Nixie Tube RPN Calculator Project

November 7, 2023 by 12 Comments

If you like Nixie tubes and/or DIY calculators, checkout this interesting talk from the HP Handheld Conference in Orlando last month by [Eric Smith] from Brouhaha and [John Doran] from Time Fracture. For 20-some years, [Eric] and the late [Richard Ottosen] have been incrementally developing various DIY calculators — this paper from the 2005 HHC conference is an excellent overview of the early project. [John] got one of those early DIY calculators and set about modifying it to use Nixie tubes. However, he got distracted by other things and set it aside — until reviving it earlier this year and enlisting [Eric]’s aid.

This presentation goes over the hardware aspects of the design. Unlike the earlier PIC-based DIY calculators, they decided to use a WCH RISC-V processor this time around. The calculator’s architecture is intentionally modular, with the display and keyboard housed in completely separate enclosures communicating by a serial interface. If the bulkiness alone doesn’t exclude it from being pocket-sized, the 170 VDC power supply and 1/2 W per digit power consumption certainly does. This modularity does lend itself to DIYers replacing the display, or the keyboard, with something different. [Eric] wants to build a mechanical flip-digit display for his unit. As for the software, [Eric] reviews the firmware approach and some future upgrades, such as making it programmable and emulating other flavors of HP calculators.

If you’re embarking on a similar project yourself, check out this talk and take notes — there are a lot of interesting tidbits on using Nixie tubes in the 21st century. If [Eric]’s name sounds familiar, you may know him from the Nonpareil calculator software used on many emulators and DIY calculator projects, one of which we covered some years ago. [John] is also a long-time tinkerer, and we wrote about his gorgeous D16/M HCMOS computer system back in 2012. Thanks to [Stephen Walters] for sending in the tip.

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Browsing The WWW On A 1980s IBM PC Using MicroWeb

November 6, 2023 by 13 Comments

Do you ever sit at your 1981 vintage IBM PC and get the urge to pop onto that newfangled ‘WWW’ to stay up to date on all the goings-on in the world? Fret not, because [Al’s Geek Lab] has you covered with a new video (also embedded below), which you will unfortunately have to watch on a device that was made at the very least in the late 1990s. What makes this feat possible is a miniscule web browser called MicroWeb, created by [jhhoward], that will happily run on an 8088 CPU or compatible, without requiring any fiddling with EMS or similar RAM extensions.

Of course, you do need to have some kind of way to actually connect to the World Wide Web, which can be an ISA network expansion card, EtherSlip, as well as using a thin client as a network bridge with some Serial Line Interface Protocol (SLIP) action. Of course, some limitations exist, in that graphics and CSS are not rendered, JavaScript is totally off-limits, and for HTTPS-only websites a workaround like retro-proxy has to be used as TLS encryption would be completely unusable on a couple-of-MHz-CPU.

There’s also the FrogFind service, which will helpfully strip down a target website down to its barest HTML essentials, along with the 68K News site that strips down Google News, so that you can enjoy the WWW in its text-based glory as it would have looked in the early 1980s.

(Thanks to [Stephen Walters] for the tip)

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Tiny Forth Could Be The Smallest

November 6, 2023 by 29 Comments

When you think of a programming language, you probably think of a hefty compiler or interpreter. Maybe its on a bunch of floppies, a CD, or even an EEPROM. But what about a language that fits in a single disk sector? A language like that would — in theory — be used to help bootstrap a computer system and that was the idea behind Sector Forth and, later, Sector Lisp. However, there’s a new game in town: milliForth, which claims to be the smallest ever at 422 380 bytes.

Why would you want such a thing? Well, first of all, why not? Even as a form of code golf, packing a functioning language into a tiny space seems interesting. However, you could also presumably use something like this to boot a small system or on a system with limited storage.

