One hobby that’s prevalent today is restoring antique radios. Once you have an antique radio, it’s nice to listen to it. Unfortunately, the content of present day AM radio stations leaves a lot to be desired. There’s nothing comparable to the type of programming that was on the air in the heyday of radio broadcasting. The solution to this dilemma is to use a low power crystal-controlled AM transmitter to broadcast age-appropriate material to the antique radio. Such an AM transmitter is the subject of this article.
If you care about the weather and enjoy creating graphs that give all kinds of details, then you’ll really enjoy this sequel to the original graphing thermometer presented in Issue-2 2019. Features include outdoor and indoor temperature, outdoor and indoor humidity, wind speed, wind direction, rainfall, and barometric pressure.
Wouldn’t it be handy if you remembered to bring everything you need when you leave home without having to remember to remind yourself to remember? Well, the MEMO_BOX is just what you need! It will alert you with custom messages with its motion detector when you pass by it when you leave your house. Plus, you can use the motion detector to do other things like set off a recording of spooky sounds to delight trick-or-treaters when they come to your front door.
Many of us have fond memories of assembling sections of track and spending many enjoyable hours racing slot cars, either alone or with friends. Maybe it’s a hobby you’d like to get back to (or never left) or share it with the next generation of slot-car racers in your family. Racing these miniature cars around a track is only part of the fun! With a little amount of expertise in electronics, there are definitely many accessories we can build ourselves — probably enough to fill at least a small book. Since we don’t have that much space here, I’ll highlight only a few of these project ideas.
Magnets are magic! To suspend something in air repelled by a magnetic field is a bit of a trick. We need some electronic control of the situation to stabilize magnetic levitation. See how I achieved this and made a castle float in the air. This project is sure to delight and mystify family and friends!
This project takes you through the build of a compact pocket-sized vacuum cleaner. It’s portable, convenient, and super easy to use. It includes features like powerful suction, reverse mode for a blower, built-in nozzle storage compartment, and line-in mode to power from an external power brick.
Sometimes called a VI curve tracer or an IV curve tracer, this oscilloscope Octopus generates AC excitation across its two leads and then displays a voltage vs. current plot in real time. The resulting plot can be used to track down opens, shorts, and noise in a component, as well as measure the breakdown voltage and phase relationship between voltage and current. The circuit has been around just as long as oscilloscopes, but this Octopus is a small battery-operated instrument with its own display. Instead of an octopus’ worth of jumbled cables, there’s just a pair of test leads.
With all the focus on the coronavirus (or COVID-19), there has been an upsurge in demand for a variety of germ-related products. This science project presents an afternoon build of assembling a UV sanitizer from a UV LED panel and a small reflective enclosure. With STEM students in mind, we’ll look at measuring the efficacy of the sanitizer on bacteria through the use of inexpensive, premade agar plates.
When I was in junior college, I did an experiment in a physics class that I have never forgotten. It was the classic falling body experiment to measure the acceleration of gravity; 9.81 meters/sec2. I loved carefully adjusting the apparatus and meticulously taking the data, trying to get a result that was as close as possible to the established value. Frankly, I don’t recall how close I got but it was the thrill of scientific inquiry that grabbed me. Now, in this age of computer technology, I thought it might be challenging and fun to see how good I could do in my garage with a fairly simple DIY apparatus.
This article discusses basic theory on the decibel unit and its role in electrical measurements of power, etc. It also describes the construction of an RF power meter which in the past has been difficult to use and expensive to own. With the breakthrough of new ICs in recent years, most of the former problems and expense have been eliminated. This is a simple and inexpensive unit to build, but has the accuracy, resolution, and dynamic range that was only obtainable in lab quality test equipment a decade or so ago. This kind of test equipment is almost mandatory for amateurs, radio frequency work, or test equipment calibration. Also, when built as described, it’s a very professional looking piece of gear that anyone would be proud to display on their test bench.