This Flow Battery Operates With No Pump Required

March 27, 2026 by Lewin Day 4 Comments

Flow batteries are rather unique. They generate electricity by the combination of two fluids flowing on either side of a membrane. Typically, this involves the use of some kind of pump to get everything moving. However, [Dusan Caf] has demonstrated another way to make a flow battery operate.

[Dusan]’s build is a zinc-iodide flow battery. It uses two 3D printed reservoirs, each holding a ZnI₂ solution and a graphite electrode. Unlike traditional flow batteries, there is no mechanism included to mechanically push the fluid around. Instead, fluid motion is generated by the magnetohydrodynamic effect, which you may know from that Japanese boat that didn’t work very well.

When charging the liquid-based cell, current flows through the conductive electrolyte that sits between both electrodes. This sees zinc electroplated onto the graphite anode, while iodide ions are oxidized at the cathode. There’s also a permanent magnet installed beneath the electrodes, which provides a stable magnetic field. This field, combined with the current flowing through the electrolyte, sees the Lorentz force pushing the electrolyte along, allowing the flow battery to operate. When the cell is being discharged, the reactions happen in reverse, with the flow through the electrodes changing direction in turn. Neatly, as current draw or supply increases, the flow rate increases in turn, naturally regulating the system.

[Dusan] notes this isn’t feasible for large batteries, due to the limited flow rate, but it’s fine for small-scale demos regarding the operation of a flow battery. We’ve featured some more typical flow battery designs in the past, too.

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Momentus Clock Aims To Find Meaning

March 26, 2026 by Lewin Day 8 Comments

A lot of the time, we must assign our own meaning to the numbers on the clock. 8:30 AM is work kicking off, 12 PM is lunch, and 5PM is when the corporate chains release us to what’s left of the day. If you’d rather the clock tell you what’s special about the current time, though, you might like this project from [Andy Isaacson].

It’s called Momentous—”a clock to make every minute meaningful” in [Andy’s] own words. The concept is simple—for each minute, the clock digs up some random mathematical fact relevant to the current time. For example, you might think of 3:14 as Pi o’clock, but Momentous also notes that the sequence “314” shows up at the 856th decimal of e. Useful? Probably not. Fun? If you like numbers, then very!

[Andy] wrote Momentous in Typescript with React Native and Expo. Baked into the app is a computed list of fun number facts for every conceivable time from 00:00 to 23:59. All these timely numbers were processed through a “fact generation” algorithm to dig up mathly tidbits. Do they contain primes? Do the numbers show up in a famous irrational number sequence? Are they palindromic, or can some neat facts be gleaned from Wikipedia? Maybe the current time shows up in your best friend’s phone number! Momentous uses all these and more to make every minute of the day a little bit more interesting.

You can check out the clock for yourself in your web browser. Alternatively, you can install it on your iPhone if you so desire. We feature all kinds of fun clocks here, from the wordy to the absurdy. If you’re cooking up your own timely hacks, we always love to to hear about them on the tipsline!

3D Print Becomes Cast Iron Wrench Via Microwave

March 26, 2026 by Lewin Day 32 Comments

Consumer-grade 3D printing is good for prototyping and making relatively soft plastic stuff. If you wanna make tough things, though, it’s really hard to beat the strength of metal. [Shake the Future] has produced a guide on using 3D printing in a process to produce solid parts out of actual cast iron.

The concept is simple. [Shake the Future] uses silicon carbide crucibles, which can heat up by absorbing microwave energy. Put one in an insulated container, dump some metal in, and throw it in a microwave, and soon enough you have a pot of molten metal you can use to cast stuff.

Let’s say you want to make an adjustable wrench, which is how [Shake the Future] demonstrates this technique. The first step is to print the wrench parts in plastic, such as PLA. These parts are then packed into fine sand to create casting molds. The PLA is burned out of the mold, leaving a negative imprint of the geometry. Molten cast iron can then be poured into the mold to create the part in solid metal.

It’s a messy technique that requires a lot of manual labor, but it does work quite well. There are some tricks to learn, though, particularly when it comes to successfully casting parts with holes or fine geometric features.

And before you think that you’re going to put the hardware store out of business, it should also be noted that it failed on first encounter with a real-world nut. The thinnest part by the screw just wasn’t strong enough.

Still, it’s a great demo, and if you’ve ever wanted to make a bespoke cast iron part of your own, this work may be very relevant to you. Alternatively, consider learning about DIY aluminium casting—just consider the pitfalls involved.

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VGA Output From A PIC18

March 25, 2026 by Lewin Day 6 Comments

In the maker world, it’s the Arduino and ESP32 lines that get the lion’s share of attention. However, you can do fantastic things with PIC chips, too, if you put the dev time in—it’s just perhaps less likely another maker has done so before you. A great example is this VGA output project from [grecotron].

