Nuts and Volts - May/June 2018

Departments

06 DEVELOPING

PERSPECTIVES

The Boiling Frog

08 READER FEEDBACK

24 NEW PRODUCTS

25 SHOWCASE

92 TECH FORUM 95 CLASSIFIEDS 95 ELECTRO-NET 95 AD INDEX

96 NV WEBSTORE

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Projects & Features

28 Build an Analog-Style LED Clock — Part 2

Last time, we looked at a test circuit that had 12 LEDs. Using Charlieplexing, we ran those LEDs with only four I/O lines and determined that expanding the LED matrix to 14 I/O lines would enable us to individually control 182 LEDs. We also looked at how to incorporate the reading of four pushbuttons by connecting them to the LED matrix with a handful of other discrete components. This time, we’ll expand the LED matrix to run the 182 LEDs that the clock uses and make a printed circuit board (PCB) for the clock. Then, we’ll wrap it up with a discussion of how the software works and put the finishing touches on our unique timepiece.

58 Setting Up the Raspberry Pi 3
Tired of canvasing the Internet trying to find clear and
comprehensive information on how to use the Raspberry
Pi 3? Well, this is the tutorial for you! We’re going to build
a simple camera stick with the Pi camera which snaps a
picture when a button is pushed. This is akin to a “Hello,
World!” initiation for using a camera module with the
Raspberry Pi. It teaches you how to set up the Pi, install a
camera, use a couple General Purpose I/O (GPIO) pins,
and a smidgen of Python programming.
■ By Morgan Chen and Robert L. Read

■ By Robert Gill

36 Build a Continuity Tester

During a recent vacation, I challenged myself to come up with a design for a continuity tester that suits my particular testing requirements. Most of the time, I go straight for a microcontroller, but this time I decided to use only non-programmable components. I also decided to use only through hole components to make soldering easier.

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■ By Douglas Booth

40 Build the Musical Laser Rainbow Machine

I’ve been searching for a way to give our band’s performances the kind of visual elements that can only otherwise be achieved by true lighting artists. As a musician, inventor, and laser enthusiast, I decided to draw on all my hobbies and try to make something myself. By programming software and combining lasers, stained glass, and motors, I have created a light machine that has unique responses to each tone, frequency, and beat. This unit can enhance the listening experience for live shows or recordings of your favorite music.

■ By Victory Chaney

52 Understanding Ohm’s Law with a “Trick” Question

For many years, I have enjoyed learning about various aspects of our universe such as electricity, computer systems, and physics. I have met engineers who “just got it” when it came to Ohm’s Law and others who struggled due to incorrect preconceptions. Just because we can “work the math” does not mean that we really understand Ohm’s Law well enough to make it work for us. This article will help you gain a real usable understanding of Ohm's Law.

■ By John Pawlicki K8AG

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