We like to pretend that our circuits are as perfect as our schematics. But in truth, PCB traces have unwanted resistance, capacitance, and inductance. On the other hand, that means you can use those traces to build components. For example, it isn’t uncommon to see a very small value current sense resistor be nothing more than a long PC board trace. Using PC layers for decoupling capacitance and creating precise transmission lines are other examples. [IndoorGeek] takes us through his process of creating coils on the PCB using KiCad. To help, he used a Python script that works out the circles, something KiCAD has trouble with.
The idea is simple. A coil of wire has inductance even if it is a flat copper trace on a PCB. In this case, the coils are more for the electromagnetic properties, but the same idea applies if you wanted to build tuned circuits. The project took inspiration from FlexAR, an open-source flexible PCB magnet.
We’ve all heard it a thousand times – they don’t make ’em like they used to. Sometimes, that’s for good reason, but there is a certain build quality to electronics of the mid-20th century that is hard to find in hardware today. This inspires great nostalgia and dedication in some, like [Michael Park], who set out to build a calculator reminiscent of the best HP designs from yesteryear.
The scissor mechanism allows the touch screen to move linearly and activate the tactile switch without twisting, no matter where along its surface it is pressed.
One of the major factors for [Michael] was the great feel of the keys on these classic units. Wanting to experiment with different layouts without a lot of rewiring, the idea of keys with individual displays became attractive. Existing parts on the market were prohibitively expensive, however. Instead, [Michael] used a single touchscreen with a switch mounted underneath to provide tactile feedback with a nifty scissor-arm guide mechanism. Combined with individual see-through plastic overlays, the MP-29 has a fully reconfigurable pad of 30 keys with dynamically updatable labels.
It’s a creative choice, and one that looks highly satisfying to use. It has all the tactile benefits of individual keys, both in the keypresses and being able to navigate the keypad without looking. Combined with the benefit of reconfigurable keys thanks to the touch screen underneath, it’s a great way to build a user-interface.
The rest of the calculator design closely mimics the HP-29, though [Michael] is also experimenting with alternative layouts too. There are plenty of religious wars in the calculator community over usability, after all – mostly over which side of the pad has the arithmetic functions.
We’ve lamented the demise of the standalone calculator recently; with so many smart devices around, it’s hard to see it making a major comeback anytime soon. Of course, if you’re opinionated on the topic, sound off in the comments below. Video after the break.
The internet is full of self-proclaimed challenges, ranging from some absolutely pointless fads to well-intended tasks with an actual purpose. In times of TikTok, the latter is of course becoming rarer, as a quick, effortless jump on the bandwagon is just easier for raising your internet points. Cyclists on the other hand love a good challenge where they compete with one another online, testing their skills and gamifying their favorite activity along the way. One option for that is Everesting, where you pick a hill of your choice, and within a single session you ride it up and down as many times as it takes until you accumulated the height of Mount Everest on it. Intrigued by the idea, but not so much its competitive aspect, [rabbitcreek] became curious how long it would take him to reach that goal with his own casual bicycle usage, so he built a bicycle computer to measure and keep track of it.
While the total distance and time factors into the actual challenge, [rabbitcreek]’s primary interest was the accumulated height, so the device’s main component is a BMP388 barometric pressure sensor attached to a battery-powered ESP32. An e-paper display shows the total height and completed percentage, along with some random Everest-related pictures. Everything is neatly packed together in a 3D-printed case that can be mounted on the bicycle’s handlebar, and the STL files are available along with the source code in his write-up.
Buying things to make your life easier certainly has its therapeutic joys, but if you really wanna feel good, you gotta make the thing yourself whenever possible. [Bjørn Brandal] happened to have a two-switch BOSS pedal just lying around, so it made sense to turn it into a wireless page turner for reading sheet music.
As [Bjørn] says, the circuit is simple — just two 1/4″ TRS jacks and an ItsyBitsy nRF52840 Express. The jacks are used to connect to the pedal outputs to the ItsyBitsy, which sends keystrokes over BLE.
