Singapore Branches Out Into Internet Of Trees

December 8, 2022 by 18 Comments

Five years ago, a 38-year-old woman was enjoying an outdoor concert with her family with one of her twin infants in her arms. In the week prior, it had been windy and rainy, but today, the weather was nice, and the concert was crowded. Without warning, a 270-year-old tembusu tree fell on the woman, pinning and ultimately killing her after the other concertgoers couldn’t remove it in time. This tragedy happened in spite of twice-yearly inspections where the tree showed no visual signs of trouble.

It’s exactly this type of incident that Singaporean officials hope to avoid by building an Internet of Trees. The equatorial island nation is home to roughly 5.5 million people, and around 7 million trees — about 6 million of which are tracked by Singapore’s National Parks Board, so that they can be managed remotely with an app. (The Board only tracks trees once they’ve reached a certain size, so we’ll assume that the other million are too young to join the fun just yet.)

While tree-triggered deaths are fairly few and far between, there are plenty of other ‘tree incidents’ that can occur, such as a branch falling, or a tree trunk snapping or uprooting. Depending on the size of the branch, this can be a dangerous nuisance as it could block roads, obscure signage, or destroy property. Thanks to the efforts of the National Parks Board, these incidents have dropped from around 3,000 per year at the turn of the millennium to under 500 per year today.

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Audio Amp Puts VFDs To Work In An Unusual Way

December 8, 2022 by 14 Comments

It’s safe to say that most projects that feature a VFD emphasize the “D” aspect more than anything. Vacuum fluorescent displays are solid performers, after all, with their cool blue-green glow that’s just the right look for lots of retro and not-so-retro builds. But that doesn’t mean there aren’t applications that leverage the “V” aspect, such as this nifty audio preamp using VFDs as active components.

The inspiration behind [JGJMatt]’s build came from the Korg Nutube line of VFD-based low-voltage dual-triode vacuum tubes. Finding these particular components a little on the expensive side, [JGJMatt] turned to the old standby DM160 VFD indicator tube, which is basically just a triode, to see how it would fare as an amp. The circuit takes advantage of the low current and voltage requirements of the VFDs — the whole thing runs from a USB boost converter — by wedging them between a 2N3904 input stage and a 2N2007 MOSFET output. There’s a mix of SMD and through-hole components on the custom-etched PCB, with a separate riser card to show off the VFDs a little bit through the front panel of the 3D printed case.

All in all, we find this little amp pretty cool, and we love the way it puts a twist on the venerable VFD. We’ve seen similar VFD amps before, but this one’s fit and finish really pays off.

An Affordable And Programmable PLC

December 8, 2022 by 74 Comments

We’re all used to general purpose microcontroller boards such as the Arduino or its many imitators, but perhaps we don’t see as much of their industrial cousins. A programmable logic controller (PLC) is a computer designed to automate industrial machinery, and comes with protected interfaces and usually a specific PLC programming environment. Thus [Galopago]’s work with an inexpensive Chinese PLC clone is especially interesting, providing a route forward to using it within the Arduino IDE ecosystem.

Opening it up, the processor is identified as an STM32F103, and the connection needed to place it in bootloader mode is identified. Then it can be programmed from the Arduino IDE, even though its bootloader can’t be changed. Then to complete the process it’s necessary to identify the various different inputs and outputs by old-fashioned hardware reverse engineering.

This PLC may not be quite as robust as some products costing much more money, but it still represents a cost-effective way to access a microcontroller board with much of the interface circuitry already installed that would normally be required for controlling machinery. We expect that we’ll be seeing it appear on these pages over the coming months, and perhaps there might even be another comparison in the air.

A Wheatstone Bridge Matches Your Pots

December 7, 2022 by 15 Comments

Sometimes the simplest hacks can be the most useful or ingenious, and such is the case with [Keri Szafir]’s method of ensuring that potentiometers used in audio devices are matched. If you consider a typical stereo amplifier for a moment, you’ll see two amplifiers in one box with a single volume control. Two channels, one knob? Volume knobs are ganged stereo potentiometers.

