Surfsonar shows the depth of water while surfing

Surf Sensor Adds Depth To Finding The Ultimate Wave

To say that the ocean is a dynamic environment would be a gross understatement, especially when coastlines are involved. Waves crash, tides go in and out, and countless variables make even the usual conditions a guessing game. When [foobarbecue] goes surfing, he tries to take into account all of these things. The best waves at his local beach are directly over an ever-moving sand bar, and their dynamics are affected by depth, another constant variable. [foobarbecue]’s brilliant solution to understanding current conditions? Build a depth finder directly into his surf board!

At the heart of the “surfsonar” is the Ping Sonar Echosounder, a sonar transducer designed for AUV’s and ROV’s. [foobarbecue] embedded the transducer directly into the board. Data is fed to a Raspberry Pi 4b, which displays depth and confidence (a percentage of how sure it is of the measurement) on a 2.13 inch e-Paper Display Hat.

Power is provided by a PiSugar. Charging is done wirelessly, which we’d say is pretty important considering that the whole device is sealed inside a modified surfboard.

While it’s not a low budget build, and there’s yet room for improvement, early reports are positive. Once away from the breaking waves, the device confidently shows the depth. More testing will show if the surfsonar will help [foobarbecue] find that ever-moving sandbar!

Surf hacks are always welcome, we’ve featured the LED Strip Lit Surfboard as well as the Surf Window, which tells its owner if the surf is up. Be sure to let us know about any cool hacks you find when you’re out surfing the ‘net via our Tips Line!

Building A Water Rocket That Lands Via Parachute

Water rockets are plenty of fun, but they can be even more fun if you go wild with the engineering. [The Q] is one such experimenter, who built a dual-thrust water rocket that even has a parachute for landing!

The testing took place in an area strangely reminiscent of a certain operating system.

The dual-thrust concept is an interesting one, and is well explained by fellow YouTube channel [Air Command Rockets]. The basic idea is to use several chambers on the water rocket, one which provides an initial short “boost” phase of high acceleration, followed by a longer “sustain” level of acceleration from a secondary chamber.

It’s a great way to send a water rocket ever higher, but [The Q] didn’t stop there. The build was also fitted with a wind-up module from a little walking toy, colloquially referred to as a “Tomy timer” in the water rocket scene. A rubber band is wound around the timer’s output shaft, holding a door shut containing a parachute. At launch, the windup mechanism is released, and its output shaft turns, eventually releasing the parachute. The trick is setting up the timer to release the chute just after the rocket is done with its thrust phase.

It’s a neat build, and one that would serve as a great guide to those eager to start their own journey down the rabbit hole of advanced water rockets. We’ve seen similar work before, too. Video after break.

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A portrait-drawing robot on a table

Drawing Robot Creates Portraits Using Pen, Paper And Algorithms

Although the market for hand-drawn portraits largely collapsed following the invention of photography, there’s something magical about watching an artist create a lifelike image using nothing but a pencil, some paper, and their fine motor skills. Watching a machine do the same is a similarly captivating experience, though often the end result is not so great. Trying to fix this deficiency, [Joris Wegner] and [Felix Fisgus] created the Pankraz Piktograph which seems to do a pretty good job at capturing faces. They were inspired by classic picture-drawing automatons, and made a 21st-century version to be used in museums or at events like trade shows.

The operation of the Piktograph is very simple: you stand in front of the machine, look into the camera and take a selfie. If you like what you see, the robot will then begin to draw your portrait on a piece of paper. It does this using two human-like arms which are made from aluminium and driven by two stepper motors. An ordinary ballpoint pen is held in a spring-loaded carrier, which provides just enough pen-to-paper pressure to reliably draw lines without lifting off or scratching the paper. We can’t help but be impressed with the overall look of the machine: with a sleek, powder-coated aluminium case and a stainless steel stand it’s a work of art by itself.

Inside, the Piktograph is powered by a Raspberry Pi 3, which runs a rather sophisticated algorithm to generate a vector image which doesn’t take too long to draw, but still results in a recognizable image of the subject. The makers’ thesis goes into quite some detail to explain the process, which uses Canny edge detection to create an outline drawing, then fills in the empty bits to create bright and dark areas. A certain amount of noise and wigglyness is added to the lines to give it a more “handmade” feel, and the resulting drawing is divided into continuous lines for efficient drawing by the plotter.

We’ve seen several types of specialized art robots before, capable of drawing portraits with a pen, painting them, or even using an Etch-a-Sketch, but [Joris] and [Felix]’s creation seems to win on speed, workmanship, and the quality of the end result. Video embedded after the break.
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Modified Car Alternator Powers Speedy DIY E-Bike

Your garden variety automotive alternator is ripe for repurposing as is, but with a little modification, it can actually be used as a surprisingly powerful brushless motor. Looking to demonstrate the capabilities of one of these rebuilt alternators, [DIY King] bolted one to the back of a old bicycle and got some impressive, and frankly a bit terrifying, results.

We should say up front that the required modifications to the alternator are quite extensive, so before you get too excited about building your own budget e-bike, you should check out the previous guide [DIY King] put together. The short version is that you’ll need to machine a new rotor and fill it with the neodymium magnets salvaged from hoverboard motors.

A custom built alternator rotor is the key to the project.

