Business-card is a transistor amp

From Make's Matt Mets: "Aaron Alai designed this kicking electronic business card, which demonstrates how transistor amplifiers work. When you touch two electrodes on it, a small amount of current is conducted through your body, which is then amplified by a transistor to light an LED. I like the clean design, which is both functional and descriptive of how it works."

Aaron calls it a "small interactive exhibit" in business-card form. I've always had a passion for great cards -- this one is a cake-taker. I stand in awe.

Business Card / Transistor Amplification (Thanks, Eric!)


  1. I just wonder what his cost per card is. . .I mean, as a mere mortal, I tried to get the nice cards with the raised rubberized letters and was told “Too much. Here’s a box of Avery Index Cards and you can use the laser printer.”

  2. Simple? Each card takes an hour to make. Awesome for sure, and a great distraction from the pain of job-hunting.

    Also, I can just imagine chatting with this guy and asking for a card afterwards, and then being totally disoriented and confused when he’d inevitably say “sorry, no.”

  3. Wow! I check this site all the time and didn’t expect to see my business card up here. I have received a lot of emails asking for more instructions on how to dye the substrate. I just cut out a bunch of blanks and when I get around to dipping them in acid (finding a job is almost as much work as having an actual job) I’ll document the coloring process. It will also be an excuse to try other colors.

  4. So I am still not understanding how a transister is amplifying something here.
    You complete the circuit with your fingers and the light lights.
    What did I learn? or am I missing the lesson.

  5. wow, love the organized desk in the background. Looks like he used those tinkertoy things and got a bunch of empty bottles with labels. Nice idea. might try something like that.

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