A PIC18F47K42 is perhaps not the first part you would reach for to pursue any sort of video-based project. However, with the right techniques, you can get the 8-bit microcontroller pumping out the pixels surprisingly well. [grecotron] was able to get the chip outputting to a VGA monitor at a resolution of 360 x 480 with up to 16 colors. It took some careful coding to ensure the chip could reliably meet the timing requirements for the standard and to get HSYNC, VSYNC, and the color signals all dancing in harmony. Aiding in this regard was that the chip was clocked with a 14.3182 MHz crystal to make it easy to divide down from all the internal timers as needed. Supporting hardware is light, too—primarily consisting of a VGA connector, a couple of multiplexers, and resistor ladder DACs for the color signals. Files are on Github for those interested in deeper detail on the work.

VGA output is possible to implement on all kinds of microcontrollers—and even a bunch of raw logic if you know what you’re doing. If you’re pursuing your own video output wizardry, be sure to let us know on the tipsline.

3D Printed Robot Arm Built For Learning Purposes

March 24, 2026 by Lewin Day 4 Comments

If you want to work with robots you can do all sorts of learning with software and simulation, but nothing quite beats getting to grips with real machinery. That was the motivation for [James Gullberg] to build this impressive robot arm.

Featuring six degrees of freedom, the robot arm is mostly constructed of 3D printed components. This let [James] experiment with a wide variety of joint and reducer designs for the sake of learning and investigation. The base of the robot uses a fairly conventional planetary gear drive, while shoulder and elbow joints rely on split-ring planetary gearboxes to allow for high torque density with regards to size. [James] implemented a neat sensing technique here, integrating alternating magnets into the output ring gear which are monitored via a magnetic encoder. The wrist joint switches things up again, running via an inverted belt differential.

Running the show is an STM32 microcontroller, which talks to all the encoders, communicates with a Raspberry Pi over CAN bus, and handles all the necessary PID control loops and step generation for the drive motors. The plan is to run higher-level control on the Raspberry Pi which will run a ROS 2-based software stack. Already, the various joints look smooth and impressive in motion.

If you’re looking to learn about robot arms, you really can’t beat building one. We’ve featured a few projects along these lines before. Most of them aren’t exactly production-line ready, but they will teach you a ton about control, motion planning, and all sorts of associated skills. That experience can be invaluable if you intend to work with robots in industry.

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Building A Monitor Light Bar For Better Productivity

March 24, 2026 by Lewin Day 10 Comments

If you’re intending to work at your desk for long periods of time, good lighting is a must, as it can help stave off eye strain and mental fatigue. It was a desire for more comfortable productivity that drove [Jade] to whip up a monitor-mounted lighting system for her workstation.

The build uses an ESP32 to run the show, with a rotary encoder for manual control and firmware that allows the monitor light to be neatly integrated with Home Assistant. The light itself comes from light strips that feature both warm white and cold white LEDs. Simple MOSFETs are used to control the brightness of the LEDs and which of the warm and cold LEDs are activated at any time. Everything is wrapped up in a 3D printed housing that neatly sits on top of the monitor with the aid of a simple printed clamp. The LED strips also have a nice soft glow thanks to a strip of diffuser material that [Jade] snatched from an old television.

We love a good lighting build, from the work-focused to the creative and beautiful.

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From Zip To Nought: The Rise And Fall Of Iomega

March 24, 2026 by Lewin Day 86 Comments

If you were anywhere near a computer in the mid-to-late 1990s, you almost certainly encountered a Zip drive. That distinctive purple peripheral, with its satisfying clunk as you slotted in a cartridge, was as much a fixture of the era as beige tower cases and CRT monitors. Iomega, the company behind it, went from an obscure Utah outfit to a multi-billion-dollar darling of Wall Street in the span of about two years. And then, almost as quickly, it all fell apart.

The story of Iomega is one of genuine engineering innovation and the fickle nature of consumer technology. As with so many other juggernauts of its era, Iomega was eventually brought down by a new technology that simply wasn’t practical to counter.

The House That Bernoulli Built

Iomega was founded in Utah, in 1980, by Jerome Paul Johnson, David Bailey, and David Norton. The company soon developed a novel approach to removable magnetic storage based on the Bernoulli effect. The Bernoulli Box arrived in 1982, which was a drive relying on PET film disks spun at 1500 RPM inside a rigid, removable cartridge. The airflow generated by the spinning disk pulled the media down toward the read/write head thanks to the eponymous Bernoulli effect. While spinning, the disk would float a mere micron above the head surface on a cushion of air. If the power cut out or the drive otherwise failed, the disk simply floated away from the head rather than crashing into it—a boon over contemporary hard drives for which head crashes were a real risk. The Bernoulli Box made them essentially impossible. Continue reading “From Zip To Nought: The Rise And Fall Of Iomega” →