The cool thing about this pedal is that it can work with a bunch of programs, like forScore, Abelton Live, Garage Band, and more. The different modes are accessed by holding down both pedals, and there’s confirmation via blinking LED and buzzing buzzer.
Our favorite part has to be the DIY light guide [Bjørn] that bends the ItsyBitsy’s RGB LED 90° and points it out the front of the enclosure. Nicely done!
When we think injection molding, the first thing that comes to mind is highly automated production lines pumping out thousands of parts an hour. However, the very same techniques are able to be scaled down to a level accessible by the DIYer, as [The CrafsMan] demonstrates.
Using a compact, hand-actuated injection moulder, [The Crafsman] demonstrates the basic techniques behind small-scale injection molding. The PIM-Shooter Model 150A in question is designed to work with low melting point plastics like polypropylene and low density polyethylene, and can use aluminium molds which are much cheaper to make than the typical steel molds used in industry.
However, the real game changer is when [The Crafsman] busts out his silicone mold making techniques, and applies them to injection molding. By making molds out of silicone, they can be created far more cheaply and easily without the requirement of heavy CNC machinery to produce the required geometry. With the right attention to detail, it’s possible to get good results without having to invest in a custom aluminium mold at all.
Terrestrial radio is all well and good, but it limits you to listening to local stations. [Nick Koumaris] lives in a small town in Southern Greece, and his favorite stations sadly don’t transmit in his area. Thus, an internet radio was the natural solution.
[David Watts] did a similar build, throwing the hardware inside a stunning Roberts RM20 radio from the 1970s.While a Raspberry Pi is a common way to go in these situations, an ESP32 has enough grunt to do the job without the long boot times that come with running a full Linux distribution. Combined with a VS1503 MP3 decoder board and a PAM8403 amplifier, it’s more than capable of tuning in streams online. [Nick] went with a retro-look interface on an LCD, using a Nextion part for its onboard controller and in-built GUI tools. Taking inspiration from the project, [David Watts] executed a similar build, but instead used an Arduino Nano to interface the controls on a vintage Roberts RM20 radio instead.
While we’ve all got smartphones we can use to listen to content online, it can be nice to use a device that allows us to put on some music without constant notifications and chimes every time an email comes in or a government scandal erupts in a nearby country. When building your own radio, you can tailor the interface to suit your tastes – like this build that lets users scan the globe for a station to listen to. Video after the break.
As a kid, one of the stories my dad told me was about mowing a fairly large field of grass on the farm with a gas-powered push mower. One day, some sort of farm tool was left in the field and the old industrial mower shredded it, sending a large piece of sharp metal hurtling toward his leg. Luckily for my dad, the large plastic wheel managed to stop the piece of metal, destroying the wheel. My grandfather was frustrated that he needed to repair the lawnmower but was grateful that my dad still had both feet attached.
Of course, this story was used as a lesson for me not to gripe about having to mow the lawn when it was my turn, but there was also the lesson that lawnmowers can be dangerous. [DuctTape Mechanic] took it upon himself to see if he could prevent that sort of accident altogether and has created an automatic safety shutdown mechanism for his family lawnmower. (Video embedded below.)
This uses an inductive sensor that can detect metal before it gets sucked into the mower itself. The sensor trips a relay which forcibly shuts the mower down by grounding the ignition coil. While it doesn’t physically stop the blade like other safety mechanisms, it does prevent a situation from escalating by turning off power to the blade as soon as possible. Getting to the ignition coil wasn’t easy as it required getting deep into the engine itself, but now [DuctTape Mechanic] has a mower that could be expanded further with things such as with a capacitive sensor or more smarts to determine if it is detecting underground or above ground metal.
Someday we’ll have robotic mowers, but until then, we laud the efforts of hackers out there trying to make the world a little safer.
