Everything for Electronics


Circuits for a Day at the Races

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.

Build a Castle in the Clouds

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!

Build a Pocket-Sized Vacuum Cleaner

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.

Build an Oscilloscope Octopus

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.

UV Sanitizer: How to Build One and Measure Its Efficacy

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.

Newton’s Apple

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.

A Discussion on dBs and RF Power Meters

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.

A Semiconductor-Based High Voltage Utility Power Supply

For those who experiment and build with vacuum tubes, an adjustable regulated benchtop high voltage power supply is essential. Many circuits for such units have been described that themselves use tubes. It’s nice to be consistent, but we can save some bench space and a few watts by using semiconductors in such a unit.

Build an Audio Loop System

The last time I had my hearing aids serviced, I discovered that the devices included a T-mode operational feature. The T-mode (or Telecoil) setting allows you to receive audio signals fed to an induction loop, which is just a wire loop laid on the floor around the perimeter of the desired area. Induction loops can be found in places such as concert halls, movie theaters, auditoriums, churches, banks, and public buildings where PA announcements are common. I decided to build an installation for my home. Here’s how it went.

Build a Radio Pet Tracker

Knowing your pet’s location is invaluable. With modern technology, there are commercial solutions giving accurate GPS location for days on end. However, these options are costly. So, as a useful and educational project, I built my own tracker using a simple radio beacon.