Maker Faire 2024: The Invisible World of Radio Waves

Lake County Maker Faire

Welcome to the project page for Maker Faire Lake County 2024. We have been working very hard to prepare for the Faire. The Faire was well attended and we enjoyed talking with you and hope you enjoyed your visit at our exhibit. After the Faire, we will be updating this page with more information about the projects from the Faire and addressing your questions in greater depth.

 “Get RadioActive” Badges

As Makers, it is all about learning and making. For this year’s Faire, we wanted to remind visitors about our exhibit by creating a keepsake. This is how the idea of the “Get RadioActive” badge came about. Besides creating a colorful “blinky” badge that reminded visitors where to go for more information about amateur radio, it provided an opportunity for us to learn new techniques and to solve some interesting challenges.

The process began with designing the front of the badge. The size of the badge was chosen to be similar in size to the popular “Hello., I’m..” stickers or membership badges for clubs and organizations.  The message would have to be kept simple, provide a way to contact MCWA (McHenry County Wireless Association) for more information, and have a catchy graphic. Originally, the use of a QR code for contact information was considered, but it was decided that there wasn’t enough room to accurately 3D print it without sacrificing the core message or graphic. The photo above shows the final design, which includes a colorful “antenna” graphic with a multi-color LED in the center to depict radio waves being sent out. The badge is a three color design: yellow, black, and red. More on how that was accomplished with the Prusa i3 MKS3+ printer will come later.

The second component was the back of the badge that held a single 3 volt CR2032 battery to power the LED as well as two mounting magnets. The magnets allow the badge to be attached to a metal surface such as a refrigerator or to clothing using a magnet badge clip, which was also designed. Several iterations of the back were built and tested. It was planned to have some type of on/off mechanism to conserve the battery, but ultimately a design that allowed the battery to be slid out from the holder was chosen for cost and assembly time. Another challenge was how to connect the battery to the LED. Paper clips, solid wire, and DuPont connectors (the type of connector pins used when breadboarding projects) were prototyped. The DuPont connector pins gave the most consistent results, but required gluing two of the connectors to each battery holder and then soldering the other end of the wire to the LED. This approach was ruled out due the added effort to glue the connectors to the PLA badges and time it took to strip, tin, and solder two wires to 50 LEDs. The approach that was chosen was to use 3 millimeter wide, 32 gauge flat copper wire used for jewelry craft making (available on Amazon or a craft shop). This turned out to be nearly a perfect choice. The flat wire formed and hugged the top and bottom of the battery compartment and was easy to directly solder the leads from the LED to the wire. It dramatically cut down on the assembly time of the badges, which was important considering the number of badges to construct.

The battery holder was designed using OpenScad as Ralph is a computer programmer and OpenScad felt a more natural choice for him. You could translate that as “I could have used Fusion 360 or even TinkerCad, but time was running out to learn another tool.”

The next challenge was to attach the  8 mm diameter by 3mm high magnets to the back of the battery holder. The first approach was to size the holes such that the magnets could be press fitted into the holder and have a tiny part of the magnetic above the battery holder. A hole diameter of 8.1 mm and 2.5 mm deep was chosen. Initially, that seemed like a viable solution, but two problems were encountered. The first challenge was inserting the magnets firmly into the hole insuring that both magnetic poles faced the same direction. This would become very important when the matching magnetic back clips were made. This problem would remain regardless of the way the magnets were attached to the battery holder. The bigger problem was slight variances in either the hole size or the diameter of the magnets were just great enough to cause one or both of the magnets on some badges to detach after repeated use. It was clear that it would be necessary to glue the magnets to the holder and magnet badge clip. 

There are a number of household adhesives that bond well to the metal magnets and the PLA plastic badge material. The goal was to find the right combination of ease-of-use and working time. First up was CA glue (SuperGlue). It is easy to use and the right glue could be purchased that allowed a reasonable bonding time. The first tests looked promising, but adhesion to some badges was poor, probably due to the porous nature of the filament. Too many of the first run of badges had to be reworked to fix magnetics that wouldn’t adhere properly.

Next up was a two-part epoxy. That DEFINATELY would do the trick. However, the setup and working time required careful attention when gluing up dozens of badges and magnetic clips. It was a time consuming process requiring mixing up small batches of epoxy and gluing a few badges at a time. It was also a smelly process which required adequate ventilation. 

