Build Yourself A Useful Resistor Decade Box

November 22, 2024 by Lewin Day 18 Comments

If you’ve ever worked with guitar pedals or analog audio gear, you’ve probably realized the value of a resistor decade box. They substitute for a resistor in a circuit and let you quickly flick through a few different values at the twist of a knob. You can still buy them if you know where to look, but [M Caldeira] decided to build his own.

At its core, the decade box relies on a number of 11-position rotary switches. Seven are used in this case—covering each “decade” of resistances, from 1 ohm to 10 ohm and all the way up to 1 megaohm. The 11 positions on each switch allows the selection of a given resistance. For example, position 7 on the 100 ohm switch selects 700 ohms, and adds it to the total resistance of the box.

[M Caldeira] did a good job of building the basic circuit, as well as assembling it in an attractive, easy-to-use way. It should serve him well on his future audio projects and many others besides. It’s a simple thing, but sometimes there’s nothing more satisfying than building your own tools.

We’ve seen other neat designs like this in the past, including an SMD version and this neat digital decade box. Video after the break.

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Enhiker Helps You Decide If Its A Good Day To Hike

November 22, 2024 by Lewin Day 10 Comments

Many of us check the weather before heading out for the day — we want to know if we’re dressed (or equipped) properly to handle what Mother Nature has planned for us. This is even more important if you’re going out hiking, because you’re going to be out in a more rugged environment. To aid in this regard, [Mukesh Sankhla] built a tool called Enhiker.

The concept is simple; it’s intended to tell you everything you need to know about current and pending conditions before heading out on a hike. It’s based around Unihiker, a single-board computer which also conveniently features a 2.8-inch touch screen. It’s a quad-core ARM device that runs Debian and has WiFi and Bluetooth built in, too. The device is able to query its GPS/GNSS receiver for location information, and then uses this to get accurate weather data online from OpenWeatherMap. It makes some basic analysis, too. For example, it can tell you if it’s a good time to go out, or if there’s a storm likely rolling in, or if the conditions are hot enough to make heat stroke a concern.

It’s a nifty little gadget, and it’s neat to have all the relevant information displayed on one compact device. We’d love to see it upgraded further with cellular connectivity in addition to WiFi; this would make it more capable when out and about.

We’ve seen some other neat hiking hacks before, too, like this antenna built with a hiking pole. Meanwhile, if you’ve got your own neat hacks for when you’re out on the trail, don’t hesitate to let us know!

FREE-WILi Turns DC32 Badge Into Hardware Dev Tool

November 21, 2024 by Tom Nardi 14 Comments

With few exceptions, electronic event badges are often all but forgotten as soon as the attendee gets back home. They’re a fun novelty for the two or three days they’re expected to be worn, but after that, they end up getting tossed in a drawer (or worse.) As you might imagine, this can be a somewhat depressing thought thought for the folks who design and build these badges.

But thanks to a new firmware released by the FREE-WILi project, at least one badge is going to get a shot at having a second life. When loaded onto the RP2350-powered DEF CON 32 badge, the device is turned into a handy hardware hacking multi-tool. By navigating through a graphical interface, users will be able to control the badge’s GPIO pins, communicate over I2C, receive and transmit via infrared, and more. We’re particularly interested in the project’s claims that the combination of their firmware and the DC32 badge create an ideal platform for testing and debugging Simple Add-Ons (SAOs).

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[James] and his Lemontron portable 3D printer

If Life Gives You Lemons, Build This Lemontron

November 20, 2024 by Heidi Ulrich 12 Comments

What if your 3D printer could fit in a box of filament but still rival the build plate size of heavyweights? Enter the Lemontron, a free and open source portable printer making waves in the maker community for its compact form factor and budget-friendly price. Watch [James]’ video on his build story here. Built around the Positron drive—a unique mechanism introduced by [Kralyn] in 2022—the Lemontron is the latest evolution of this innovative design. Although Kralyn mysteriously disappeared, their work inspired other projects like the Positron JourneyMaker and this Lemontron.

The Lemontron started as a unibody chassis mod for the JourneyMaker but grew into a complete redesign, cutting costs in half without sacrificing performance. By eliminating expensive CNC parts, it’s entirely made from off-the-shelf components, bringing the build cost to just $413. Compare that to $800 for the JourneyMaker and $699 for the Positron v3.2 kit.

Recent video updates show the Lemontron in action, printing impressively large and complex models. It tackled a marble run with 80-degree unsupported overhangs and a ‘comically large’ Benchy, proving its capability. Its compact design, paired with robust performance, is an exciting alternative for tinkerers seeking quality on a budget.

The Lemontron is in its final development stages, with frequent updates dropping on its YouTube channel. If you’re in the market for a more “traditional” mini-printer, check out this cool suitcase model from 2014.

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Power Supply With Benchtop Features Fits In Your Pocket

November 19, 2024 by Donald Papp 42 Comments

[CentyLab]’s PocketPD isn’t just adorably tiny — it also boasts some pretty useful features. It offers a lightweight way to get a precisely adjustable output of 0 to 20 V at up to 5 A with banana jack output, integrating a rotary encoder and OLED display for ease of use.

PocketPD leverages USB-C Power Delivery (PD), a technology with capabilities our own [Arya Voronova] has summarized nicely. In particular, PocketPD makes use of the Programmable Power Supply (PPS) functionality to precisely set and control voltage and current. Doing this does require a compatible USB-C charger or power bank, but that’s not too big of an ask these days.

Even if an attached charger doesn’t support PPS, PocketPD can still be useful. The device interrogates the attached charger on every bootup, and displays available options. By default PocketPD selects the first available 5 V output mode with chargers that don’t support PPS.

The latest hardware version is still in development and the GitHub repository has all the firmware, which is aimed at making it easy to modify or customize. Interested in some hardware? There’s a pre-launch crowdfunding campaign you can watch.

It’s A Soldering Iron! It’s A Multimeter! Relax! It’s Both!

November 15, 2024 by Al Williams 23 Comments

Imagine this. A young person comes to you wanting to get started in the electronic hobby. They ask what five things should they buy to get started. Make your list. We’ll wait. We bet we can guess at least two of your items: a multimeter, and a soldering iron. [LearnElectroncsRepair] recently showed us a review of the Zotek Zoyi ZT-N2 which is a soldering iron and a multimeter in one unit. You can watch the video review below.

Honestly, when we heard about this, we didn’t think much of the combination. It doesn’t seem like having your probe get red hot is a feature. However, the probe tip replaces the soldering iron tip, so you are either soldering or measuring, but not both at the same time.

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A Vintage Radiator Core, From Scratch

November 13, 2024 by Jenny List 25 Comments

There are sadly few 1914 Dennis fire engines still on the road, so when the one owned by Imperial College in London needs a spare part, it can not be ordered from the motor factors and must be made from scratch. Happily, [Andy Pugh] is an alumnus with the required metalworking skills, so in the video below we see him tackling the manufacture of flattened brass tubes for its radiator core.

Forming a round tube to a particular shape is done by pulling it through a die whose profile gradually changes from round to the desired shape. We see him make a couple of tries at this, finally succeeding with one carefully designed to have a constant circumference. The use of CNC machining is something that wouldn’t have been available in the Dennis works in the early 20th century, so we can marvel at the skills of the machinists back then who made the original. Here in 2024 he makes a drawing rig with a geared chain drive suitable for larger scale production.

The video is both a fascinating look at tube drawing and a mind-cleansing piece of workshop observation, and we have to say we enjoyed watching it. If [Andy]’s name sounds familiar to you, this might be because this isn’t the first go he’s had at manufacturing vehicle parts.

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