Screaming Circuits: Electronic Business Card Holder, Part III

PROTOTYPE AND SMALL VOLUME
PCB ASSEMBLY MADE EASY

Electronic Business Card Holder, Part III

If you haven't yet read part one or two of this series, find them here:

With all of the key design decisions under my belt, it was time to build. I ordered the boards and parts myself, then hopped onto our website quote engine and placed a kitted order. At the time, I hadn't had anything built for a while, so it kind of freaked people out to get an order from within the company. When I do this, I like to go through our web system, just like any other customer, which sometimes causes a bit of a "we traced the call, and it's coming from inside your house..." moment.

20160324_103054Anyway, we didn't have any problems with the build. Fortunately, I took my own advice and carefully labeled the LED polarity. LED polarity marking "standards" are so unstandard, that extra caution is always a good thing. Anything to reduce ambiguity is welcome.

My calculations suggested that I should get six to nine months of battery life with a few cards being pulled per day. After running the blue LED version for about three months, I was satisfied that battery life would be sufficient. That was good timing, because at about the same time, I was down to about two weeks before the show that I was planning for (one of the Embedded Systems Conferences).

Again, I sent an order through our website. This time a full turn-key, using PC boards from Sunstone. And, this time, no one was 20160324_101515surprised by seeing an in house order. I ended up with plenty of time to program the boards before the show, and was ready to give them away for our in-booth contest.

Since that time, I've left a blue/red card holder and a green/red card holder on my desk with the original batteries. After about a year and a half, the battery voltage dropped enough that the blue LEDs no longer show. The red and green, with a lower forward voltage, are still going strong.

Here are the final specs:

  • 1.5" x 3.5"
  • Two CR2032 coin cell batteries
  • Has a Microchip in circuit (ICSP) programming port
  • Has an I2C/SPI port
  • Microchip PIC18F46k22 microcontroller
  • Freescale MMA8452 3 axis accelerometer
  • Recommended capacity, 10 cards

Next time, I tell you what you need to do to get one of these limited edition Screaming Circuits electronic business card holders.

Duane Benson
A farmer is someone out standing in his field

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