I would be interested in helping you design the least expensive and thinnest card. I am thinking of making a bunch for the CES show in Vegas as a give-away. We would injection mold these. Of course I would give you all the glory. Smart design!

tomward made it!(author)2008-10-04

Go for it, but don't underestimate the amount of work this design still needs if you really want to make it work properly as stated in the article - getting accurate DTMF recognition from an audio system just a couple of millimeters in thickness is not trivial, and will require quite a bit more development work. Good luck, though and look forward to seeing what you come up with!

c2p made it!(author)2008-10-03

by-the-way contact me at:

theXmaker made it!(author)2008-09-13

are you going to sell that??? if so, please tell me its price

tomward made it!(author)2008-09-14

As mentioned in the instructables, the design needs some improvements I think before sold commercially, and unless a company was interested in ordering a large amount of these, it would be hard to justify the extra development expense - this one is more of a proof of concept.

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