Step 14: All Done!

Picture of 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!
qorlis7 years ago
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.
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.
tankboyben7 years ago
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 (author)  tankboyben7 years ago
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 tomward6 years ago
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 (author)  c2p6 years ago
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 tomward6 years ago
by-the-way contact me at: fkern@c2p-inc.com www.c2p-inc.com
jeff-o7 years ago
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.
alfra7 years ago
so cooooooooooool!
hasiwally7 years ago
Cool Dude!!!!!!!