The Many Questions and Challenges with DIY Hydroelectric Generators

The concept of building your own hydroelectric generator seems simple at face value: use gravity to impart as much force as possible onto a turbine, which spins a generator, thus generating electricity. If you’re like the bloke over at [FarmCraft101] trying to DIY this with your farm pond and a lot of PVC pipes, you may have some significantly more in-depth questions, especially pertaining to what kind of generator to use. This and other questions, some of which were raised after the previous video in which the first prototype generator was assembled, are answered in this follow-up video.

When you DIY such a hydroelectric system, you have a number of options when it comes to just the turbine design alone, with the Kaplan-style turbine being one of the most straightforward ones – especially if you use a fixed pitch instead of adjustable – but you can go pretty far in the weeds with alternatives. As for the sharp drop-off after the turbine in the used design, the technical term is a draft tube, which is actually more efficient in this kind of low head, high flow hydroelectric dam situation.

After getting his money back for the unusable ‘3 kW’ generator, there were three options left: try an EBay special, get a purpose-built one from a US company, or rewind an alternator stator for higher voltage output than the standard 12/24V. Ultimately option four was chosen, as in ‘all of the above’, so that comparison is coming up in a future video.

There were also questions from viewers about why he opted to rectify the AC power from the generator and use DC transmission to the nearest farm building. The main reason is efficiency, as DC transmission lines lack the skin effect losses. The other is that the grid-tie inverter that he plans to use needs DC input anyway. Not having to deal with AC transmission issues like losses and reactive power shenanigans is a major plus here.

Once the three new generator versions are being tested it will be interesting to see how they perform. One thing with the Kaplan-style turbine is that too fast RPM induces cavitation, which will erode the propeller pretty quickly. Generally car alternators require a pretty fast RPM, so that may not work out too well. There is also the question of the DC voltage generated, as for DC transmission you want to have as high a voltage as possible to reduce the current.

The purpose-built generator he purchased tops out at 48V, which is quite low. The goal is to have at least 230 VAC before rectification, so a step-up transformer may be needed. Unfortunately three-phase transformers are pretty pricy again, making the rewound alternator seem less crazy. The wild card here is perhaps whether the EBay-purchased generator is a diamond in the rough and works out of the box as hoped.

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hackaday.com/2026/01/06/the-ma…

Tired of Burnt Fingers? Try PID Tuning the Hot Glue Gun

Hot glue guns are pretty simple beasts: there’s an on/off switch, a heating element, and a source of current, be it battery or wired. You turn it on, and the heater starts warming up; eventually you can start extruding the thermoplastic sticks we call “hot glue”. Since there’s no temperature control, the longer you run the gun, the warmer it gets until it is inevitably hotter than you actually want– either burning you or oozing thermoplastic out the tip. [Mellow_Labs] was sick of that after a marathon hot-glue session, and decided to improve on his hot glue gun with PID tuning in the video embedded below.

PID tuning is probably a familiar concept to most of you, particularly those who have 3D printers, where it’s used in exactly the same way [Mellow_Labs] puts it to work in the hot glue gun. By varying the input (in this case the power to the heater) proportional both to the Parameter (in this case, temperature) as well as the Integral and Derivative of that value, you can have a much steadier control than more naive algorithms, like the simple “on/off” thermostat that leads to large temperature swings.

In this case [Mellow_Labs] is implementing the PID control using a thermistor that looks like it came from a 3D printer, and a MOSFET driven by an RP2040. Microcontroller gets its power via the hot glue gun’s battery fed through a buck converter. Since he has them, a small OLED screen displays temperature, which is set with a pair of push-buttons. Thus, one can set a temperature hot enough to melt the glue, but low enough to avoid oozing or third degree burns.

He does not share the code he’s running on the RP2040, but if you are inspired to replicate this project and don’t want to roll your own, there are plenty of example PID scripts out there, like the one in this lovely robot. No, PID isn’t reserved for thermostats– but if you are controlling heat, it’s not reserved for electric, either. Some intrepid soul put built a PID controller for a charcoal BBQ once.

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hackaday.com/2026/01/06/tired-…

PiStorm68K Offers Supercharged Retro Amiga Experience

[AmiCube] has announced their new PiStorm68K special edition MiniMig accelerator board. This board was developed to replace the 68000 CPU in a MiniMig — a recreation of the original Amiga chipset in an FPGA allowing a real genuine 68000 CPU to operate.

The PiStorm68K itself can host a real genuine 68000 CPU but it can also host various Raspberry Pi models which can do emulation of a 68000. So if you combine a PiStorm68K with a MiniMig you can, at your option, boot into an emulated environment with massively increased performance, or you can boot into an original environment, with its reliable and charming sluggishness.

In the introduction video below, [AmiCube] uses the SYSINFO utility software to compare the CPU speed when using emulation (1531 MIPS) versus the original (4.47 MIPS), where MIPS means Millions of Instructions Per Second. As you can see the 68000 emulated by the Raspberry Pi is way faster than the original. The Raspberry Pi also emulates a floating-point unit (FPU) which the original doesn’t include and a memory management unit (MMU) which isn’t used.

If you’re interested in old Amiga tech you might also like to read about Chip Swap Fixes A Dead Amiga 600 or The Many-Sprites Interpretation Of Amiga Mechanics.

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hackaday.com/2026/01/06/pistor…

Linux Fu: Yet Another Shell Script Trick

I’m going to go ahead and admit it: I really have too many tray icons. You know the ones. They sit on your taskbar, perhaps doing something in the background or, at least, giving you fingertip access to some service. You’d think that creating a custom tray icon would be hard, but on Linux, it can be surprisingly simple. Part of the reason is that the Freedesktop people created standards, so you don’t typically have to worry about how it works on KDE vs. GNOME or any of the other desktop environments. That’s a big win.

