Astronomical Clock Uses Your Spare Clock Motors

July 10, 2021 by Al Williams 1 Comment

We’ll admit we are suckers for clock projects, and the more unusual, the better. We liked the look of [Peter Balch’s] astronomical clock, especially since it was handcrafted and was a relatively simple mechanism. [Peter] admits that it looks like an astronomical clock, but it isn’t the same as a complex instrument from medieval times. Instead, it uses several standard clock motors modified.

We didn’t quite follow some of the explanations for the rotation of the different elements, but the animated GIF cleared it all up. The inner and outer discs are geared at a 6:5 ratio. It takes 2 hours for the inner disc to make one rotation, meaning that every 12 hours the two discs will be back to where they began relative to one another.

Modifying the motors is fine work, requiring a good bit of disassembly and some glue. The electronics that make it tick are quite interesting. To drive the motors, a very specific pulse train is needed, but you also want to conserve battery as much as possible. A simple oscillator with a hex inverter drew more power than desired and an Arduino, even more so. A PIC12F629, though, could sleep a lot and do the job for a very low current consumption. The final clock should run a year on two AA cells.

Up Close And Personal With Some Busted Avionics

July 10, 2021 by Tom Nardi 1 Comment

When he found this broken Narco DME 890 that was headed for the trash, [Yeo Kheng Meng] did what any self-respecting hardware hacker would do: he took it back to his workbench so he could crack it open. After all, it’s not often you get to look at a piece of tech built to the exacting standards required by even outdated avionics.

DME stands for “Distance Measuring Equipment”, and as you might expect from the name, it indicates how far the aircraft is from a given target. [Yeo Kheng Meng] actually goes pretty deep into the theory behind how it works in his write-up if you’re interested in the nuts and bolts of it all, but the short version is that the pilot selects the frequency of a known station on the ground, and the distance to the target is displayed on the screen.

Inside the device, [Yeo Kheng Meng] found several densely packed boards, each isolated to minimize interference. The main PCB plays host to the Mostek MK3870 microcontroller, an 8-bit chip that screams along at 4 MHz and offers a spacious 128 bytes of RAM. It doesn’t sound like much to the modern AVR wrangler, but for 1977, it was cutting edge stuff.

Digging further, [Yeo Kheng Meng] opens up the metal cans that hold the transmitter and receiver. Thanks to the excellent documentation available for the device, which contains extensive schematics and block diagrams, he was able to ascertain the function of many of the components. Even if you’re unlikely to ever go hands on with this type of technology, it’s fascinating to see the thought and attention to detail that goes into even seemingly mundane aspects of the hardware.

Hungry for more airworthy engineering? We’ve taken a close look at some hardware pulled from a civilian airliner, as well as some battle-hardened electronics that once graced the cockpit of an AH-64 Apache attack helicopter.

Teardown: Franz Crystal Metronome

June 22, 2021 by Tom Nardi 16 Comments

I wish I could tell you that there’s some complex decision tree at play when I select a piece of hardware to take apart for this series, but ultimately it boils down two just two factors: either the gadget was something I was personally interested in, or it was cheap. An ideal candidate would check both boxes, but that’s not always the case. This time around however, I can confidently say our subject doesn’t fall into either category.

Now don’t get me wrong, at first glance I found the Franz Crystal Metronome to be intriguing in its own way. With that vintage look, how could you not? But I’m about as far from a musician as one can get, so you’d hardly find a metronome on my wish list. As for the cost, a check on eBay seems to show there’s something of a following for these old school Franz models, with ones in good condition going for $50 to $80. Admittedly not breaking the bank, but still more than I’d like to pay for something that usually ends up as a pile of parts.

That being the case, why are you currently reading about it on Hackaday? Because it exploits something of a loophole in the selection process: it doesn’t work, and somebody gave it to me to try and figure out why. So without further ado let’s find out what literally makes a Franz Crystal Metronome tick, and see if we can’t get it doing so gain.

Continue reading “Teardown: Franz Crystal Metronome” →

AVR Reverse Engineering Hack Chat

April 19, 2021 by Dan Maloney 10 Comments

Join us on Wednesday, April 21 at noon Pacific for the AVR Reverse Engineering Hack Chat with Uri Shaked!

We’ve all become familiar with the Arduino ecosystem by now, to the point where it’s almost trivially easy to whip up a quick project that implements almost every aspect of its functionality strictly in code. It’s incredibly useful, but we tend to lose sight of the fact that our Arduino sketches represent a virtual world where the IDE and a vast selection of libraries abstract away a lot of the complexity of what’s going on inside the AVR microcontroller.

