Mini Car Racing Game Really Shows Off Multicolor Printing

July 16, 2025 by Donald Papp 12 Comments

Quality 3D printing is a common hobbyist tool nowadays, and [wontonnn]’s mini arcade car racing game really shows off how 3D printing can bring parts from functional to fantastic. There are quite a few details we like in [wontonn]’s design, so let’s take a closer look.

The mini mechanical game is one of those treadmill-based car racing games in which the player navigates a little car between an onslaught of belt-borne obstacles. A little DC motor spins things up in a modular side assembly, and a hand-cranked option is available. The player’s car attaches via a magnet to a steering arm; if the player’s car gets knocked off the magnet, game over.

Treadmill belt segments print as large pre-assembled pieces, with ends that snap together without connectors. Belts like this are sometimes tricky, so this is worth keeping in mind should one ever need a similar part. Since there are no external fasteners or hardware to depend on, one could resize it easily to suit their own project purposes.

The finishing touches on the whole assembly look great. It used to be that the sort of colors and lettering seen here would come from a sticker or label, but [wontonn] gets clean lines and colors by raising (or sinking) different parts of the design. The checkerboard pattern, for example, has the light squares raised for printing in a different color.

Electromechanical arcade games have an appeal all their own, being a fusion of both mechanical and electric design that comes together in a special way. Want to make your own? Get inspired by the classic Lunar Lander reimagined, or check out this LEGO treadmill racer that takes an entirely different approach to the concept.

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Wire Like A Pro: Peeking Into Wire Harness Mastery

July 12, 2025 by Matt Varian 26 Comments

There are many ways to learn, but few to none of them compare to that of spending time standing over the shoulder of a master of the craft. This awesome page sent in by [JohnU] is a fantastic corner of the internet that lets us all peek over that shoulder to see someone who’s not only spent decades learning the art of of creating cabl e harnesses, but has taken the time to distill some of that vast experience for the rest of us to benefit from.

This page is focused on custom automotive and motorcycle modifications, but it’s absolutely jam-packed with things applicable in so many areas. It points out how often automotive wiring is somewhat taken for granted, but it shouldn’t be; there are hundreds of lines, all of which need to work for your car to run in hot and cold, wet and dry. The reliability of wiring is crucial not just for your car, but much larger things such as the 530 km (330 mi) of wiring inside an Airbus A380 which, while a large plane, is still well under 100 m in length.

This page doesn’t just talk about cable harnessing in the abstract; in fact, the overwhelming majority of it revolves around the practical and applicable. There is a deep dive into wiring selection, tubing and sealing selection, epoxy to stop corrosion, and more. It touches on many of the most common connectors used in vehicles, as well as connectors not commonly used in the automotive industry but that possess many of the same qualities. There are some real hidden gems in the midst of the 20,000+ word compendium, such as thermocouple wiring and some budget environmental sealing options.

There is far more to making a thing beyond selecting the right parts; how it’s assembled and the tools used are just as important. This page touches on tooling, technique, and planning for a wire harness build-up. While there are some highly specialized tools identified, there are also things such as re-purposed knitting needles. Once a harness is fully assembled it’s not complete, as there is also a need for testing that must take place which is also touched on here.

Thanks to [JohnU] for sending in this incredible learning resource. If this has captured your attention like it has ours, be sure to check out some of the other wire harness tips we’ve featured!

Fingers installing a service loop in a wire in a connector

Are Service Loops A Good Idea?

July 1, 2025 by John Elliot V 23 Comments

Well, here’s an interesting idea: the service loop. Ever heard of it? We haven’t!

In the video, the presenter explains the service loop serves two purposes: on the one hand it may provide strain relief, but chiefly these loops are installed so there will be extra available slack in the cable if you need to rewire it some day to change the configuration of your pinout.

One major problem with the service loop may be that the single turn is enough to create an inductor which will then induce noise and cross-talk all over the place. Our rule of thumb is always to completely unroll wires and cables before using them. Do you have a theory about the benefits or problems with service loops? If you do, we’d love to hear what you think in the comments!

If you’re interested in strain relief, we’ve covered that before, and you don’t need a service loop to do it! Check out Cheap Strain Relief By Casting Hot Glue In A 3D Print and Arduino Uno Strain Relief.

