Misc Hacks

4058 Articles

Back Up Your Data On Paper With Lots Of QR Codes

September 12, 2024 by 55 Comments

QR codes are used just about everywhere now, for checking into venues, ordering food, or just plain old advertising. But what about data storage? It’s hardly efficient, but if you want to store your files in a ridiculous paper format—there’s a way to do that, too!

QR-Backup was developed by [za3k], and is currently available as a command-line Linux tool only. It takes a file or files, and turns them into a “paper backup”—a black-and white PDF file full of QR codes that’s ready to print. That’s legitimately the whole deal—you run the code, generate the PDF, then print the file. That piece of paper is now your backup. Naturally, qr-backup works in reverse, too. You can use a scanner or webcam to recover your files from the printed page.

Currently, it achieves a storage density of 3KB/page, and [za3k] says backups of text in the single-digit megabyte range are “practical.” You can alternatively print smaller, denser codes for up to 130 KB/page.

Is it something you’ll ever likely need? No. Is it super neat and kind of funny? Yes, very much so.

We’ve seen some other neat uses for QR codes before, too—like this printer that turns digital menus into paper ones. If you’ve got your own nifty uses for these attractive squares, let us know!

Should You Run Servo Horns Or Direct Couplings In Your RC Planes?

September 7, 2024 by 22 Comments

Whenever you buy a servo, it usually comes with a little baggie full of various plastic horns. Most of us pick our favorite and use it in our projects. Some of us hack them up, glue them back together, and do all kinds of weird things with them. And others skip them entirely, going for direct drive instead. In a new video, [Dynamix Systems] explores when going direct drive is the right solution.

The video primarily concerns servos as they’re used in the context of aero modeling. In this regard, the video points out that while stock servo horns are easy to use, they can be cumbersome and clumsy. For example, you often end up with horns and control linkages protruding out into the airstream, adding drag and generally making things a bit inelegant. They can also snag on things and easily damage your servos or controls.

Using direct shaft couplers can be a much tidier solution in some respects. The servo can be coupled directly to the axis of motion, allowing it to be hidden inside a wing or tail surface. It can require a little more finesse in installation and design, but they’re much less likely to snag on things or be damaged. There’s also a drag benefit if you do it right. [Dynamix Systems] notes that you’ll want to source some shaft couplers to do this properly, which you can make yourself or buy online fairly easily.

It’s great to see how tidy direct drive really is. We’ve seen some other nifty servo tricks of late, too. Video after the break.

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Hot Water Heater Hacked To Run On Solar Juice

September 6, 2024 by 41 Comments

It’s 2024, and there’s no getting around it. Grid energy is expensive. [Darrell] realized that a lot of his money was going on water heating, and he came up with a neat solution. What if he could hack in some solar power to slash his bills at a minimum of fuss? It worked so well for him, he’s whipped up a calculator to help others do the same.

[Darrell]’s idea was simple enough. He hooked up solar panels to just the bottom heating element of his hot water heater. This cut his power bill in half. His calculator is now up at pvh20.com, and it’s designed to help you figure out if it’s feasible for you. It takes into account your location, local power prices, and the amount of sun your area tends to get on a regular basis. It also takes into account the solar panels you intend to use and your water heater to determine how many panels you’ll need for properly hot water. Key all that in, and you’re well on your way to speccing a decent solar hot water setup. From there you’ll just need to buy the right stuff and wire it all up properly.

If you live in an area where the sun shines freely and the power is more expensive than printer ink, this could be a project well worth pursuing. Cheaper hot water is a grand thing, after all. [Darrell’s] calculator is really only the first step, and it doesn’t deal with the practicalities of installation, but that’s half the fun of a good project, right? Happy hacking!

An Automatic Cat Feeder Built With A 4060 Binary Counter

September 6, 2024 by 14 Comments

We’ve seen a great many cat feeders over the years. Some rely on the Internet of Things, and some rely on fancy microcontrollers. [Larry Cook], on the other hand, built his using a simple 4060 binary counter chip.

