If you’ve ever used an NE602 or similar IC to build a radio, you might have noticed that the datasheet has a “gilbert cell” mixer. What is that? [Electronics for the Inquisitive Experimenter] explains them in a recent video. The gilbert cell is a multiplier, and multiplying two waveforms will work to mix them together.
At the heart of the gilbert cell is essentially three differential amplifiers that share a common current source. The video shows LTSpice simulations of the circuits as he explains them.
Once upon a time, owning a calculator watch was the epitome of cool. Well, for a very specific subset of the population with our own definition of “cool” anyway. The only thing cooler than wearing a calculator watch? Making a calculator watch, of course! If you do it as part of developing your own SDK for a popular RISC V microcontroller, all the better. That’s what [Miroslav Nemecek] did with his Antcalc watch, which is one of the demo projects for the CH32Lib SDK, which is currently under development at version 0.35 as this is written.
It appears as though the solid core wire on the back of the homemade PCB is used to hold the watch band, a nice little hack.
As you might guess, CH32LibSDK is targeting the super-cheap CH32 series of RISC V microcontrollers. Perhaps because the SDK is so early in development, there’s not much documentation outside of the example projects. The examples are all worth looking at, but our tipster wanted us to cover the Antcalc calculator watch specifically.
The Antcalc watch uses the SOP16-packaged CH32V002A4M6 to drive a small OLED display while taking input in Reverse Polish Notation from a dozen small buttons. We’re not sure how the cool kids feel about RPN these days, but that’s got to be worth extra nerd cred. Using a RISC V chip doesn’t hurt in that department, either.
For something so small– 30 mm x 55 mm–it’s looks like a decent little calculator, with 10 registers holding a mantissa of 21 digits and exponents up-to +/-99 in binary coded decimal. Seven layers on the dozen-key input pad mean most of the scientific functions you could ask for are available, along with the ability to record and replay upto 10 macros. There are also ten memory slots, all of which go into the chip’s onboard flash so are non-volatile during a battery swap. (Of which many will be necessary, since this appears to run on a single coin cell.)
When you’re like [Wes] from Watch Wes Work fame, you don’t have a CNC machine hoarding issue, you just have a healthy interest in going down CNC machine repair rabbit holes. Such too was the case with a recently acquired 2001 Milltronics ML15 lathe, that at first glance appeared to be in pristine condition. Yet despite – or because of – living a cushy life at a college’s workshop, it had a number of serious issues, with a busted Z-axis drive board being the first to be tackled.
The Glentek servo board that caused so much grief. (Credit: Watch Wes Work, YouTube)
The identical servo control board next to it worked fine, so it had to be an issue on the board itself. A quick test showed that the H-bridge IGBTs had suffered the typical fate that IGBTs suffer, violently taking out another IC along with them. Enjoyably, this board by one Glentek Inc. did the rebranding thing of components like said IGBTs, which made tracking down suitable replacements an utter pain that was eased only by the desperate communications on forums which provided some clues. Of course, desoldering and testing one of the good IGBTs on the second board showed the exact type of IGBT to get.
After replacing said IGBTs, as well as an optocoupler and other bits and pieces, the servo board was good as new. Next, the CNC lathe also had a busted optical encoder, an unusable tool post and a number of other smaller and larger issues that required addressing. Along the way the term ‘pin-to-pin compatible’ for a replacement driver IC was also found to mean that you still have to read the full datasheet.
Of the whole ordeal, the Glentek servo board definitely caused the most trouble, with the manufacturer providing incomplete schematics, rebranding parts to make generic replacements very hard to find and overall just going for a design that’s interesting but hard to diagnose and fix. To help out anyone else who got cursed with a Glentek servo board like this, [Wes] has made the board files and related info available in a GitHub repository.
It’s likely that Hackaday readers have among them a greater than average number of people who can name one special thing they did on September 23rd, 2002. On that day a new web browser was released, Phoenix version 0.1, and it was a lightweight browser-only derivative of the hugely bloated Mozilla suite. Renamed a few times to become Firefox, it rose to challenge the once-mighty Microsoft Internet Explorer, only to in turn be overtaken by Google’s Chrome.
Now in 2025 it’s a minority browser with an estimated market share just over 2%, and it’s safe to say that Mozilla’s take on AI and the use of advertising data has put them at odds with many of us who’ve kept the faith since that September day 23 years ago. Over the last few months I’ve been actively chasing alternatives, and it’s with sadness that in November 2025, I can finally say I’m Firefox-free.
[Zack], in addition to being a snappy dresser, has a thing for strange 3D printing filament. How strange? Well, in a recent video, he looks at filaments that require 445 C. Even the build plate has to be super hot. He also looks at filament that seems like iron, one that makes you think it is rubber, and a bunch of others.
As you might expect, he’s not using a conventional 3D printer. Although you might be able to get your more conventional printer to handle some of these, especially with some hacking. There is filament with carbon fiber, glass fiber, and more exotic add-ons.
Most of the filaments need special code to get everything working. While you might think you can’t print these engineering filaments, it stands to reason that hobby-grade printers are going to get better over time (as they already have). If the day is coming when folks will be able to print any of these on their out-of-the-box printer, we might as well start researching them now.
If you fancy a drinking game, have a shot every time he changes shots and a double when the Hackaday Prize T-shirt shows up.
If you take a look around you, chances are pretty good that within a few seconds, your eyes will fall on some kind of electrical connector. In this day and age, it’s as likely as not to be a USB connector, given their ubiquity as the charger of choice for everything from phones to flashlights. But there are plenty of other connectors, from mains outlets in the wall to Ethernet connectors, and if you’re anything like us, you’ve got a bench full of DuPonts, banana plugs, BNCs, SMAs, and all the rest of the alphabet soup of connectors.
Given their propensity for failure and their general reputation as a necessary evil in electrical designs, it may seem controversial to say that all connectors are engineered to last. But it’s true; they’re engineered to last, but only for as long as necessary. Some are built for only a few cycles of mating, while others are built for the long haul. Either way, connectors are a great case study in engineering compromise, one that loops physics, chemistry, and materials science into the process.
There’s a tactile joy to the humble 3.5″ floppy that no USB stick will ever match. It’s not just the way they thunk into place in a well-made drive, the eject button, too, is a tactile experience not to be missed. If you were a child in disk-drive days, you may have popped a disk in-and-out repeatedly just for the fun of it — and if you weren’t a child, and did it anyway, we’re not going to judge. [igor] has come up with a physical game called “Floppy Flopper” that provides an excuse to do just that en masse, and it looks like lots of fun.
It consists of nine working floppy drives in a 3×3 grid, all mounted on a hefty welded-steel frame. Each drive has an RGB LED above it. The name of the game is to swap floppies as quickly as possible so that the color of the floppy in the drive matches the color flashing above it. Each successful insertion is worth thirteen points, tracked on a lovely matrix display. Each round is faster than the last, until you miss the window or mix up colors in haste. That might make more sense if you watch the demo video below.
