Turning A Bluetooth Caliper Into A FreeCAD Input Device

April 5, 2026 by Maya Posch 22 Comments

It’s a common ritual: whipping out those calipers or similar measuring devices to measure part of a physical object that we’re trying to transfer into a digital model in an application like FreeCAD. Wouldn’t it be nice if said measurements were to be transferred instantaneously into the model’s sketch, including appropriate units of measurement? That’s essentially what [stv0g] has done by merging a Sylvac Bluetooth-enabled caliper and FreeCAD using a plugin.

Key to the whole operation is a Bluetooth-enabled caliper like the Sylvac S_Cal EVO that [stv0g] managed to score on EBay for a mere €90 when it normally goes for multiple times that amount. This has BLE built in, using BLE’s standard GATT profiles for device communications specifications. Along with the provided Sylvac developer tools, this made it relatively easy to develop the InstrumentInput addon for FreeCAD.

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Tracking Parts Box Usage With Stickers

April 4, 2026 by Maya Posch 18 Comments

Many of us are guilty of toeing the line between having a ready supply of components at hand and simply hoarding for fear of throwing anything out. In a first admission of this problem, [Scott Lawson] decided to implement a couple of changes to assess his own position on this sliding scale.

The first change was to only put parts, components, and supplies in transparent boxes. Next was to add a sticker on each box noting the contents and box creation date. This was extended to plastic bags inside the boxes when further subdivision was warranted.

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Exposing A Radiation-Hardened 2.4 GHz Wi-Fi Receiver To 500 Kilograys

April 4, 2026 by Maya Posch 5 Comments

From outer space to down here on Earth, there are many places where ionizing radiation levels are high enough that they effectively bar access for humans, but also make life miserable for anything containing semiconductor technology. This is especially true for anything involving wireless communications, such as Wi-Fi. However, recently Japanese researchers have created a Wi-Fi chip that is claimed to be so radiation-hardened that it can be used even in gamma ray-rich environments, such as in the worst contaminated depths of the Fukushima Daiichi nuclear reactor.

The indicated dose exposure of 500 kilograys that the chip survived during testing is quite significant. A single gray (Gy) is the absorption of one joule of energy per kilogram of matter. In radiation therapy, a solid epithelial tumor can receive as much as 60 to 80 Gy in a single dose, for example.

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Reverse-Engineering A Handheld Car Tire Pressure Gauge

April 3, 2026 by Maya Posch 6 Comments

The SDIC 8-bit MCU. (Credit: electronupdate, YouTube)

In this wonderful world of MEMS technology, sensor technology has been downsized and reduced in cost to the point where you can buy a car tire pressure sensor for less than $3 USD on a site like AliExpress. Recently [electronupdate] got his mittens on one of these items to take a look inside, and compare it against his trusty old mechanical tire pressure gauge.

Perhaps unsurprisingly, there isn’t a whole lot inside these devices once you pop them open to reveal the PCB. The MEMS device is a tiny device at the top, which has the pressurized air from the tire guided to it. The small hole inside the metal can leads to the internals that consist of a thin diaphragm with four piezoresistors that enable measurements on said diaphragm from which pressure can be determined.

Handling these measurements and displaying results on the small zebra connector-connected LCD is an 8-bit MCU manufactured by Chinese company SDIC. Although the part number on the die doesn’t lead to any specific part on the SDIC site, similar SDIC parts have about 256 bytes of SRAM and a few kB of one-time programmable ROM.

This MCU also integrates the clock oscillator, thus requiring virtually no external parts to work. Finally, its sigma-delta ADC interacts with the MEMS device, rounding out a very simple device that’s nevertheless more than accurate enough for a spot check as well as quite portable.

