Variable Speed Fan With Snap Circuits, Kano Computer

In a previous How-To Guide I demonstrated how to blink a Snap Circuits LED with the Kano Computer...

IUPUI researchers use stem cells to identify cellular processes related to glaucoma

INDIANAPOLIS -- Using stem cells derived from human skin cells, researchers led by Jason Meyer...

Pi Day 2016 Project

For Pi Day 2016, I’ll demonstrate how to flash a Snap Circuits LED with the Kano Computer (my...

LIGO, Gravitational Waves, And Laser Interferometry

UPDATE: LIGO has detected gravitational waves. ...

Excerpt from “The Terrorism Delusion” by Meuller and Stewart:

We have argued that terrorism is a limited problem with limited consequences and that the reaction to it has been excessive, and even delusional. Some degree of effort to deal with the terrorism hazard is, however, certainly appropriate—and is decidedly not delusional. The issue then is a quantitative one: At what point does a reaction to a threat that is real become excessive or even delusional?

The diode has a number of applications in electronic circuits. One application you may be familiar with is a rectifier. A rectifier converts alternating current (AC) to direct current (DC). Alternating current periodically changes direction while direct current only flows in one direction. "The most common function of a diode," according to Wikipedia, "is to allow an electric current to pass in one direction (called the diode's forward direction), while blocking current in the opposite direction (the reverse direction)." It’s easy to demonstrate how the diode will let current flow in one direction but block the flow of current in the opposite direction.

Parts needed:

What’s a relay? You’ve probably seen a relay race where one runner hands off a baton to another runner. Similarly, an electronic relay hands off control from one circuit to another. A relay is a very simple device consisting of an electromagnet, an armature (a switch that closes when attracted by the electromagnet), and a spring that is connected to the armature.

(Diagram inspired by:

In my previous article about the Kano Computer, I demonstrated how to use MIT’s Scratch graphical programming language on the Kano to flash an LED (the “Hello World!” program of hardware hacking). In this article, I’ll again demonstrate how to flash an LED, but using a special variable in Scratch called “MotorA”. Scratch automatically handles all of the programming for MotorA to produce a “pulse width modulation” (PWM) signal on Pin 11 of the Raspberry Pi. For a primer on pulse width modulation, see this article.

"In space no one can hear you scream" was the tagline for the movie Alien. I finally created a Twitter account, but in Twitter, if you have no followers, no one can read your tweets. You are welcome to follow me on Twitter: @SteveSchuler20

Picture source.


My colleague, Tony Troxell, has a blog called Geeking in Indiana with the tagline, “Movies, Tidbits, and General Geekery from Around Indiana.” Tony explains the purpose of his blog here.