Everything for Electronics


An Altair Clone: Then and Now

When I read the article “Build a Pocket-Sized Altair Computer” by David Hunter on building an Altair clone, I was reminded that I too had designed an Altair clone, but I built mine in 1977. Mine required seven boards in a 19” rack. This article details the resources I had then in a comparison of what resources are available today. I’ll also describe how I designed and built my clone.

Can’t Keyboard? Use Morse Code Instead

A few months ago, I accepted a challenge: Design a way for people who can’t easily use a keyboard to create text for applications such as Word, OpenOffice, eBay, or Google via Morse code. It takes only two fingers to create them, and learning to send Morse code proves easier than learning to receive it, which requires much practice. See how I used a $10 Cypress Semiconductor CY8CKIT-059 MCU board to mimic a USB keyboard but without software drivers, code libraries, or special USB-interface ICs.

How You Can Intercept Secret Messages Being Sent to Spies

Believe it or not, there are powerful radio stations all over the world sending out messages to spies every day, and you can hear them with an inexpensive shortwave radio and a simple antenna. You probably won’t be able to decode them, but it’s a real kick to tune in these clandestine signals.

Build the LASERVox MIDI Laser Theremin

The Theremin, invented by Leon Theremin (Lev Termen) in Russia in October 1920, was one of the first electronic musical instruments. It’s also the very first instrument of any type that you play without touching it in any way. An expert Thereminist can play as expressively as a violinist or cellist. If you want an instrument with violin levels of sensitivity, then a regular Theremin is for you. If you want an instrument that’s easier to play and that can control your MIDI synthesizer, then that is precisely what the LASERVox offers. The LASERVox is a perfect project for the novice because it’s a real instrument that can be built very easily with just a handful of components.

Build a Wireless Doorbell Pager for the Deaf

This is a great device for those who need to know when an Amazon package or a friend/relative has arrived at the front door.

FM Reception with the GNU Radio Companion

The complexity and sophistication of the electronic hardware required to recover composite baseband signals in the FM band is beyond the capability of most experimenters. However, modern digital signal processing software, capable PCs, and inexpensive software defined radio (SDR) hardware can now be easily combined to receive the information in these broadcasts. Learn how to combine this hardware, software, and your PC to build SDRs to receive FM radio broadcasts and more.

Build a DIY Electric Scooter

With the influx of electric skateboards and scooters that have taken over seemingly every city, I started thinking it might be something to purchase for myself. Instead, I decided that I would try to build my own from scratch. Not really to save money, but to gain the experience of building something of my own. The primary purpose of this article is to show my design and manufacturing process, so that you can learn from what I built.

Build a DotStar Light Painter

Long exposure photography captures the path of light over time, smearing moving elements to produce a single photo which creates a new realm of artistic photography. However, popular subjects of light exposure photographs are uncontrollable (stars, car headlights, etc.), so we made a light painter using microcontrollers and a DotStar LED strip to develop custom photography from images uploaded by a user.

Build a Potentiometer Box

Now that I’ve retired, I’ve started experimenting with some of the analog subjects that I haven’t done much with since school back in the seventies. To begin with, I started with op-amp circuits; specifically, Colpitts oscillators. I built the circuit on one of those plug-in ‘protoboards,’ a ±15V power supply, an oscilloscope, and a multimeter. For my experimentation, I was using a trim pot. I would adjust until oscillation began, then power down, pull one end of the trim pot, measure the resistance, then re-connect, power up again, and continue adjusting until I reached the other end of the resistance range, where the oscillation would cease. I would then repeat the resistance measurement. That procedure was not ideal. In addition to the multiple tedious steps, adjusting a trim pot can be a pain. Enter my potentiometer box.

Hacking LEDs and Arduinos: Instant LED Projects

Most LED projects involve some wiring, some resistors, a solderless breadboard, and a bunch of jumper wires. Not this one! You can create bright, stunning colors by literally just plugging LEDs directly into the Arduino pins. No wiring, no resistors. Just your Arduino and a handful of LEDs. The is the absolute simplest and lowest cost way to get started manipulating light and color. I’ll show you how to do it safely in this article.