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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Add Wood Grain Texture To 3D Prints – With A Model Of A Log

June 3, 2025 by Donald Papp 34 Comments

Adding textures is a great way to experiment with giving 3D prints a different look, and [PandaN] shows off a method of adding a wood grain effect in a way that’s easy to play around with. It involves using a 3D model of a log (complete with concentric tree rings) as a print modifier. The good news is that [PandaN] has already done the work of creating one, as well as showing how to use it.

The model of the stump — complete with concentric tree rings — acts as a modifier for the much-smaller printed object (in this case, a small plate).

In the slicer software one simply uses the log as a modifier for an object to be printed. When a 3D model is used as a modifier in this way, it means different print settings get applied everywhere the object to be printed and the modifier intersect one another.

In the case of this project, the modifier shifts the angle of the fill pattern wherever the models intersect. A fuzzy skin modifier is used as well, and the result is enough to give a wood grain appearance to the printed object. When printed with a wood filament (which is PLA mixed with wood particles), the result looks especially good.

We’ve seen a few different ways to add textures to 3D prints, including using Blender to modify model surfaces. Textures can enhance the look of a model, and are also a good way to hide layer lines.

In addition to the 3D models, [PandaN] provides a ready-to-go project for Bambu slicer with all the necessary settings already configured, so experimenting can be as simple as swapping the object to be printed with a new 3D model. Want to see that in action? Here’s a separate video demonstrating exactly that step-by-step, embedded below.

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Rusty bathtub outdoors on equally rusty car springs

Hot Rod Backyard Bath On Steel Spring Legs

May 31, 2025 by Heidi Ulrich 16 Comments

In a fusion of scrapyard elegance and Aussie ingenuity, [Mark Makies] has given a piece of old steel a steamy second life with his ‘CastAway Tub’. Call it a bush mechanic’s fever dream turned functional sculpture, starring two vintage LandCruiser leaf springs, and a rust-hugged cast iron tub dug up after 20 years in hiding. And put your welding goggles on, because this one is equal parts brute force and artisan flair.

What makes this hack so bold is, first of all, the reuse of unforgiving spring steel. Leaf springs, notoriously temperamental to weld, are tamed here with oxy-LPG preheating, avoiding thermal shock like a pro. The tub sits proudly atop a custom-welded frame shaped from dismantled spring packs, with each leaf ground, clamped, torched, and welded into a steampunk sled base. The whole thing looks like it might outrun a dune buggy – and possibly bathe you while it’s at it. It’s a masterclass in metalwork with zero CAD, all intuition, and a grinder that’s seen things.

Inspired? For those with a secret love for hot water and hot steel, this build is a blueprint for turning bush junk into backyard art. Read up on the full build at Instructables.