A photo of a large warehouse with many skylights and windows near the roof. In the middle of the image extending out into the distance are hundreds of grey refractory bricks stacked on top of a smaller set of brown bricks stacked on top of pallets. There appear to be rails on the floor of the warehouse and small dollies underneath the pallets.

Thermal Batteries For Lower Carbon Industrial Processes

Heating things up is one of the biggest sources of cost and emissions for many industrial processes we take for granted. Most of these factories are running around the clock so they don’t have to waste energy cooling off and heating things back up, so how can you match this 24/7 cycle to the intermittent energy provided by renewables? This MIT spin-off thinks one solution is thermal storage refractory bricks.

Electrified Thermal Solutions takes the relatively simple technology of refractory brick to the next level. For the uninitiated, refractory bricks are typically ceramics with a huge amount of porosity to give them a combination of high thermal tolerance and very good insulating properties. A number of materials processes use them to maximize the use of the available heat energy.

While the exact composition is likely proprietary, the founder’s Ph.D. thesis tells us the bricks are likely a doped chromia (chrome oxide) composition that creates heat in the brick when electrical energy is applied. Stacked bricks can conduct enough current for the whole stack to heat up without need for additional connections. Since these bricks are thermally insulating, they can time shift the energy from solar or wind energy and even out the load. This will reduce emissions and cost as well. If factories need to pipe additional grid power, it would happen at off-peak hours instead of relying on the fluctuating and increasing costs associated with fossil fuels.

If you want to implement thermal storage on a smaller scale, we’ve seen sand batteries and storing heat from wind with water or other fluids.

Front and back of the replacement OLED module by Sir68k

Reviving A Piece Of Yesterday’s Tomorrow

To anyone who remembers Y2K, Sony’s MiniDisc format will probably always feel futuristic. That goes double for Sony’s MZ-RH1, the last MiniDisk recorder ever released, back in 2006. It’s barely larger than the diminutive disks, and its styling is impeccable. There’s a reason they’ve become highly collectible and sell for insane sums on e-Bay.

Unfortunately, they come with a ticking time-bomb of an Achilles heel: the first-generation OLED screens. Failure is not a question of if, but when, and many units have already succumbed. Fortunately enterprising hacker [Sir68k] has come up with replacement screen to keep these two-decade old bits of the future alive.

Replacement screens glowing brightly, and the custom firmware showing track info, something you’d never see on a stock RH1.

Previous revisions required some light surgery to get the twin OLED replacement screens to fit, but as of the latest incarnation (revision F+), it’s now a 100% drop-in replacement for the original Sony part. While it is a drop-in, don’t expect it to be easy. The internals are very densely packed, and fairly delicate — both in the name of miniaturization. You’ll need to break out the micro-screwdrivers for this one, and maybe some magnifiers if your eyes are as old as ours. At least Sony wasn’t gluing cases together back in 2006, and [Sir68k] does provide a very comprehensive repair guide.

He’s even working on new firmware, to make what many considered best MD recorder better than ever. It’s not ready yet, but when it is [Sir68k] promises to open-source the upgrade. The replacement screens are sadly not open source hardware, but they’re a fine hack nonetheless.

We may see more MiniDisc hacks as the format’s apparent revival continues. Things like adding Bluetooth to the famously-cramped internals, or allowing full data transfer — something Sony was unwilling to allow until the RH1, which is one of the reasons these units are so desirable.

A diagram with one Tag and two Base Stations.

Using Ultra-Wideband For 3D Location And Tracking

Interested in playing with ultra-wideband (UWB)? [Jaryd] recently put together a fairly comprehensive getting started guide featuring the AI Thinker BU03 that looks like a great place to start. These modules can be used to determine distance between two of them to an accuracy in the order of 10 centimeters, and they can do so in any orientation and with obstacles in the line of sight. It is possible to create a network of these UWB modules to get multiple distance measurements at once and enable real-time 3D tracking for your project.

[Jaryd] gathers up nine UWB modules and uses a Raspberry Pi Pico for command and control purposes. He explains how to nominate the “tag” (the device being tracked) and the “base stations” (which help in locating the tag). He reports having success at distances of up to about 10 meters and in favorable circumstances all the way up to as much as 30 meters.

If you don’t know anything about UWB and would like a primer on the technology be sure to check out What Is Ultra Wideband?

Lisp In 99 Lines Of C With TinyLisp

As one of the oldest programming languages still in common use today, and essential for the first wave of Artificial Intelligence research during the 1950s and 60s, Lisp is often the focus of interpreters that can run on very low-powered systems. Such is the case with [Robert van Engelen]’s TinyLisp, which only takes 99 lines of C code and happily runs on the Z80-based Sharp PC-G850V(S) pocket computer with its 2.3 kB of internal RAM and native C support.

