Misc Hacks

4072 Articles

DIY RC Controller Built With Old-School Parts

March 20, 2024 by 16 Comments

Once upon a time, RC transmitters were expensive units that cost hundreds of dollars even at the low end. Now, you can get them pretty cheaply, or, you can choose to build your own. [Phytion] did just that.

The design isn’t based around a modern microcontroller, nor does it rely on WiFi or Bluetooth connections. Instead, it’s a little more old school. It’s built using the HT12E parallel-to-serial encoder chip, and the HT12D decoder chip for the receiver. The controller uses a pair of HT12Es on the transmitter, and a pair of HT12Ds on the receiver. These accept inputs from a pair of analog joysticks and encode them as serial data. However, they essentially just act as digital joysticks in this design. The HT12Es feed into an STX882 module which transmits the data from the HT12Es over 433 MHz. Another STX882 module receives this signal, and passes it through HT12Ds for decoding.

At the receiving end, one joystick can turn four outputs on or off depending on whether it is pushed up, down, left or right. A channel select switch then allows it to do the same for four further outputs. The second joystick just mirrors the operation of the first. It’s just intended to make controlling something like an RC car easier by allowing one stick to be pushed forwards and backwards, and the other left and right.

You don’t see many designs like this anymore. Realistically, it’s possible to get far more functionality out of a design based on an ESP32 or similar wireless-capable chip. However, this one doesn’t require any complicated handshaking and powers up instantly, which is a nice bonus. Plus, it’s always interesting to see alternative designs tried out in the wild. Video after the break.

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Thrift Store CD Rack Turns Into Small Parts Storage Playground

March 17, 2024 by 15 Comments

What in the world could an accessory for an obsolete audio medium possibly have to do with keeping all your unruly bits and pieces in order? First of all, we’re not sure the CD is quite dead yet; we’ve got about a thousand of them packed away somewhere, and we’re pretty sure they’ll be back in style again one of these days. Until then, though, the lowly CD rack might be just what you need to get your shop under control.

As [Chris Borge] relates the story, he stumbled over this CD rack at a thrift sale and quickly realized its potential. All it took was some quick design work and a bit of 3D printing. Okay, a lot of 3D printing, including some large, flat expanses for the drawer bottoms, which can be a problem to print reliably. His solution was simple but clever: pause the print and insert a piece of stiff card stock to act as the drawer bottom before continuing to print the sides. This worked well but presented an adhesion problem later when he tried to print some drawer dividers, so those were printed as a separate job and inserted later.

Sadly, [Chris] notes that the CD format is not quite Gridfinity compatible, but that’s not a deal breaker. He also doesn’t provide any build files, but none are really necessary. Once you’ve got the basic footprint, what you do with your drawers is largely dependent on what you’ve got to store. The video below has a lot of ideas for what’s possible, but honestly, we’re looking at all those little parts assortment kits from Bojack and Hilitchi piled up in a drawer and just dreaming about the possibilities here. Add a voice-activated, LED inventory locator, and you’d really have something. Off to the thrift store!

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Creating A Numbers Station Of Your Very Own

March 17, 2024 by 13 Comments

Numbers stations are a weird phenomenon where odd voices read out long strings of numbers or random codewords to the confusion of the vast majority of the listening audience. If you’ve ever wanted to build one of your own, you could follow the example of [AudioWanderer].

NumberMumble, as it’s called, is a numbers station emulator. It doesn’t signal spy networks or reveal national secrets. Instead, it randomly plays audio samples using an Arduino, including characteristic bursts of white noise that make it sound more authentic. It relies on the Mozzi library to help with audio tasks, including generating white noise and playing back samples. It’s also kitted out with a filter knob for varying the tone. Audio output is via PWM.

If you want to confuse your neighbours with oddball audio, put this thing on a radio transmitter and get broadcasting. But don’t, because that’s illegal without the proper licenses or — you know — if you happen to be a real spy. Video after the break.

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Cheap DIY Microscope Lamp Makes Tiny Macro Shots Look Great

March 16, 2024 by 9 Comments

For optical microscopes, light is everything. If you don’t have a good amount of light passing through or bouncing off your sample, you’ve got nothing for your eyeballs or a camera to pick up. To aid in this regard, [Halogenek] whipped up a nifty microscope lamp with some LEDs.

The build uses a neat arch-shaped PCB with a hole in the middle for the microscope’s optics to pass through. Surrounding this are the LEDs, which provide a circle of light focused on the sample, akin to the ring lights so favored by today’s online influencers. The LEDs are powered via USB C, so the lamp can be run off of any garden-variety phone charger you might have lying around.

