SDR Toolkit Bends Weather Station To Hacker’s Whims

December 17, 2021 by Tom Nardi 9 Comments

We probably don’t have to tell most Hackaday readers why the current wave of low-cost software defined radios (SDRs) are such a big deal for hackers looking to explore the wide world of wireless signals. But if you do need a refresher as to what kind of SDR hardware and software should be in your bag of tricks, then this fantastically detailed account from [RK] about how he hacked his La Crosse WS-9611U-IT weather station is a perfect example.

Looking to brush up his radio hacking skills, [RK] set out to use the ADALM-PLUTO software defined radio from Analog Devices to intercept signals between the La Crosse base station and its assorted wireless sensors. He notes that a $20 USD RTL-SDR dongle could do just as well if you only wanted to receive, but since his ultimate goal was to spoof a temperature sensor and introduce spurious data into the system, he needed an SDR that had transmit capabilities.

No matter your hardware, Universal Radio Hacker (URH) is the software that’s going to be doing the heavy lifting. In his write-up, [RK] walks the reader through every step required to find, capture, and eventually decode the transmissions coming from a TX29U wireless temperature sensor. While the specifics will naturally change a bit depending on the device you’re personally looking to listen in on, the general workflow is going to be more or less the same.

In the end, [RK] is not only able to receive the data coming from the wireless sensors, but he can transmit his own spoofed data that the weather station accepts as legitimate. Getting there took some extra effort, as he had to figure out the proper CRC algorithm being used. But as luck would have it, he found a Hackaday article from a couple years back that talked about doing exactly that, which help put him on the right path. Now he can make the little animated guy on the weather station’s screen don a winter coat in the middle of July. Check out the video below for a demonstration of this particular piece of radio prestidigitation.

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The Second Worst CAD Package Ever

December 17, 2021 by Dave Rowntree 28 Comments

A while back, [Heavydeck] remembered stumbling across the worst CAD package ever, which is a schematic editor whose existence was purely intended for use to make quick circuit sketches for documentation, presentations and the like. All good. But, being based on low quality JPEG graphics, which when blown up to projector size on a big screen, they look really rough. After deciding that the original nasty, clunky interface was just nasty and clunky enough, [Heavydeck] then proceeded to reimplement the idea over the course of an afternoon, and came up with Kludge (possibly the second worst CAD package ever) making an actually useful tool even more useful.

You see, whether you make website content, YouTube tutorials, or just need to write technical reports, if you’re in the electronics business, you’re going to need to make high-quality editable schematic images at some point, and Kludge might well solve some problems for you. Kludge lets you do so many things; you can save a schematic, you can load a schematic, you can even export it to an SVG file. Actually, that’s all you can do, but it is actually just enough. Once you’ve got an image as an SVG, you can whack that into Inkscape to add some more details and you’re done. We demonstrate this with the image above, which was not annoying at all to create.

So here’s to Kludging your way around a problem, and hoping that the somewhat limited symbol library may expand a little more in the future!

Implementing A CPU Using 555 Timers And Logic Synthesis

December 17, 2021 by Dave Rowntree 26 Comments

There is many a comment on these here pages along the lines of “Why did you use a microcontroller, when you could just have easily used a 555 timer!” And, yes, we sometimes agree with the sentiment, but when a chance comment seen by Hackaday.io user [Tim Böscke] suggested turning it around and building a microcontroller out of 555 timers, the gauntlet was well and truly thrown down. Now let’s be clear, this is not the first time we’ve come across this idea, there was a breadboard 555 based build ten years ago, but this is the first time we’ve seen it done by leveraging open source synthesis targeting a PCB!

The first logic element was a simple inverter, constructed by tying the TRIGger and THReShold pins together.

LTSpice model of a NAND gate implemented with 555 and diodes

From there it was a simple matter of adding a few diode-resistor networks to the input, to effect a NAND2 gate and a NOR2 gate. Development was speeded up a bit by modeling the logic circuits in LTSpice, to find the best combination of part values. From these simple elements, all further logic functions could be implemented. Next a memory element was needed. As luck would have it, the 555 has a RS flip flop as part of its circuit, fed by dual comparator inputs. All that was needed was to bias the THRS input at Vdd/2 and then feed the data in via a pass transistor, and hey presto! a serviceable, albeit slow latch.