The feeder is built out of old plywood, and the whole thing runs off an old 12-volt DC wall wart and a lead-acid battery to keep it going in a power outage. The dry cat food is stored in hopper above a drum, with the drum  rotated by a 12-volt DC gearmotor. The gearmotor is activated on a schedule—either every 4 hours, or every 5.5 hours, depending on setting. There’s then a four-digit 7-segment display for counting the total number of feedings.

The manner of operation is simple. The 4060 binary counter slowly counts up to 8,196 on a 1.11 Hz or 0.83 Hz clock, for four hour or 5.5 hour operation respectively. When it hits that threshold, it fires the gear motor. The gear motor then rotates the drum for one revolution, dumping a preset amount of food. At the end of a revolution, it triggers a hall sensor which resets the circuit.

The best thing about this design? It’s been in service for ten years. [Larry’s] original video is a big contrast to his latest one, but it shows the same feeder doing the same job, all this time.

We love a good cat feeder, and it’s great to see one built with simple old-school parts, too. Video after the break.

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Build A Super Cheap RC Trainer Plane With Foam

September 5, 2024 by 20 Comments

Once upon a time, RC planes were expensive models that took months to build and big money to equip with electronics. Since the 20th century though, powerful batteries have become cheap, as have servos and radio controllers. Combine them with a bit of old packing material and you can get a little RC trainer up and running for peanuts, as [Samm Sheperd] demonstrates.

[Samm] started referring to this as the “$5 trainer,” though he admits that it will cost more than that if you don’t have some bits and pieces laying around. He demonstrates how to cut cheap foamboard with a hot guitar string, and how to form it into a viable wing. That’s the most crucial part, with the fuselage and tail surfaces relatively simple by comparison. With that complete, it’s as simple as bolting on a motor, some servos, and control horns, and you’re up and running. You can even whip up a landing gear if you’re so inclined! Then, figure out your center of gravity, get it right, and then you’re pretty much ready to fly.

It’s a great primer on how to build a basic RC model, and if you do it right, it should have pretty forgiving handling, too. Plus, it’s so cheap that it should be easy to repair if you crash. Happy modelling! Video after the break.

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High-Speed Jelly Launcher Destroys Toast

September 5, 2024 by 10 Comments

You shouldn’t play with your food. Unless you’re designing some kind of portable cannon to fling it across the room. That’s precisely what [Backhaul Studios] did.

The first step of designing the condiment cannon was deciding what it should fire. Little low-profile tubs of jelly ended up being the ideal. They were stout enough to survive high-speed flight, while their low height was good for aerodynamics. The cannon itself is built from metal and 3D-printed parts. Multiple iterations eventually landed on a flywheel launcher design with big brushless motors and large 6-inch discs. It sounds positively awful in action and can fling jam (jelly) packets at immense speed. From there, it was simply necessary to design a magazine feed system to enable high-speed full-auto jelly delivery.

If you’ve ever hucked ketchup packets at a brick wall, you’ve understood the joy of splattering condiments everywhere. This cannon is just a way to do that faster and more hilariously. We’ve seen other fun builds along these lines before, too. Video after the break.

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Humble 555 Gets A Boost For ESR Meter

September 4, 2024 by 6 Comments

[Peter Demchenko] wanted to use a low power TS555 in an ESR meter design. The problem is, he needed to handle significant current sink requirements for cases where the capacitor under test had a low ESR. The TS555 wasn’t up to the task.

However, [Peter] made an interesting observation. the output pin of the device can sink or source current. However, the discharge pin is exactly the same output but can only sink current.

But what if you tied them together? Using some equalizing resistors, that’s exactly what he did, and this roughly doubles the rated current sink capability. According to [Peter], you do make the circuit more sensitive to power supply variations, but that could be an acceptable trade, depending on your application.

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