Tie And Jeans

Under the Hood

Laura is a smart cookie.  The voltage frustration that emerged from the intersection of batteries and LED series is entirely a matter of exposure.

The problems she details in this thread exist at a level of electrical detail that she’s never needed across years of learning to code, teaching CS, diving into and teaching physical computing, coaching a whole variety of robotics teams, and renovating a house! Big tools or appliances might draw to much current and blow a fuse. Robotics are designed for and often ship with specific batteries and polarized plugs. All designed, commercial systems are careful abstractions that do their best to constrain the users exposure to the confounding detail and complexity. Smart engineers have gone to incredible efforts to make the user experience feel closer to redstone than 6.002.

A major contributor to this layer of abstraction is the cheap, accessible ubiquity of micro-controllers and other discrete logic systems. This creates unified circuits that use electricity as bounded signals. In these circuits, failure occurs when signals are blocked or interrupted, but rarely every as a result of signals that fall outside a component’s expected/acceptable range.

The heart of Laura’s LED problem was a circuit that could be closed and complete, but still not function. It’s not that this is complicated, but that behavior is orthogonal to the “blink sketch” mindset.

So that’s it, right? Here’s the great example of why #makered novices need some “real” electronics knowledge.

I’m still skeptical. Clearly, there’s a good lesson lurking in here that could be packaged up neatly into a bag with LEDs of various Forward Voltages and a small pile of batteries. Blow a single LED with a 9v (actually a step in the great Make: Electronics book), have a 3v coin cell power two small red LEDs but fail with two blue ones, compare series vs parallel circuits with copper tape. I think that’s probably enough hands on experience to convince a novice to check Adafruit’s Circuit Playground app when a LED circuit doesn’t behave as expected.

My skepticism about the value of “real” electronics knowledge for novices in 2014 comes from how complex the picture becomes when we look under the hood of digital logic assumptions.

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One thought on “Under the Hood

  1. Pingback: On not knowing | Geeky Mom

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