The third  attempt was to use E6000 adhesive popular for crafting and other uses. This glue dries clear, is somewhat flexible (not particularly important for the use here, but a nice characteristic for some projects) and sets within a few minutes with a 24-hour full cure time. This adhesive was used in other 3D printed projects with great results. The adhesive also requires adequate ventilation so a fume extractor was used in addition to working in a well ventilated area.  E6000 comes in a number of different sizes and packaging. The remainder of a 3.7 oz tube was used to glue the battery holders to the back of the badges, while a 2 oz tube with precision tips was used to deposit just the right amount of glue into the holes for the magnets. Both tubes are available from Amazon or a big-box hardware store such as Menard’s or Home Depot. Two tips when using E6000:  1) Keep the cap tightly on the tube when not in use. The glue will begin to thicken when exposed to air. I usually squeeze the tube gently and wipe away a bit of the glue with a paper towel before use and 2) wear Nitrile or other type of protective gloves.  Beside protecting your hands from the chemicals in the glue under normal use, these tubes are prone to split open if too much force is applied and the glue will get all over you and perhaps your project. How do I know this? Don’t ask. Slow and easy is the way to go.

As mentioned earlier, it is important to have the magnets placed so that the poles of both magnets on the battery holder point to the same direction. It doesn’t matter at this point if the North or South pole faces upward, only that both magnets point in the same direction. The easiest way to insert the magnets was to place a small amount of E6000 glue in each of the two holes, and taking a stack of magnets, insert them into the holes making sure not to switch the position of the stack of magnets. You should also slide your thumb or finger of the other hand over the newly inserted magnet and then move the stack of magnetics away from the badge to discourage the newly inserted magnet from jumping back home on the stack. After inserting both magnets, the battery holder was placed on a flat surface to cure overnight with enough spacing between them to make sure that the battery holders didn’t get attracted to nearby ones.

The magnetic clips were assembled in the same manner, BUT with the poles reversed (opposites attract, likes repel). After applying the glue to the magnetic strip, the stack of magnets was brought close to one of the battery holders so the magnets were attracted to each other. Then, moving the stack away from the battery holder, the stack was reversed in my hand so they were repelled by the battery holder. With the polarity confirmed, it was possible to start inserting magnets in the magnet clip knowing that the will be attracted to the badge back.

After curing for about twelve hours, more E6000 was used to attached the battery holder to the back of the badge with the flat wires pointing to the top of badge so the LED can be soldered later. Two daps of E6000 were placed on the holder and then pressed to the back of the badge. Once again, the glued badge assembly was left to cure for at least twelve hours before soldering the LEDs to the wires.

Here is a photo of the glued assembly with the LED press fitted into the badge and soldered into the holder. The positive battery terminal is marked with a “+” sign on the holder. The LED has two leads with the positive lead being slightly longer than the negative lead. If you reverse them, no harm will come to the LED or battery, but the LED won’t light up.

You may be well aware that it is important to have a current limiting resistor between the LED and battery in order to protect the LED from damage. The multi-color LED used in the project has a rating of 20 ma. The CR2032 has an interesting characteristic in that it has an internal resistance of approximately 200 ohms, which allows the LED to be directly connected to the battery without exceeding the LED rating. This was very helpful for the project since it made soldering the LED to the wires much quicker than it would have been if a resistor would have to be added to the circuit. We did experiment by adding a 100 ohm or 180 ohm resistor and it reduced the current flowing through the LED with only a little impact on LED brightness. This will greatly extend the life of the battery, so if you are making one or two of your own badges, adding a resistor may be a worthwhile consideration. 

The first set of completed badges:

Bonus: How to you print multi-color 3D prints if your printer doesn’t have multiple extruders or a special filament swapper?

The Prusa i3 MKS3+ printer used to produce these badges only has a single extruder and no MMU. This means only a single color can be printed under most circumstances. It is possible to print multiple colors with a single extruder, but most solutions limit a single color for each layer, somewhat like rings of a tree. Sometimes this is okay (like the front panel markings of the shortwave receiver case, where a the text rising about the panel was fine), but the goal was to have all three colors to be flat and on the same layer.

The technique that was used here was to print the yellow base of the badge and for the last two layers, add in the other colors. Three STL files were created (one for the yellow base, one for the black text, and a third for the red graphic). In OpenScad, the text and graphic files were subtracted from the yellow base layer to make room on the base for the added files. The final piece was using a special printer profile that created five virtual extruders that was created by Rainer S (the technique and link to the profile can be found here:  Multicolor printing without a MMU. Using Rainer’s profile isn’t necessary to create virtual extruders, but made the whole process seamless for the Prusa.

The tradeoff is that filament changes have to be done manually, which can make the process a little tedious when using many colors and producing a lot of badges. Producing eight badges at a time took just under five hours with the color changing starting at about two hours and thirty minutes into the print. Pay attention to what color filament to insert next when it is time for a color change. One would think it would be a progression (yellow, red, black, yellow, red, black), but the slicer optimizes the changes so there are fewer changes required. The sequence for these badges, which were applied over the final three layers was yellow, red, black, yellow,  red, yellow, black, yellow, and red. Always a good idea to test with a single copy of the model first to avoid disappointment.

Shortwave Receiver Kit

The 40-meter shortwave receiver project that was introduced at last year’s Maker Faire has been updated for better performance and stability. The updated assembly instructions follow.