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Fixing An E-Waste ASUS P5A-B Socket 7 Mainboard

April 3, 2026 by Maya Posch 9 Comments

A fun part of retro computing is saving ‘e-waste’ that was headed for certain destruction. These boards can have any number of defects, modifications and more that have to be remedied prior to using them. In the case of the Asus P5A-B Socket 7 mainboard that [Bits und Bolts] rescued from the scrapheap at least one issue was obvious: someone had ripped off the plastic part of the ZIF socket, leaving only the metal pins poking out like an awkward kind of LGA socket.

In addition to the busted PGA ZIF socket there was additional damage, including a broken SMT capacitor and missing resistor. Interestingly, someone had apparently modded the ATX power connector to permanently power on the system by removing a pin and bridging to the power-on signal. Obviously this mod had to be undone by removing the bridge and installing a new pin. After this cracked solder joints had to be addressed, before the tedious task of removing the stray PGA socket pins one by one started.

Exactly what was done to this mainboard and why will likely forever remain a mystery, but at least there didn’t seem to be any serious damage. After installing a CPU it was possible to boot and access the BIOS as well as run a couple of tools, confirming that one more Socket 7 board has been saved from the scrapper.

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Addressing The Divisive Topic That Is Boiling Water

April 2, 2026 by Maya Posch 29 Comments

The topic of boiling water is apparently a rather divisive topic, with plenty of strong opinions to go around on what is safe and the most efficient way to go about it. Thus in a new video [Cahn] sought to address the many comments that came in after his previous testing of electric kettles on either 12 VDC or 240 VAC.

What’s interesting about this whole topic is that at its core the overall efficiency of boiling water is simply a matter of calculating the energy input minus energy losses, with the remaining energy going into the water.

As we can see in the video, using a higher battery voltage doesn’t really change the efficiency of a 12 VDC kettle, but the higher current draw does manage to melt a fuse that can’t take the heat — requiring a 20 amp fuse instead of the 15 A one.

One change that does make a difference is how it’s connected. Replacing the thin gauge wiring and the attached cigarette lighter plug on the 12 VDC kettle with beefier cable and an Anderson plug made things run cooler, resulting in an efficiency bump of about 10%. This cut the time required to get the water boiling by around 6 minutes.

Added to this test were an induction hob and an iso-butane-powered Jetboil, both of which scored rather unimpressively. For the induction option it’s obvious that a lot of energy is wasted by having the pan radiate it away from the water, while burning iso-butane loses energy through the exhaust gases. Ultimately what you pick to boil water with should thus be mostly determined by convenience rather than sheer physics.

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The Raspberry Pi 4 With 3 GB RAM Is No Joke

April 2, 2026 by Maya Posch 62 Comments

Raspberry Pi 5 price increases. (Credit: Jeff Geerling)

Although easily dismissed by some as another cruel April Fools joke, Raspberry Pi’s announcement of a new 3 GB model of the Raspberry Pi 4 along with (more) price increases for other models was no joke. Courtesy of the ongoing RAMpocalypse, supplies of LPDDR4 and LPDDR5 are massively affected, leading to this new RPi 4 model with two 1.5 GB LPDDR4 chips, as these are apparently cheaper to source.

Affected in this latest price increase across RP’s product range are RPi 4 and 5 models with 4 or more GB of RAM, with price bumps ranging from $25 on the low end to $150 for the Raspberry Pi 500+. If you wanted a Raspberry Pi 5 with 16 GB of RAM, you’re now paying $300 for the privilege.

Obviously, this news has got people like [Jeff Geerling] rather down in the dumps, essentially stating that using SBCs like the RPi is now beyond the means of many hobbyists. While you can still use SBCs that use e.g. LPDDR2 RAM, such as the older RPi Zero, 2 and 3 models, [Jeff] himself is now moving more towards wrangling with snakes on MCUs, as these boards are so far not significantly affected in terms of price.

With current projections in the RAM market being that this year will still see more price increases, it remains hard to tell exactly how ‘temporary’ this situation will be. That said, using readily available, powerful and cheap MCUs like the ESP32 variants for projects isn’t a bad idea if you really don’t need to be running more than perhaps FreeRTOS.

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