servo

458 Articles

Multifunctional USB controlled PCB on blue background

How A Tiny Relay Became A USB Swiss Army Knife

April 5, 2025 by 17 Comments

Meet the little board that could: [alcor6502]’s tiny USB relay controller, now evolved into a multifunction marvel. Originally built as a simple USB relay to probe the boundaries of JLCPCB’s production chops, it has become a compact utility belt for any hacker’s desk drawer. Not only has [alcor6502] actually built the thing, he even provided instructions. If you happened to be at Hackaday in Berlin, you now might even own one, as he handed out twenty of them during his visit. If not, read on and build it yourself.

This thing is not just a relay, and that is what makes it special. Depending on a few solder bridges and minimal components, it shape-shifts into six different tools: a fan controller (both 3- and 4-pin!), servo driver, UART interface, and of course, the classic relay. It even swaps out a crystal oscillator for USB self-sync using STM32F042‘s internal RC – no quartz, less cost, same precision. A dual-purpose BOOT0 button lets you flash firmware and toggle outputs, depending on timing. Clever reuse, just like our mothers taught us.

It’s the kind of design that makes you want to tinker again. Fewer parts. More function. And that little smile when it just works. If this kind of clever compactness excites you too, read [alcor6502]’s build log and instructions here.

The Mysterious And Important Work Of Prop Design On Severance

March 13, 2025 by 28 Comments

Have you seen Severance? Chances are good that you have; the TV series has become wildly popular in its second season, to the point where the fandom’s dedication is difficult to distinguish from the in-universe cult of [Kier]. Part of the show’s appeal comes from its overall aesthetic, which is captured in this description of the building of one of the show’s props.

A detailed recap of the show is impossible, but for the uninitiated, a mega-corporation called Lumon has developed a chip that certain workers have implanted in their brains to sever their personalities and memories into work and non-work halves. The working “Innies” have no memory of what their “Outies” do when they aren’t at work, which sounds a lot better than it actually ends up being. It’s as weird as it sounds, and then some.

The prop featured here is the “WoeMeter” from episode seven of season two, used to quantify the amount of woe in a severed worker — told you it was weird. The prop was built by design house [make3] on a short timeline and after seeing only some sketches and rough renders from the production designers, and had to echo the not-quite-midcentury modern look of the whole series. The builders took inspiration from, among other things, a classic Nagra tape recorder, going so far as to harvest its knobs and switches to use in the build. The controls are all functional and laid out in a sensible way, allowing the actors to use the device in a convincing way. For visual feedback, the prop has two servo-operated meters and a string of seven-segment LED displays, all controlled by an ESP-32 mounted to a custom PCB. Adding the Lumon logo to the silkscreen was a nice touch.

The prop maker’s art is fascinating, and the ability to let your imagination run wild while making something that looks good and works for the production has got to be a blast. [make3] really nailed it with this one.

Thanks to [Aaron’s Outie] for the tip.

Gimbal Clock Relies On Servos For Its Cool Movements

January 16, 2025 by 1 Comment

In the annals of human history, clocks got boring there for a while. Most were just variations on hands spinning in a circle, with the occasional tweeting bird mechanism to liven things up. These days, we’re treated to all kinds of original and oddball designs, like this neat gimbal clock from [Twisted&Tinned].

The concept of the build is straightforward enough. It has four main vertical arms, each with a servo at the base that rotates about a vertical axis. Upon each arm are between one and three servos which rotate 3D printed structures in the shape of numbers. A Wemos D1 Mini microcontroller commands the servos to the correct positions to display the current time. It also uses its WiFi connection to get accurate time updates directly from a network time server.

It’s quite an artistic build—and it’s rather enjoyable to watch this one flex and twist its way into displaying the right time. It’s also easier to read at a glance than some of the more unintelligible designs out there. Indeed, we see all kinds of neat and innovative clocks around these parts.

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Gas Gauge Upgrade Keeps VW Restoration Classy

December 4, 2024 by 45 Comments

Getting every detail perfectly right is often the goal in automotive restorations, and some people will go to amazing lengths to make sure the car looks and acts just like it did when it rolled off the dealer’s lot all those decades ago. That ethos can be pushed a little too far, though, especially with practical matters like knowing how much gas is left in the tank. Get that wrong and you’ll be walking.

