Day: September 19, 2024

Switching Regulators: Mistake Fixing For Dummies

September 19, 2024 by 31 Comments

Some time ago, while designing the PCB for the Sony Vaio replacement motherboard, I went on a quest to find a perfect 5 V boost regulator. Requirements are simple – output 5 V at about 2A , with input ranging from 3 V to 5 V, and when the input is 5 V, go into “100% duty” (“pass-through”/”bypass”) mode where the output is directly powered from the input, saving me from any conversion inefficiencies for USB port power when a charger is connected. Plus, a single EN pin, no digital configuration, small footprint, no BGA, no unsolicited services or offers – what more could one ask for.

As usual, I go to an online shop, set the parameters: single channel, all topologies that say “boost” in the name, output range, sort by price, download datasheets one by one and see what kind of nice chips I can find. Eventually, I found the holy grail chip for me, the MIC2876, originally from Micrel, now made by Microchip.

MIC2876 is a 5 V regulator with the exact features I describe above – to a T! It also comes with cool features, like a PG “Power good” output, bidirectional load disconnect (voltage applied to output won’t leak into input), EMI reduction and efficiency modes, and it’s decently cheap. I put it on the Sony Vaio board among five other regulators, ordered the board, assembled it, powered it up, and applied a positive logic level onto the regulator’s EN pin.

Immediately, I saw the regulator producing 3 V output accompanied by loud buzzing noise – as opposed to producing 5 V output without any audible noise. Here’s how the regulator ended up failing, how exactly I screwed up the design, and how I’m creating a mod board to fix it – so that the boards I meticulously assembled, don’t go to waste.

Some Background… Noise

Continue reading “Switching Regulators: Mistake Fixing For Dummies” →

Mothbox Watches Bugs, So You — Or Your Grad Students — Don’t Have To

September 19, 2024 by 8 Comments

To the extent that one has strong feelings about insects, they tend toward the extremes of a spectrum that runs from a complete fascination with their diversity and the specializations they’ve evolved to exploit unique and ultra-narrow ecological niches, and “Eww, ick! Kill it!” It’s pretty clear that [Dr. Andy Quitmeyer] and his team tend toward the former, and while they love their bugs, spending all night watching them is a tough enough gig that they came up with Mothbox, the automated insect monitor.

Insect censuses are valuable tools for assessing the state of an ecosystem, especially insects’ vast numbers, short lifespan, and proximity to the base of the food chain. Mothbox is designed to be deployed in insect-rich environments and automatically recognize and tally the moths it sees. It uses an Arducam and Raspberry Pi for image capture, plus an array of UV and visible LEDs, all in a weatherproof enclosure. The moths are attracted to the light and fly between the camera and a plain white background, where an image is captured. YOLO v8 locates all the moths in the image, crops them out, and sends them to BioCLIP, a vision model for organismal biology that appears similar to something we’ve seen before. The model automatically sorts the moths by taxonomic features and keeps a running tally of which species it sees.

Mothbox is open source and the site has a ton of build information if you’re keen to start bug hunting, plus plenty of pictures of actual deployments, which should serve as nightmare fuel to the insectophobes out there.

A Guide To Laser Cutting Metal, If You’ve Got The Cash

September 19, 2024 by 9 Comments

While many of us now have laser cutters — either a K40-style machine or one of the newer high-output diodes — you probably don’t have one that cuts metal. True, some hobby lasers now offer IR laser heads with modest power to engrave metal. The xTool S1, for example, accepts a 2 W IR laser as an option, but we doubt it would cut through anything thicker than foil. However, there are a growing number of fiber and carbon dioxide lasers that can cut metal at semi-reasonable prices, and [All3DP] has a primer on the technology that is worth a read.

According to the post, CO2 lasers are less expensive but require gas assist, can’t work with shiny metals well, and are finicky because of the mirrors and glass tube inside. Fiber lasers cost more, but don’t need gas, work on more materials, and have fewer parts that need maintenance or may be prone to damage. There are other kinds of lasers, but the post focuses on these, the most common ones.

Machines that can cut metal aren’t cheap. They start at about $10,000. However, prices are dropping and we remember when $10,000 would buy you what would today be a terrible oscilloscope, so maybe there’s hope for an impulse-buy metal-cutting laser one day.

It isn’t that diode lasers can’t cut metal at all, but the results are not terribly useful. What would you rather have? A metal cutter or a metal 3D printer?