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How To Make A Beautiful Floral Keycap Using Resin

June 26, 2025 by John Elliot V 8 Comments

Here’s a fun build. Over on their YouTube channel our hacker [Atasoy] shows us how to make a custom floral keyboard keycap using resin.

We begin by using an existing keycap as a pattern to make a mold. We plug the keycap with all-purpose adhesive paste so that we can attach it to a small sheet of Plexiglas, which ensures the floor of our mold is flat. Then a side frame is fashioned from 100 micron thick acetate which is held together by sticky tape. Hot glue is used to secure the acetate side frame to the Plexiglas floor, keeping the keycap centered. RTV2 molding silicone is used to make the keycap mold. After 24 hours the silicone mold is ready.

Then we go through a similar process to make the mold for the back of the keycap. Modeling clay is pushed into the back of the keycap. Then silicone is carefully pushed into the keycap, and 24 hours later the back silicone mold is also ready.

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Building Diode And Diode-Transistor Logic Gates

June 20, 2025 by Maya Posch 7 Comments

AND gate implemented as diode-resistor logic. (Credit: Anthony Francis-Jones)

The fun part about logic gates is that there are so many ways to make them, with each approach having its own advantages and disadvantages. Although these days transistor-transistor logic (TTL) is the most common, diode-transistor logic (DTL) once was a regular sight, as well as diode-resistor logic (DRL). These logic gates are the topic of a recent video by [Anthony Francis-Jones], covering a range of logic gates implemented using mostly diodes and resistors.

Of note is that there’s another class of logic gates: this uses resistors and transistors (RTL) and preceded DTL. While DRL can be used to implement AND and OR logic gates, some types of logic gates (e.g. NOT) require an active (transistor) element, which is where DTL comes into play.

In addition to the construction of a rather nifty demonstration system and explanation of individual logic gates, [Anthony] also shows off a range of DTL cards used in the Bendix G-15 and various DEC systems. Over time TTL would come to dominate as this didn’t have the diode voltage drop and other issues that prevented significant scaling. Although the rise of VLSI has rendered DRL and DTL firmly obsolete, they still make for a fascinating teaching moment and remind us of the effort over the decades to make the computing device on which you’re reading this possible.

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Illustrated scheme of Sam Ben Yaakovs concept

Leakage Control For Coupled Coils

June 5, 2025 by Heidi Ulrich 3 Comments

Think of a circuit model that lets you move magnetic leakage around like sliders on a synth, without changing the external behavior of your coupled inductors. [Sam Ben-Yaakov] walks you through just that in his video ‘Versatile Coupled Inductor Circuit Model and Examples of Its Use’.

The core idea is as follows. Coupled inductors can be modeled in dozens of ways, but this one adds a twist: a tunable parameter 𝑥 between k and ₁ (where k is the coupling coefficient). This fourth degree of freedom doesn’t change L_₁, L_₂ or mutual inductance M (they remain invariant) but it lets you shuffle leakage where you want it, giving practical flexibility in designing or simulating transformers, converters, or filters with asymmetric behavior.

If you need leakage on one side only, set 𝑥=k. Prefer symmetrical split? Set 𝑥=1. It’s like parametric EQ, but magnetic. And: the maths holds up. As [Sam Ben-Yaakov] derives and confirms that for any 𝑥 in the range, external characteristics remain identical.

It’s especially useful when testing edge cases, or explaining inductive quirks that don’t behave quite like ideal transformers should. A good model to stash in your toolbox.

As we’ve seen previously, [Sam Ben-Yaakov] is at home when it comes to concepts that need tinkering, trial and error, and a dash of visuals to convey. Continue reading “Leakage Control For Coupled Coils” →

A circuit board is shown, with the tip of a soldering iron applied to a piece of solder wick positioned above a pad.

Making Solder Wick Less Painful

June 4, 2025 by Aaron Beckendorf 28 Comments

For some people (e.g. this author) solder wick is a tool of last resort. Unfortunately, solder suckers and vacuum pumps lose most of their utility when you move from through-hole to SMD components, forcing us to use the dreaded wick. For those of us in this mindset, [nanofix]’s recent video which we’ve placed below the break on tips for solder wick could make desoldering a much less annoying experience.
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