Unwilling to risk that cruel fate with his restoration of 1978 Volkswagen Bus, [Pegork] came up with a replacement fuel gauge that looks identical to the original meter, but actually works. The gas gauges on ’60s and ’70s VWs were notoriously finicky, and when they bothered to work at all they were often wildly inaccurate. The problem was usually not with the sender unit in the tank, but the gauge in the dash, which used a bimetallic strip heated by a small coil of wire to deflect a needle. [Pegor]’s “SmoothBus” modification replaces the mechanical movement with a micro servo to move the needle. The variable voltage coming back from the fuel sender is scaled through a voltage divider and read by an analog input on an ATtiny85, which does a little algorithmic smoothing to make sure the needle doesn’t jump around too much. A really nice addition is an LED low fuel indicator, a feature that would have saved us many walks to the gas station back in our VW days. Except for the extra light, the restored gauge looks completely stock, and it works far better than the original.

Hats off to [Pregor] for this fantastic restomod. As we’ve noted before, classic VWs are perhaps the most hackable of cars, and we applaud any effort to keep these quirky cars going.

A Robot Meant For Humans

November 26, 2024 by 11 Comments

Although humanity was hoping for a more optimistic robotic future in the post-war era, with media reflecting that sentiment like The Jetsons or Lost in Space, we seem to have shifted our collective consciousness (for good reasons) to a more Black Mirror/Terminator future as real-world companies like Boston Dynamics are actually building these styles of machines instead of helpful Rosies. But this future isn’t guaranteed, and a PhD researcher is hoping to claim back a more hopeful outlook with a robot called Blossom which is specifically built to investigate how humans interact with robots.

For a platform this robot is not too complex, consisting of an accessible frame that can be laser-cut from wood with only a few moving parts controlled by servos. The robot is not too large, either, and can be set on a desk to be used as a telepresence robot. But Blossom’s creator [Michael] wanted this to help understand how humans interact with robots so the latest version is outfitted not only with a large language model with text-to-speech capabilities, but also with a compelling backstory, lore, and a voice derived from Animal Crossing that’s neither human nor recognizable synthetic robot, all in an effort to make the device more approachable.

To that end, [Michael] set the robot up at a Maker Faire to see what sorts of interactions Blossom would have with passers by, and while most were interested in the web-based control system for the robot a few others came by and had conversations with it. It’s certainly an interesting project and reminds us a bit of this other piece of research from MIT that looked at how humans and robots can work productively alongside one another.

A black and white robot arm is held in a human hand against a grey background. Next to it, in white lettering, is the Arduino logo and the text, "Mini Robotic Arm."

Mini Robotic Arm Lets You Start Your Own Mini Assembly Line

October 24, 2024 by 25 Comments

Automating tasks with a robot sounds appealing, but not everyone has the budget for an Aismo or Kuka. [FABRI Creator] has a great tutorial on how to build your own mini robotic arm for small, repeatable tasks.

Walking us through the entire build, step-by-step, [FABRI Creator] shows us how to populate the custom-designed PCB and where to put every servo motor and potentiometer to bring the creation to life. This seems like a great project to start with if you haven’t branched out into motion systems before since it’s a useful build without anything too complicated to trip up the beginner.

Beyond the usual ability to use the arm to perform tasks, this particular device uses an Arduino Nano to allow you to record a set of positions as you move the arm and to replay it over and over. The video shows the arm putting rings on a stand, but we can think of all kinds of small tasks that it could accomplish for us, letting us get back to writing or hacking.

If controlling a robot arm with potentiometers sounds familiar, maybe you remember this robot arm with an arm-shaped controller.

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Should You Run Servo Horns Or Direct Couplings In Your RC Planes?

September 7, 2024 by 22 Comments

Whenever you buy a servo, it usually comes with a little baggie full of various plastic horns. Most of us pick our favorite and use it in our projects. Some of us hack them up, glue them back together, and do all kinds of weird things with them. And others skip them entirely, going for direct drive instead. In a new video, [Dynamix Systems] explores when going direct drive is the right solution.

The video primarily concerns servos as they’re used in the context of aero modeling. In this regard, the video points out that while stock servo horns are easy to use, they can be cumbersome and clumsy. For example, you often end up with horns and control linkages protruding out into the airstream, adding drag and generally making things a bit inelegant. They can also snag on things and easily damage your servos or controls.

Using direct shaft couplers can be a much tidier solution in some respects. The servo can be coupled directly to the axis of motion, allowing it to be hidden inside a wing or tail surface. It can require a little more finesse in installation and design, but they’re much less likely to snag on things or be damaged. There’s also a drag benefit if you do it right. [Dynamix Systems] notes that you’ll want to source some shaft couplers to do this properly, which you can make yourself or buy online fairly easily.

It’s great to see how tidy direct drive really is. We’ve seen some other nifty servo tricks of late, too. Video after the break.

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