Everything for Electronics


Build a Freezer Alarm Circuit

I’m not sure if it’s absent mindedness or just old age, but sometimes I’ll forget to close the food freezer lid after shopping for groceries. With food prices seemingly going up every three days, there’s really no good time to lose a pile of food because of a simple mistake. This article describes my solution to the freezer problem.

Build the FLiPVox Laser Theremin

In my previous Theremin article, I described the first of my laser Theremin projects: the LASERVox. This is a simple-to-construct Theremin-like device that acts as a MIDI controller for a synthesizer. In that article, I discussed the possibility of a more analog style laser Theremin that has its own built-in synthesizer or pitch generator. That’s the topic of this article! We’ll build the FLiPVox: a continuous pitch laser Theremin with its own mini synthesizer.

Pinochle — Social Distance Style

I belong to a group who enthusiastically plays Pinochle once a week. Unfortunately, with the present circumstance of social distancing during the COVID-19 pandemic, we have been deprived of our weekly get together. So, with today’s technology and an introduction to the virtual conferencing provided by Zoom, I decided to see if we could play Pinochle online.

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 Super-Secret Invisible Burglar Alarm

One educational trend in the US and globally is an increased emphasis on Science, Technology, Engineering, and Mathematics. STEM education aims to expose children and young adults to the world of technology with the hope they will become the next generation of much needed scientists, engineers, and mathematicians. As with all educational initiatives, the success rates are greatly amplified with the addition of an at-home educational component. As a reader of this magazine, you are likely qualified to take on this role, helping expose youth to the many exciting aspects of STEM. This project gives one example of how you might contribute.

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.