All potentiometers are not created equal, and particularly in the cheaper devices they may not have a consistently matched resistance across both pots and across their travel. This messes up the stereo balance, so naturally it’s worth selecting a part with good matching. [Keri] selects them not with his golden ears, but by wiring both pots together as a Wheatstone bridge. A meter between the two wipers would detect any current due to a mismatch.

A Wheatstone bridge is one of those handy circuits that has plenty of uses in both AC and DC measurements. We probably see them most often in a strain gauge.

A EuroRack synthesizer module with an oscilloscope in the background showing a waveform

Recreating The Sounds Of The ’90s With A YM3812 Synthesizer

December 7, 2022 by 9 Comments

One reason the x86 PC became the dominant game platform in the early 1990s was the availability of affordable sound cards like the AdLib and Sound Blaster. These provided a quantum leap in sound quality compared to the PC speaker’s tinny beeps, thanks to Yamaha’s YM3812 chip, also known as OPL2. [Tyler] has made a detailed study of the various OPL series chips and wrote a comprehensive guide describing their operation.

[Tyler] begins by explaining the theory of FM synthesis. The basic idea is that you generate sine waves of different frequencies, combine them through mixing and modulation, and then adjust their strength over time. This way, a few simple operations on the chip’s nine sound channels can generate an astonishing variety of sounds from clear notes to chaotic noise. He then delves into the details of the YM3812 chip, including its 279 different register settings that enable all these operations.

The final goal of [Tyler]’s research is the design of a YM3812 EuroRack module that fits inside standard modular synthesizers. He’ll go into detail on the board’s design and construction in future blog posts, but he already shows the finished product and demonstrates its features in the video embedded below. It’s a great introduction if you’re new to FM synthesis and want to recreate those magic DOS game sounds.

Of course, you can also just connect the OPL2 chip to your DOS computer, whether through a classic sound card or through a parallel port. The related YM2612 from the Sega Genesis also makes a fine synthesizer.

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A Tiny RISC-V Emulator Runs Linux With No MMU. And Yes, It Runs DOOM!

December 7, 2022 by 28 Comments

It’s something of an article of faith, that to run Linux your computer must include a hardware memory management unit, or MMU. To an extent it’s true, in that for a Linux-based system to shine it must have that hardware, but in fact there has been support for MMU-less Linux for many years now. Prolific hacker [cnlohr] has created an emulated simple RISCV processor without an MMU, and not only does it run Linux, it also runs DOOM.

The videos below the break go into significant depth on writing and debugging an emulator not to mention the inner workings of DOOM, but fear not if it’s not your thing. Everything can be found in a GitHub repository, and there are straightforward instructions should you wish to try it yourself.

All this is entertaining stuff, but it becomes of much more interest when viewed as part of an ongoing chain of projects working on no-MMU Linux for low-end RISC-V microcontrollers. Imagine the prospect of running Linux on a CPU costing relative pennies, and you can see why that’s an interesting prospect. Even if it’s not the most unexpected way to run Linux without an MMU.

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Transparent Metal (Hydroxide) Without Mr. Scott

December 7, 2022 by 24 Comments

There’s a famous scene in one of the Star Trek movies where Scotty, who has traveled to the past, teaches a metal company to create the transparent aluminum he needs to bring some whales back to the future. But [The Action Lab] shows that we already have see-through metal, just not aluminum. You can see a video about why metals are normally opaque.

The metal in question is sodium. Normally, it isn’t transparent, but molten sodium hydroxide does turn transparent after it — well, sort of explodes. Of course, sodium hydroxide isn’t really a metal, but then neither is the aluminum oxide that’s been touted as real transparent aluminum. Aluminum oxide also makes transparent gemstones like rubies. However, there is some — kind of — transparent aluminum at the end of the video.

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