Is It Time To Retire The TP4056?

August 8, 2025 by Tyler August 30 Comments

The TP4056 is the default charge-controller chip for any maker or hacker working with lithium batteries. And why not? You can get perfectly-functional knockoffs on handy breakout boards from the usual online sources for pennies. Betteridge’s Law aside, [Lefty Maker] thinks that it may well be time to move on from the TP4056 and spends his latest video telling us why, along with promoting an alternative.

His part of choice is another TI chip, the BQ25185. [Lefty] put together his own charge controller board to show off the capabilities of this chip — including variable under- and over-charge protection voltages. Much of his beef with the TP4056 has less to do with that chip than with the cheap charge modules it comes on: when he crows about the lack of mounting holes and proper USB-PD on the knock-off modules, it occurs to us he could have had those features on his board even if he’d used a TP4056.

On the other hand, the flexibility offered by the BQ25185 is great to future-proof projects in case the dominant battery chemistry changes, or you just change your mind about what sort of battery you want to use. Sure, you’d need to swap a few resistors to set new trigger voltages and charging current, but that beats starting from scratch.

[Lefty Maker] also points out some of the advantages to making your own boards rather than relying on cheap modules. Namely, you can make them however you want. From a longer USB port to indicator LEDs and a built-in battery compartment, this charging board is exactly what [Lefty Maker] wants. Given how cheap custom PCBs are these days, it’s not hard to justify rolling your own.

The same cannot be said of genuine TI silicon, however. While the BQ25185 has a few good features that [Lefty Maker] points out in the video, we’re not sure the added price is worth it. Sure, it’s only a couple bucks, but that’s more than a 300% increase!

We’ve seen other projects pushing alternative charge controllers, but for now the TP4056 reigns as the easy option.

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Can A Thermal Printer Cure ADHD?

August 6, 2025 by Tyler August 34 Comments

No, of course not. Per Betteridge’s law, that’s the answer to any headline with a question mark. On the other hand, while a thermal printer might not cure ADHD, it can help treat it — according to [Laurie Hérault], to the point of curing his procrastination habit. Even if you don’t have ADHD, you probably do procrastinate sometimes, so this hack is worth a look.

The printer itself is a key hardware portion of the hack, but the hack itself is purely organizational. [Laurie] started with post-its before adding automation. Before the post-it notes came a simple realization: [Laurie] could sit and play games for hours, but not buckle down for serious work for more than a few minutes, if he could even get started. (Who can’t relate?) That sent him down a rabbit hole reading about the psychology of what makes games so addictive — and the idea of “gamification” that was so popular in educational circles not long ago.

Unlike work, games give you a loop of unambiguous, instant, and continuous feedback to pump your dopamine circuits. [Laurie] uses the example of an FPS. You aim, you shoot — and either you miss, or you hit the target. Either way, there’s feedback. When you hit, your brain gives you dopamine. This fast loop of input -> feedback is what [Laurie] felt he was missing from his day.

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2025 One Hertz Challenge: Shoulda Put A Ring Oscillator On It

August 5, 2025 by Tyler August 12 Comments

Entries keep ticking in for the One Hertz Challenge, some more practical than others. [Pierre-Loup M.]’s One Hertz Sculpture has no pretensions of being anything but pretty, but we can absolutely respect the artistic impulse behind it.

The sculpture is a free-form circuit inside of a picture frame. There are 9 LEDs in a ring with a few other components to produce a reverse-chase effect (one going dark at a time) taking about 1 second to circle the sculpture. As far as free-form circuit art goes, it’s handsomely done, but as this is Hackaday it’s probably the electronics, rather that the aesthetics that are of interest.

The circuit is an example of a ring oscillator: a cascading chain of NOT gates, endlessly feeding into and inverting one

An animated gif of the sculpture at work — Without timing it, it looks like 1 Hz, even if we know it’s not.

another. The NOT gates are implemented in resistor-transistor logic with 2N3904 NPN transistors, nine in total. Of course the inverter delay of this sort of handmade logic gate is far too fast for an aesthetically pleasing (or visible) chase, so some extra circuitry is needed to slow down the oscillations to something less than the 5 MHz it would naturally do. This is affected by pairing every transistor with an RC oscillator. Ideally the RC oscillator would have a 0.111..s period (1/9th of a second), but a few things got in the way of that. The RC oscillator isn’t oscillating in a vacuum, and interactions with the rest of the circuit have it running just a little bit fast. That’s really of no matter; a simple oscillator circuit like this wasn’t going to be a shoe in for the accuracy-based Time Lords category of this contest. As a sculpture and not a clock, you’re not going to notice it isn’t running at exactly 1Hz. (Though a ring-oscillator based clock would be a sight indeed.)

We’ve seen ring oscillators before, including inside the venerable 8087 coprocessor and this delightfully romantic beating-heart gift, but this is the first one that seems to have entered the One Hertz Challenge.

If you have a hankering for hertz, the contest is still open, but you’d better get ticking! The contest closes August 19th.

Flex PCB Underlies The Watch Of The Future

August 5, 2025 by Tyler August 8 Comments

If you were at OpenSauce, you may have seen new Youtuber [Sahko] waltzing about with a retrofuturistic peice of jewelery that revealed itself as a very cool watch. If you weren’t, he’s his very first video on YouTube detailing the design and construction of this piece. We’ve embedded it below, and it’s worth a watch. (Pun intended, as always.)

The build was inspired by the delightful amber LED dot-matrix display modules that circle the band of the watch. They go by HCMS2901, but [Sahko] recommends using the HCMS3901 as it’s both more 3.3V-tolerant and easier to find now. A challenge in mounting so many displays was the voltage on the supply rail dropping below the logic level; presumably the newer version does not have this problem to the same degree. Either way we love the look of these little displays and are pondering projects of our own that might include them.