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3D-Printed LED Wall Clock Does Lots With Little

November 6, 2023 by 14 Comments

This wall clock built by [Alf Müller] is lovely, using two NeoPixel rings to mark the time by casting light onto a 3D-printed ring. The blue shows the minutes, made more discrete by a grid inside the ring. The green shows the hours.  [Alf] has provided the code so you can rework the color scheme.  It might be interesting to add seconds with the red LEDs, or perhaps a countdown triggered by a touch sensor…

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An ebike motor with the controller cover removed. A number of wires and connectors take up most of the space in the cavity.

Open Brain Surgery For EBikes And EScooters

November 6, 2023 by 7 Comments

Personal Electric Vehicles (PEVs) all contain the same basic set of parts: a motor, a battery, a motor controller, some sensors, and a display to parse the information. This simplicity allowed [casainho] to develop a custom controller setup for their own PEVs.

Built around the venerable VESC motor controller, [casainho]’s addition is the EBike/EScooter board that interfaces the existing motor of a device to the controller. Their ESP32-powered CircuitPython solution takes the sensor output of a given bike or scooter (throttle, cadence, or torque) and translates it into the inputs the controller uses to set the motor power.

They’ve also designed an ESP32-based display to interface the rest of the system to the user while riding. Since it also runs CircuitPython, it’s easy to reconfigure the functions of the three button device to display whatever you’d like as well as change various drive modes of your system. I know I’d love to see my own ebikes have a different mode for riding on road versus on shared paths since not getting run over by cars and not harassing pedestrians aren’t going to have the same power profile.

If you want to find more ways to join the PEV revolution, check out this wild omni-wheeled bike or this solar car built from two separate e-bikes. If that doesn’t suit your fancy, how about an off-label use for an e-bike battery to power your laptop off grid?

3D printed ring with 4-integrated electrodes for measuring bioimpedance for measuring blood pressure from the finger

Smart Ring Measures Blood Pressure

November 6, 2023 by 17 Comments

Continuous blood pressure monitoring has always been a major challenge for the biohacking community. Those giant arm cuffs aren’t exactly the kind of thing you want to wear all day and the wrist monitors aren’t super great either. So, [Kaan] and his research team set out to create a better continuous blood pressure monitor. This time as a ring.

When your heart beats, the volume of blood in the blood vessels increases ever so slightly. This increase in volume results in a decrease in electrical impedance because blood is fairly conductive. We’ve seen a similar volume measurement using light for detecting heart rate, but [Kaan] says with impedance, you won’t need to worry about the effect of skin tone on the accuracy of the measurement.

As far as the hardware is concerned, they inject a small, constant 10 kHz sinusoidal current into the finger through 2 current-injecting electrodes, and then measure the resulting voltage drop across the finger with two sensing electrodes, a standard 4-probe Kelvin approach. Their results seem pretty good. They are within 5.27 millimeters of mercury (mmHg) of the gold standard for systolic blood pressure and 3.87 mmHg for diastolic blood pressure across 10 subjects, which they say are within the American Association for the Advancement of Medical Instrumentation’s (AAMI) guidelines. That’s definitely something to catch your attention.

We’ve seen several attempts to measure blood pressure using the analogous photoplethysmography technique, but those generally don’t seem to work out. Will the impedance plethysmography approach overcome the optical technique’s shortcomings? Only time will tell.

Virginia To Get Large-Scale Wind Farm

November 6, 2023 by 89 Comments

If you go about 27 miles off the coast of Virginia, you’ll find two windmills jutting up out of the sea. Two windmills aren’t particularly interesting until you realize that these two are on the edge of a 2,100-acre lease that Dominion Energy is placing in Federal water. According to the company, those two will be joined by 176 more windmills on a nearly 113,000-acre adjacent lease. The project has been in the planning and pilot phase for a while, but it was recently given the green light by the US government. You can see a promotional video about the project below. There’s also a video of the first monopiles — the mounts for the windmills — arriving in the area.

The project will eventually have three offshore substations that feed the power to the state military reservation and, from there, to Naval Air Station Oceania, where it feeds the commercial power grid. The final project will power 660,000 homes.

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