The full details on how TinyLisp was implemented and how to write it yourself can be found in the detailed article that’s part of the GitHub project. It supports static scoping, double-precision floating point and features 21 Lisp primitives along with a garbage collector. Two versions for the Sharp PC-G850 (using BCD (i.e. NaN) boxing) are provided, along with a number of generic implementations, using either double or single precision floating point types. A heavily commented version is probably the version to keep alongside the article while reading.

TinyLisp is – as the name implies – very tiny, and thus more full-featured Lisp implementations are widely available. This includes two versions – linked at the bottom of the Readme – also by [Robert] that use a gargantuan 1,000 lines of C, providing a more advanced garbage collector and dozens more Lisp primitives to handle things like exceptions, file loading, strings and debug features.

A brown plastic circuit board is visible in the middle of the picture, containing an integrated circuit, a resistor, a diode, two capacitors, and some jumper wires going away to the sides.

A Solderless, Soluble Circuit Board

Anyone who’s spent significant amounts of time salvaging old electronics has probably wished there were a way to take apart a circuit board without desoldering it. [Zeyu Yan] et al seem to have had the same thought, and designed circuit boards that can be dissolved and recycled when they become obsolete. Read the details in the research paper. (PDF)

The researchers printed the circuit boards out of water-soluble PVA, with hollow channels in place of interconnects. After printing the boards, they injected a eutectic gallium-indium liquid metal alloy into these channels, populated the boards with components, making sure that their leads were in contact with the liquid alloy, and finally closed off the channels with PVA glue, which also held the components in place. When the board is ready to recycle, they simply dissolve the board and glue in water. The electric components tend to separate easily from the liquid alloy, and both can be recovered and reused. Even the PVA can be reused: the researchers evaporated the solution left after dissolving a board, broke up the remaining PVA, and extruded it as new filament.
Continue reading “A Solderless, Soluble Circuit Board”

Roll Your Own SSB Receiver

[Paul Maine] was experimenting with GNU Radio and an RTL-SDR dongle. He created an SSB receiver and, lucky for us, he documented it all in a video you can see below. He walks through how to generate SSB, too. If videos aren’t your thing, you can go back to the blog post from [Gary Schafer] that inspired him to make the video, which is also a wealth of information.

There is a little math — you almost can’t avoid it when talking about this topic. But [Paul] does a good job of explaining it all as painlessly as possible. The intuitive part is simple: An AM signal has most of its power in the carrier and half of what’s left in a redundant sideband. So if you can strip all those parts out and amplify just one sideband, you get better performance.

Continue reading “Roll Your Own SSB Receiver”

2025 One Hertz Challenge: Atomic Decay Clock Is Accurate But Not Precise

At this point, atomic clocks are old news. They’ve been quietly keeping our world on schedule for decades now, and have been through several iterations with each generation gaining more accuracy. They generally all work under the same physical principle though — a radio signal stimulates a gas at a specific frequency, and the response of the gas is used to tune the frequency. This yields high accuracy and high precision — the spacing between each “tick” of an atomic clock doesn’t vary by much, and the ticks cumulatively track the time with very little drift.

All of this had [alnwlsn] thinking about whether he could make an “atomic” clock that measures actual radioactive decay, rather than relying on the hyperfine transition states of atoms. Frustratingly, most of the radioactive materials that are readily available have pretty long half-lives — on the order of decades or centuries. Trying to quantify small changes in the energy output of such a sample over the course of seconds or minutes would be impossible, so he decided to focus on the byproduct of decay — the particles being emitted.

He used a microcontroller to count clicks from a Geiger-Müller tube, and used the count to calculate elapsed time by multiplying by a calibration factor (the expected number of clicks per second). While this is wildly inaccurate in the short term (he’s actually used the same system to generate random numbers), over time it smooths out and can provide a meaningful reading. After one year of continuous operation, the counter was only off by about 26 minutes, or 4.4 seconds per day. That’s better than most mechanical wristwatches (though a traditional Rubidium atomic clock would be less than six milliseconds off, and NIST’s Strontium clock would be within 6.67×10-11 seconds).

The end result is a probabilistic radiometric timepiece that has style (he even built a clock face with hands, rather than just displaying the time on an LCD). Better yet, it’s got a status page where you can check on on how it’s running. We’ve seen quite a few atomic clocks over the years, but this one is unique and a great entry into the 2025 One Hertz Challenge.