Download version 1.1 assembly instructions

Download 3D printed case files


Questions from the Maker Faire

Q: I enjoyed seeing what you displayed at the Maker Faire, but is that the main things you can do with amateur radio?

A: Certainly  not.  Amateur radio is rich with areas to explore and enjoy. Many  amateurs were licensed in their youth and still enjoy the hobby fifty or more years later. Besides the exhibits showcased at the Maker Faire, radio amateurs play a key role in public service activities such as storm spotting,  providing communications at events like the Chicago Marathon, and are the first to be called upon in time of disaster.  Amateur radio is an excellent way of learning about other countries by communicating with amateurs in that country. It is also a great way to practice a new language! For competitive gaming types, there is RadioSport where amateurs compete with each other amateurs to score the most points.  And there are opportunities to sit back and have a nice chat with hams in your area or around the country. These are just a few of the many opportunities that an amateur radio license opens for you.  

Q: I heard that amateur radio operators were involved with a scientific experiment during the April 8, 2024 total eclipse. What was that all about?

A: This was an excellent opportunity for radio amateurs to help scientists gain knowledge of radio propagation (how radio waves bounce off our atmosphere) immediately before, during, and after the total eclipse. Amateurs also participated in the total eclipse of August 21,  2017.  While radio propagation may not be the most exciting topic of research, it is extremely important because it determines if radio communications from Point A to Point B are possible or likely to be impacted by solar activity.  Thousands of radio amateurs became citizen scientists by doing what they like to do best: make contacts with other amateurs, providing a rare opportunity for HamSci and the National Science Foundation to gather a rich set of data that will help scientists understand the impact of the sun on the ability to reliably communicate.

Q: Are there any resources that will help me learn more about amateur radio and study for a license?

A: Absolutely! There are many online resources that provide more information about the world of amateur radio and even help prepare you to take your amateur radio examination. There are a number of local amateur radio clubs that not only administer the license exams, but also can help you through the entire process from information gathering, studying for your license, and helping clarify questions that you may have. But that is just the start. Amateurs are eager to share experiences and mentor new hams to help you get the most of out of the hobby. This is an excellent reason to seek out a local amateur radio club near you.

Here is a list of resources to get you started:








Q: Isn’t it difficult to get an amateur radio license? I’m not an electronics wizard.

A: It is true that some studying is involved to become a licensed radio amateur, but the privileges and opportunities a license provides is well worth the effort. You don’t have to be a wizard or PhD. In fact many non-technical people obtain their licenses every day. Even ten year old children (and even younger) have successfully passed the test.  It can be hard, although not impossible, to study and pass the test by yourself. But, you don’t need to go that route. There are many amateur radio clubs in the area that can help you through the process and help you over any rough areas of understanding.

Q: I enjoyed learning about how hams can use satellites that were built and launched for them. How do they get into orbit and how long do they stay there?

A:  Our satellites as well as other CubeSats are typically deployed by the International Space Station (ISS) or sometimes launched as part of a payload from rocket launch vehicle. When the ISS deploys a CubeSat, it can deploy multiple satellites at the same time. The satellites arrive at the ISS as part of a secondary payload on a SpaceX or other launch vehicle. It provides access to space at cost far below that having a rocket directly launch the satellite. CubeSats stay in orbit from anywhere from around a year to as long as twenty five years, depending upon the height of their orbit. The satellites eventually fall back to Earth due to the pull of gravity and burn up in the Earth’s atmosphere.

Q: I found out that the 40-meter shortwave receiver kits were updated with a ten- turn “Tune” control for easier tuning. I picked up one of the kits at the last Maker Faire. Where I can get one of those ten-turn controls?

A: If you need only one or two, Amazon carries them at a reasonable price. Don’t forget to order a knob, if you don’t have one, as the one shipped with the original “Tune” control won’t fit.  Search for “10k ohm potentiometer 10-turn”. Here is one result that is current as of April 2024:  10-turn control

Q: At your exhibit, you mentioned that you were using PiAware, but modified so that you didn’t need another computer to view the display. What changes are needed?

A: First off, it is doubtful that the way you use PiAware to display ADS-B air traffic will require these changes. For the Maker Faire, we wanted to display the map of aircraft on the same Raspberry Pi that was decoding the data so another computer wouldn’t be necessary. Most times, you just need to install the standard PiAware software from FlightAware and have the Raspberry Pi connect to your home network.  Then the map can be displayed by browsing to the the Pi on a laptop, tablet, or phone. 

In the unusual case where you need to replicate what we did at the Maker Faire, reach out to Ralph (WB9ICF) at It will require installing a version of the Raspberry Pi operating system with graphic user interface and manually building and installing dump1090-fa. 

Links to the previous Maker Faire exhibits

2023 – The Mystique of Shortwave Radio

2022 – Morse Code, the “new” old technology

2021 – Amateur Radio in the 21st Century(supplemental materials)