Nuts and Volts - July/August 2018

24 Build a MIDI Lyre

When you think of MIDI controllers, you probably think of a keyboard. However, there are many reasons to have MIDI controllers in other form factors, not the least of which is fun! In this article, we will make a MIDI lyre version.

■ By Jim Arlow

34 Build Your Own Funky Steampunk Display

I use LCD displays in almost every project.

However, in this modern age of steampunk, I stumbled on something much cooler. I found these 1” high seven-segment electromechanical displays (EMDs) that go clickity, click. I embarked on an ambitious project that featured five 1941 vintage rotary phone step-by-step (SXS) switches. I thought these EMDs would be the perfect match to display the dialed digits. So, I ordered a dozen and the rest is history.

■ By David Goodsell

42 Build a USB Cable Continuity Test Jig

If you’re like me, you likely have a drawer or shoebox stuffed with assorted USB cables that are used to either charge or program a USB device. The problem often is that some cables may only be useful for charging, and which only have the +Vcc and ground wires intact with one or both data wires either broken or not connected in the first place. Here’s a simple test jig to help you tell what’s what.

■ By Don Dorward VA3DDN

44 Does Inductor Winding Have You Tied Up in Knots?

While resistors and capacitors are easily procured and stocked, most radio frequency circuits require inductors in a wide range of very specific values. In most cases, you need to create these yourself, by winding wire on ferrite rods or toroids of specific types and sizes. Is it possible to substitute another ferrite piece at hand and still get the right inductance value? How can a hobbyist measure inductance without buying an expensive instrument? This article describes the principle behind inductance and presents some tricks that I’ve used to make my own inductors.

■ By Dev Gualtieri

49 VINTAGE COMPUTING:

Amigo Color BASIC — The Missing Manual

The original documentation for the Amigo retro computer was intended to help readers mentor youngsters on computer programming fundamentals. It also included an “overview of most Color BASIC commands.” A couple of astute readers working beyond introductory mentoring have asked me about the full command set. This article covers those “missing” commands, plus a couple of tips and tricks that Amigo owners may find helpful.

■ By Dane Weston

58 A Digital Analog – Part 5

This final article in our series will examine those circuits from the “555 Timer IC Circuits” by Forrest Mims which were not covered in any of the preceding four articles. As in the other installments, some will use the PIC replacement from the first part, while others will develop specific programs using a PIC to emulate a particular implementation of a 555.

■ By Larry Cicchinelli

66 Get ASCII Data from PS- 2

Keyboards

You can buy inexpensive PS- 2 keyboards, but they don't produce ASCII values many applications need. To further complicate things, these keyboards have their own code-transmission protocol. I'll show you how to use a system-on-a-chip and a bit of software to convert PS- 2 key codes to corresponding ASCII values.