[Halogenek] reports that the lamp has proven useful for extreme macro shots of PCBs. It’s an easy build to replicate or redesign your own way if you’re doing similar work.

Microscopes are super useful, and there are all kinds of hacks you can do to make them perform better in your quest for science. Meanwhile, if you’ve been jazzing up your own lab hardware, let us know—we’d love to hear about it!

The Perils Of Return Path Gaps

March 15, 2024 by 9 Comments

The radio frequency world is full of mysteries, some of which seem to take a lifetime to master. And even then, it seems like there’s always something more to learn, and some new subtlety that can turn a good design on paper into a nightmare of unwanted interference and unexpected consequences in the real world.

As [Ken Wyatt] aptly demonstrates in the video below, where you put gaps in return paths on a PCB is one way to really screw things up. His demo system is simple: a pair of insulated wires running from the center pins on BNC jacks and running along the surface of a piece of copper-clad board to simulate a PCB trace. The end of each wire is connected to the board’s ground plane through a 50 ohm resistor, with one wire running over a narrow slot cut into the board. A harmonics-rich signal is fed into each trace while an H-field EMC probe connected to a spectrum analyzer is run along the length of the trace.

With the trace running over the solid ground plane, the harmonics are plentiful, as expected, but they fall off very quickly away from the trace. But over on the trace with the gapped return trace it’s a far different story. The harmonics are still there, but they’re about 5 dBmV higher in the vicinity of the gap. [Ken] also uses the probe to show just how far from the signal trace the return path extends to get around the gap. And even worse, the gap makes it so that harmonics are detectable on the unpowered trace. He also uses a current probe to show how common-mode current will radiate from a long conductor attached to the backplane, and that it’s about 20 dB higher with the gapped trace.

Hats off to [Ken] for this simple explanation and vivid reminder to watch return paths on clock traces and other high-frequency signals. Need an EMC probe to check your work? A bit of rigid coax and an SDR are all you need.  Continue reading “The Perils Of Return Path Gaps” →

Building A Hydraulic Loader For A Lawn Tractor

March 14, 2024 by 10 Comments

Lawn tractors are a great way to mow a large yard or small paddock. They save you the effort of pushing a mower around and they’re fun to drive, to boot. However, they can be even more fun with the addition of some extra hardware. The hydraulic loader build from [Workshop from Scratch] demonstrates exactly how.

The build is based around a John Deere LX188 lawn tractor, which runs a 17 horsepower Kawasaki engine and features a hydrostatic transmission. It’s a perfectly fine way to mow a lawn. In this case, though, it’s given new abilities with the addition of a real working loader. It’s fabricated from raw steel from the arms right down to the bucket. It’s all run from a hydraulic pump, which is mounted to the engine via an electromagnetic clutch. The clutch can be engaged when it’s desired to use the hydraulics to actuate the loader.

As you might expect, the humble lawn tractor isn’t built for this kind of work. Thus, to support the extra equipment, the mower was also given some frame reinforcements and a wider track for stability.

If you’re trying to give your neighbours mower envy, this is how you do it. Or, you could go another route entirely. Video after the break.
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A 555-Shaped Discrete Component 555

March 11, 2024 by 2 Comments

While the “should have used a 555” meme is strong around these parts, we absolutely agree with [Kelvin Brammer]’s decision to make this 555-shaped plug-in replacement for the 555 timer chip using discrete parts, rather than just a boring old chip.

As [Kelvin] relates, this project started a while back as an attempt to both learn EDA and teach students about the inner workings of the venerable timer chip. The result was a 555-equivalent circuit on a through-hole PCB, with the components nicely laid out into the IC’s functional blocks. As a bonus, the PCB was attached to an 8-pin header which could be plugged right in as a direct replacement for the chip.

Fast forward a few years, and [Kelvin] needed to learn yet another EDA package; what better way than to repeat the 555 project? It was also a good time to step into SMD design, as well as add a little zazzle. While the updated circuit isn’t as illustrative of the internal arrangement of the 555, the visual celebration of the “triple nickel” is more than worth it. And, just like the earlier version, this one has a header so you can just plug and chug — with style.

Want to know how the 555 came to be? We’ve covered that. You can also look at some basic 555 circuits to put your 555-shaped 555 to work. We’ve even seen a vacuum tube 555 if that’s more your thing.