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3D Printing A Cyclonic Dust Separator

December 17, 2021 by Lewin Day 20 Comments

[rctestflight] recently purchased a big CNC router, and that meant it was time to arrange for some dust extraction in the workshop. Naturally, he set about building this himself!

Using a shop vac is fine at smaller scales, but they can quickly be filled up on bigger jobs. To stop it getting filled up as quickly and wasting vacuum bags, [rctestflight] wanted to build a 3D-printed cyclonic separator to catch and dump the heavier-than-air particles from the routing process into an attached bucket.

[rctestflight] trialed a variety of designs, from a quad cyclone, to a large single cyclone and even a triple-series design. A diffuser design was also built, that aims to slow the air flow to the point where particles drop out of the air stream. At the end of the day, the large mono-cyclone design proved to be the most effective at removing particles from the airstream.

Fundamentally, if you’re making lots of dust, a cyclonic separator is a great way to go about dealing with the problem. We’ve seen similar builds scaled up to deal with the needs of a whole workshop, too. Video after the break.

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Building A Custom Branding Iron With Swappable Date Blocks

December 17, 2021 by Lewin Day 6 Comments

Branding can be done on wood with just about any old bit of hot metal, but if you want to do it well, properly-crafted tooling will go a long way. [Wesley Treat] has built just that with this modular branding iron design.

The branding tooling itself is machined out of brass on an X-Carve CNC router, using [Wesley]’s own logo. The part is sanded after machining to remove tooling marks. A smaller brass slug is then machined with the numerals for various years with which [Wesley] may wish to stamp his projects.

Rather than hacking something sloppy together, the iron itself is assembled with a beautifully wood-turned handle of his own creation and a steel backing plate to hold the tooling. The date is separately removable from the main logo itself for easy changes in future. Naturally, the tool graphics are done in reverse so as to register the right way around when burned onto wood.

The tool is used with a torch to heat the brass up such that it can leave its impression on wooden surfaces. The final results are solid, if not quite perfect; getting the temperature across the tool perfectly matched would be key to getting the cleanest results. An electric heating element running in closed loop could be a way to achieve this.

Fundamentally, it’s a tidy way to mark your wooden projects in a hurry. We’ve seen wood burning reach even greater heights, too, such as with this CNC pyrography machine. Video after the break.

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Error Codes And The Law Of Least Astonishment

December 17, 2021 by Al Williams 73 Comments

Do you know the law of least astonishment? I am not sure of its origin, but I first learned it from the excellent “Tao of Programming.” Simply put, it is the principle that software should always respond to the users in a way that least astonishes them. In other words, printing a document shouldn’t erase it from your file system.

Following the law of least astonishment, what should a program do when it hits a hard error? You might say that it should let the user know. Unfortunately, many systems just brush it under the rug these days.

I think it started with Windows. Or maybe the Mac. The thinking goes that end users are too stupid or too afraid of error codes or detailed messages so we are just leaving them out. Case in point: My wife’s iPhone wouldn’t upload pictures. I’m no expert since I carry an Android device, but I agreed to look at it. No matter what I tried, I got the same useless message: “Can’t upload photos right now. Please try again later.” Not only is this not very informative, but it also implies the problem is in something that might fix itself later like the network.

The real culprit? The iCloud terms of service had changed and she had not accepted the new contract. I have a feeling it might have popped up asking her to do that at some point, but for whatever reason she missed it. Until you dug into the settings and checked the box to agree to those terms, “later” was never going to happen.

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Hackaday Podcast 149: Ballerina Bot Balances, Flexures Track Cat Food, PCB Goes Under The Knife, And An ATtiny Does The 555

December 17, 2021 by Dan Maloney 2 Comments

Newly ordained Hackaday editor-in-chief Elliot Williams and staff writer Dan Maloney jump behind the podcast mic to catch you up on all this week’s essential hacks. We’ll have a Bob Ross moment with an iPad, go to ridiculous lengths to avoid ordering a 555, and cook up a Wii in toaster. Need to make a VGA adapter from logic chips? Or perhaps you want to quantify the inner depths of human consciousness? Either way, we’ve got you covered.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (55 MB)