While it’s certainly handy to have an environment that lets you stand up a system in a matter of minutes, it’s hardly the end of the story. There’s a lot to be gained by tapping into the power of assembly programming on the AVR, and learning how to read the datasheet and really run the thing. That was the focus of Uri Shaked’s recent well-received HackadayU course on AVR internals, and it’ll form the basis of this Hack Chat. Then again, since Uri is also leading a Raspberry Pi Pico and RP2040 course on HackadayU in a couple of weeks, we may end up talking about that too. Or we may end up chatting about something else entirely! It’s really hard to where this Hack Chat will go, given Uri’s breadth of interests and expertise, but we’re pretty sure of one thing: it won’t be boring. Make sure you log in and join the chat — where it goes is largely up to you.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, April 21 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.
Continue reading “AVR Reverse Engineering Hack Chat” →

Honey, I Shrunk The Arduino Core

April 5, 2021 by Bryan Cockfield 69 Comments

High-level programming languages do a great job of making a programmer’s job easier, but these languages often leave a lot of efficiency on the table as a compromise. While a common thought is to move into a lower-level language like assembly to improve on a program’s speed or memory use, there’s often a lot that can be done at the high level before resorting to such extremes. This, of course, is true of the Arduino platform as well, as [NerdRalph] demonstrates by shrinking the size of the Arduino core itself.

[NerdRalph] had noticed that the “blink” example program actually includes over 1 kB of extraneous code, and that more complicated programs include even more cruft. To combat this issue, he created ArduinoShrink, which seeks to make included libraries more modular and self-contained. It modifies some of the default registers and counters to use less memory and improve speed, and is also designed to improve interrupt latency as well by changing when the Arduino would otherwise disable interrupts.

While there are some limits to ArduinoShrink, such as needing to know specifics about the pins at compile time, for anyone writing programs for Arduinos that are memory-intensive or need improvements in timing, this could be a powerful new tool. If you’d prefer to go in the opposite direction to avoid ever having to learn C or assembly, though, you can always stick with running Python on your embedded devices.

Ultrasonic Sonar Detects Hidden Objects

April 2, 2021 by Bryan Cockfield 14 Comments

While early scientists and inventors famously underestimated the value of radar, through the lens of history we can see how useful it became. Even though radar uses electromagnetic waves to detect objects, the same principle has been used with other propagating waves, most often sound waves. While a well-known use of this is sonar, ultrasonic sensors can also be put to use to make a radar-like system.

This ultrasonic radar project is from [mircemk] who uses a small ultrasonic distance sensor attached to a rotating platform. A motor rotates it around a 180-degree field-of-view and an Arduino takes and records measurements during its trip. It interfaces with an application running on a computer which shows the data in real-time and maps out the location of all of the objects around the sensor. With some upgrades to the code, [mircemk] is also able to extrapolate objects hidden behind other objects as well.

While the ultrasonic sensor used in this project has a range of about a meter, there’s no reason that this principle couldn’t be used for other range-finding devices to extend its working distance. The project is similar to others we’ve seen occasionally before, but the upgrade to the software to allow it to “see” around solid objects is an equally solid upgrade.

Planetary Escape (-Room In A Box)

March 19, 2021 by Brian McEvoy 10 Comments

The trick to a fun escape room is layers. For [doktorinjh]’s Spacecase, you start with an enigmatic aluminum briefcase and a NASA drawstring backpack. A gamemaster reads the intro speech to set the mood, and you’re ready to start your escape from the planet. The first layer is the backpack with puzzles you need to solve to get into the briefcase. In there, you discover a hidden compartment and enough sci-fi references to put goofy smiles on our faces. We love to see tools reused as they are in one early puzzle, you use a UV LED to reveal a hidden message, but that light also illuminates puzzle clues later.

All the tech in Spacecase makes it a wonder of mixed media. The physical layer has laser engraved wood featuring the font from the 1975 NASA logo, buttons, knobs, LEDs, toggle switches, and a servo. Beneath the visible faceplate is an RGB sensor, audio player, speaker, and at the center is an Arduino MEGA. We’d love to get our hands on Spacecase for a game, and we’re inspired to pull out all the stops and build games with our personal touches. Maybe something with a mousetrap.

This isn’t the first escape room hardware we’ve seen and [doktorinjh] similarly made a bomb ~~diffusing~~ defusing game.

Continue reading “Planetary Escape (-Room In A Box)” →