With "smart" cell phones, Wi-Fi, RFID tag systems, and so many other new applications for radio waves these days, it is obvious that we are immersed in an electromagnetic field ("EMF") just about everywhere we go. Here's a circuit to experiment with collecting and measuring the energy present in our environment.
Having read about the ESP8266 NTP clock in previous issues of Nuts & Volts, an idea came to mind to construct an interface camera using the ESP8266. In this project, we used an old Android phone as a camera source and linked to an ESP8266 based webserver. The phone acts as a camera server and the ESP8266 web server acts as a client to the camera server. The webserver displays the live webcam on its web page.
Here are a few of the many possible variations on the general theme of discrete-logic digital clocks. If you have a few LED displays, counters, drivers, and simple logic, you can probably build a clock. Consult the datasheets of the ICs you choose to use, breadboard everything first, and have fun.
Most frequency counters can tolerate only low levels of RF at their input, but here’s a way to safely measure the frequency of an RF signal of up to 200 watts with your existing frequency counter.
I decided to make an electronic musical toy as a Christmas gift for my young son. I browsed the Web looking for inspiration and found the stylophone: a miniature analog stylus-operated keyboard that was invented in 1967 by Brian Jarvis. My unique take on it combines music and writing to make learning fun!
Several months ago, an idea popped into my head for a fun project. I wondered if I could burn some characters into the yellow paint of a No. 2 pencil with one of those powerful diode lasers available on eBay. Perhaps it could be my name or my grandkid’s names, or even a happy birthday message to my lovely wife. Here’s how I did it.
The advent of the ESP32 Wi-Fi development boards allows for an increase in the sophistication of a digital clock. It doesn’t take much imagination to envision a digital clock with a large LCD display to not only show the usual time, date, temperature, and humidity, but to also be able to retrieve things from the Internet like the weather or weather forecast, and stock market reports as well. This seven inch clock also automatically corrects for Daylight Savings Time.
The February and March 2018 editions of Nuts & Volts featured my article detailing the Arduino Graphics Interface (AGI) project which described a general-purpose hardware and software platform that could draw graphical objects onto the face of any analog oscilloscope. A reader challenged me to see if the AGI concept and software library could be ported to the newer and faster TEENSY 3.6 processor. This article describes the new and improved TEENSY Graphics Interface project that implements a fully operational “CRT Clock” as a working demonstration of a TEENSY based graphics platform.
This project is a follow-on from my MIDI lyre project featured in the July-August magazine. I’m going to describe how to build a MIDI autoharp. Like the lyre, this is a MIDI controller, so it doesn’t make any sounds itself. Instead, it sends MIDI messages to an external synthesizer. It’s the synthesizer that makes the sounds.
Over the years with different companies I’ve worked for, I always had access to high-end audio THD (Total Harmonic Distortion) analyzers. I found these very useful for design work, debugging, and repair of audio equipment. My present company has no need for them and consequently they aren’t included in their armory of test equipment. Oftentimes, I have need for one but could never afford to own one — not even a used one. I thought this would be a worthwhile project, so this article describes how to construct one.