He’s got quite a few wrapped around his wrist, so at full brightness, all these displays draw one amp. That explains why like the LED watches of the 1970s, the default state of the displays is “OFF”. Even with a LiPo pouch salvaged from a disposable vape, the runtime would only be half an hour at full brightness without that periodicity. Luckily [Sahko] included buttons on the band of the watch to activate it and control the brightness so it isn’t always blasting at full. There are also different modes available, including a really cool waterfall effect you can see in the video.

The band is an interesting choice, too: it’s just a flex PCB. There’s nothing backing it, aside from its own stiffeners, which makes us very curious how well this watch would hold up to daily use. There’s no clasp in the traditional sense, either: the band is closed by a 4-pin connector that doubles as both charge and the USB programmer for the stm32u08 microcontroller that runs the displays. Conveniently for a watch, this version of the stm32 has an RTC, so it keeps time as well. We dig the minimalism of this design; it’s a great contrast to the maximalism of wrapping your wrist in displays.

We’ve seen very similar displays on an edge-viewed watch, but a tiny amber LED matrix never gets old. If you wrapping your wrist in all those tiny LEDs is too impractically power-hungry, try using Nixie tubes.

We’re always watching for projects– wrist mounted clocks or otherwise– so if you’ve got the time, please drop us a tip.

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Open Source 5-Axis Printer Has Its Own Slicer

August 4, 2025 by Tyler August 22 Comments

Three-axis 3D printing has been with us long enough that everybody knows the limitations, but so far, adding extra axes has been very much a niche endeavor. [Daniel] at Fractal Robotics wants to change that, with the Fractal 5 Pro 5-axis printer, and its corresponding Fractal Cortex slicer.

The printer looks like an extra-beefy Voron from a distance, which is no surprise as [Daniel] admits to taking heavy inspiration from the Voron Trident. The Fractal 5 shares a core-XY geometry with the Voron, using beefy 30 mm x 30 mm extrusions. Also like the Voron, it runs Klipper on a Raspberry Pi hiding in the base. Under a standard-looking printhead using a BondTech extruder and E3D volcano hotend, we find the extra two axes hiding under the circular build plate. The B axis is a gantry that can pivot the build plate assembly a full 90 degrees; the A axis spins the plate without limit thanks to the slip rings built into the design.

The extruder may look fairly normal, but it has actually been designed very carefully to allow the nozzle to get as close as possible to the build plate when the B-axis is at 90 degrees. It looks like the E3D hotend is actually the limiting factor there, which gives plenty of design freedom when planning prints in the accompanying Fractal Cortex slicer.

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Rebuilt Batteries For The Cutest Clamshell At The Cafe

August 3, 2025 by Tyler August 22 Comments

Keeping retrocomputers going can be tricky enough, but when you’re talking retro laptops, the battery packs add an extra challenge. While one could simply live without the battery, that’s not going to give you the full retro experience. Replacement batteries are long out of stock, so what can one do? Well, one can check out this excellent tutorial by [lazd] on rebuilding an iBook G3 Clamshell battery.

Even if you don’t have this particular laptop, the general process is likely to be similar for PC laptops of similar vintage. (Which we still can’t believe is a whole quarter-century ago.) Luckily for retrocomputer enthusiasts, even Apple used standard 18650 cells in those bygone, halcyon days when computers were allowed to be more than a few atoms thick. They do need to be unprotected, flat-top cells, but that’s easy enough to source.

So it’s really a matter of carefully prying apart the casing (apparently it needs to be Apple-branded; aftermarket cases can’t survive being opened), removing the old batteries, and welding nickel tabs onto the new cells in the proper configuration. One thing that surprised us is that, apparently, Apple did not go in for balancing in those days — so make sure your cells are all in perfect condition and all equally charged before you start, or things won’t end nicely.

As always, battery orientation matters! The cells are welded into two sets in this Clamshell iBook battery.

Assuming you can pull it off (and your battery pack’s control chip has lasted the 300 moons since its manufacture), you’ll get a not-insignificant 5-hour battery run out of what’s sure to be the cutest clamshell computer at the cafe.

If you are repairing an iBook, while you’re at it, why not upgrade the RAM? You might even be able to fix the screen if it’s succumbing to the sadly-too-common vinegar syndrome.

2025 One Hertz Challenge: Learn Morse Code One Second At A Time

August 2, 2025 by Tyler August 3 Comments

Learning Morse Code is no longer a requirement for HAMs in many jurisdictions, but it’s still a nice skill to have. [I_void(warranties)] wanted to learn, but couldn’t find a trainer that fit his style. What to do but build it yourself? Since we’re in the midst of a challenge, he took up the gauntlet and turned his need to learn Morse into a 1 hertz Morse code game.

In concept it is quite simple: a message beeps out in Morse, with a corresponding LED flash, all in one second. The player then has one second to type think they heard. Get it done fast enough, and a character LCD will tell you if you scored.

The project is based around an Arduino Nano; thanks to easily-available libraries, a PS/2 keyboard can serve as input and a 2×16 LCD as feedback with no real effort expended. For the audible component of the Morse challenge, an 8-ohm speaker is driven right off a pin on the Arduino. We won’t claim this efficient design only took one second to put together, but it probably didn’t take too long.

Of course this trainer, unlike some we’ve seen, only helps you learn to listen to the stream of dots and dashes. None of the others ever tried to fit a One Hertz theme, or [I_void(warranties)]’s particular learning style. For some, decoupling send and receive might be just the ticket to finally learning Morse one second at a time.