In fact, it is simple enough that you can even make your own tray icons with a lowly shell script. Well, of course, like most interesting shell scripts, you need some helper programs and, in this case, we’ll use YAD — which is “yet another dialog,” a derivative of Zenity. It’s a GTK program that may cause minor issues if you primarily use KDE, but they are nothing insurmountable.

The program is somewhat of a Swiss army knife. You can use it to make dialogs, file pickers, color selectors, printer dialogs, and even — in some versions — simple web browsers. We’ve seen plenty of tools to make pretty scripts, of course. However, the ability to quickly make good-looking taskbar icons is a big win compared to many other tools.

Docs

Depending on what you want to do, YAD will read things from a command line, a file, or standard input. There are dozens of options, and it is, honestly, fairly confusing. Luckily, [Ingemar Karlsson] wrote the Yad Guide, which is very digestible and full of examples.

Exactly what you need will depend on what you want to do. In my case, I want a tray icon that picks up the latest posts from my favorite website. You know. Hackaday?

The Web Connection

YAD can render HTML using WebKit. However, I ran into immediate problems. The version in the repos for the Linux I use was too old to include the HTML option. I found a supposedly statically linked version, but it was missing dependencies. Even after I fixed that, the program still reported errors related to the NVIDIA OpenGL stack.

I quickly abandoned the idea of using a web browser. I turned to two other YAD features. First, the basic dialog can hold text and, in most cases, renders quasi-HTML because it uses the Pango library. However, there is also a text-info dialog built in. Unlike most other YAD features, the text-info dialog reads its input from standard input. However, it doesn’t render markup.

In the end, I decided to try them both. Why not? It is simple enough. But first, I needed a tray icon.

The Tray

YAD can provide a “notification,” which is what it calls a tray icon. You can specify an icon, some text, and a right-click context menu. In addition, it can react when someone clicks on the icon.
Can you find the tray icon we’re talking about?
I decided to write a script with multiple personalities. If you run it with no arguments, it sets up the tray icon. If you pass anything to it, it will show a dialog with the latest Hackaday articles from the RSS feed. I wanted to make those links clickable, and that turned out to be a bit of a wrinkle. Both versions will do the job, but they each need a different approach, as you will see.

Here’s the tray code:

yad --notification --image="$0.icon.png" --text="Hackaday Now" \
--menu="Quit!quit!gtk-quit" --command="$0 show" --no-middle

You can probably guess at most of this without the manual. The image is stored in a file with the same name as the script, but with .icon.png at the end. That’s the icon in the tray. The simple menu provides an option to exit the program. If you click the icon, it calls the same script again, but with the “show” argument. The script doesn’t care what the argument is, but maybe one day it will.

So that part of the project was extremely simple. The next job is making the dialog appear.

Text Info

Grabbing the RSS feed with wget is trivial. You could use grep, sed, and bash pattern replacement to extract the titles and URLs, but I opted for awk and a brute-force parsing approach.
This works, but the URLs are long and not terribly attractive. The list is scrollable, and there are more links below the visible ones.
The standard output of awk pipes into YAD, but you can’t readily apply formatting or hyperlinks. You can use formatting in regular dialog text, which will appear before the other output. That’s where the yellow “Hackaday Today!” title in the adjacent screenshot gets set. In addition, you can automatically detect URLs and make them clickable using the --show-uri option.

Here’s the relevant command:

yad --text-info \
--text "<span foreground='$TITLECOLOR'><b><big><big>Hackaday Today!</big></big></b></span>" \
--show-uri --window-icon="$0.icon.png" \
--uri-color=$LINKCOLOR --width=$WIDTH --height=$HEIGHT \
--Title "Hackaday Posts" --button="Close!gtk-ok" \
--buttons-layout=center --escape-ok 2>/dev/null

You’ll notice that the –text option does take Pango formatting and the --show-uri option makes the links clickable. By default, dialogs have an Open and Cancel button, but I forced this one to have a single close button, accept escape, and I wanted the button centered.

As you can see in the screenshot, the result isn’t bad, but it does require having the title followed by a long URL that you can click on and that’s a little ugly.

Stock Dialog

Using a standard dialog instead of text-info allows better formatting.
Since the –text option works with any dialog and handles formatting, I decided to try that. The awk code was nearly the same, except for the output formatting. In addition, the output now needs to go on the command line instead of through a pipe.

This does make the script a bit more unwieldy. The awk script sets a variable, since jamming the command into the already busy YAD command line would make the script more complicated to read and work with.

The YAD command is still simple, though:

yad \
--text="$DATA" \
--window-icon="$0.icon.png" \
--width=$WIDTH --height=$HEIGHT \
--Title "Hackaday Posts" --button="Close!gtk-ok" \
--buttons-layout=center --escape-ok

The DATA variable has the formatted output text. The result looks better, as you can see in the screenshot. In either version, if you click an underlined link, your default browser should open the relevant post.

Other Choices

If you want to install either script, you can get it from GitHub. Of course, you could do this in Python or any other conventional language. There are also programs for “minimizing” another program to the tray, like AllTray or KDocker, although some of these may only work with X11 and not Wayland.

It would have been nice to have an integrated browser, although, thanks again to FreeDesktop, it is simple enough to open a URL and launch the system’s default browser.

Prefer your Hackaday feed on the command line? Check out the comments for this post. Meanwhile, send us a tip (you know, a link to your project, not a gratuity) and maybe you’ll see your own project show up on the feed.

hackaday.com/2026/01/06/linux-…