Once you’ve got your modified alternator, the rest is relatively easy. The trickiest part of this build looks like it was cutting off the bike’s rear wheel mount and replacing it with a plate that holds the alternator and a pair of reduction gears pulled from a 125cc motorbike. Beyond that, it’s largely electronics.

Naturally, you’ll also need a pretty beefy speed controller. In this case [DIY King] is using a 200 amp water-cooled model intended for large RC boats, though interestingly enough, it doesn’t seem he’s actually running any water through the thing. He’s also put together a custom 1,500 watt-hour battery pack that lives in a MDF box mounted under the seat.

To test out his handiwork, [DIY King] took to the streets and was able to get the bike up to 70 km/h (43 MPH) before his courage ran out. He thinks the motor should be able to push it up to 85 km/h, but he says the bike started wobbling around too much for him to really open it up. In terms of range, he calculated that while cruising around at a more palatable 30 km/h (18 MPH), he should be able to get 100 kilometers (62 miles) off of a single charge.

If you like repurposed motors and suicidal bike speeds, you’ll love this build that uses a washing machine motor to push a rider to a claimed 110 km/h. If you’re not worried about speed or range, then this supercapacitor e-bike is certainly worth a look as well.

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Mastering Memory For Microcontrollers: Elecia White To Deliver Remoticon Keynote

I’m excited to share the news that Elecia White will deliver a keynote talk at the Hackaday Remoticon in just a few short weeks. Get your free ticket now!

Elecia is well-known throughout the embedded engineering world. She literally wrote the book on it — or at least a book on it, one I have had in my bedside table for reference for years: O’Reilly’s Making Embedded Systems: Design Patterns for Great Software. She hosts the weekly Embedded podcast which has published 390 episodes thus far. And of course Elecia is a principal embedded software engineer at Logical Elegance, Inc working on large autonomous off-road vehicles and deep sea science platforms.

Map of a mythical land used as a metaphor for microcontroller memory
Map metaphor used to help visualize microcontroller memory. [Source:]
For her keynote, Elecia plans to unwrap the secrets often overlooked in the memory map file generated when compiling a program for a microcontroller. Anyone who has written code for these mighty little chips has seen the .map files, but how many of us have dared to really dive in?

Elecia will use a nifty metaphor for turning the wall of text and numbers into a true map of the code. That metaphor makes the topic approachable for everyone with at least a rudimentary knowledge of how embedded systems work, and even the grizzliest veteran will walk away with tips that help when optimizing for RAM usage and/or code space, updating firmware (with or without a bootloader), and debugging difficult crash bugs.

This autumn is a busy time for Elecia. She’s been hard at work turning her book into a ten-part massive open online course (MOOC). Over the years she’s been a strong supporter of Hackaday, more than once as a judge for the Hackaday prize (here’s her tell-all following the final round judging of the 2014 Prize). She even took Hackaday on a tour of Xerox Parc.

Final Talk Announcements This Week and Next!

The Call for Proposals closed a few days ago. So far we’ve made two announcements about the accepted talks and we’ll make two more, this Thursday and next. But there’s no reason to wait. With Elecia White, Jeremy Fielding, and Keith Thorne presenting keynotes, and some superb social activities soon to be unveiled, this is an event not to be missed!

Remoticon is free to all, just head over and grab a ticket! If you want something tangible to remember the weekend by you can grab one of the $25 tickets that scores you a shirt, but either option gets you all the info you need to be at every virtual minute of the conference.

RC car without a top, showing electronics inside.

Fast Indoor Robot Watches Ceiling Lights, Instead Of The Road

[Andy]’s robot is an autonomous RC car, and he shares the localization algorithm he developed to help the car keep track of itself while it zips crazily around an indoor racetrack. Since a robot like this is perfectly capable of driving faster than it can sense, his localization method is the secret to pouring on additional speed without worrying about the car losing itself.

The regular pattern of ceiling lights makes a good foundation for the system to localize itself.

To pull this off, [Andy] uses a camera with a fisheye lens aimed up towards the ceiling, and the video is processed on a Raspberry Pi 3. His implementation is slick enough that it only takes about 1 millisecond to do a localization update, netting a precision on the order of a few centimeters. It’s sort of like a fast indoor GPS, using math to infer position based on the movement of ceiling lights.

To be useful for racing, this localization method needs to be combined with a map of the racetrack itself, which [Andy] cleverly builds by manually driving the car around the track while building the localization data. Once that is in place, the car has all it needs to autonomously zip around.

Interested in the nitty-gritty details? You’re in luck, because all of the math behind [Andy]’s algorithm is explained on the project page linked above, and the GitHub repository for [Andy]’s autonomous car has all the implementation details.

The system is location-dependent, but it works so well that [Andy] considers track localization a solved problem. Watch the system in action in the two videos embedded below.

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VCF East 2021: Novasaur TTL Computer Sets The Bar

There was certainly no shortage of unique computers on display at the 2021 Vintage Computer Festival East; that’s sort of the point. But even with the InfoAge Science and History Museum packed to the rafters with weird and wonderful computing devices stretching back to the very beginning of the digital age, Alastair Hewitt’s Novasaur was still something of an oddity.

In fact, unless you knew what it was ahead of time, you might not even recognize it as a computer. Certainly not a contemporary one, anyway. There’s nothing inside its Polycase ZN-40 enclosure that looks like a modern CPU, a bank of RAM, or a storage device. Those experienced with vintage machines would likely recognize the tight rows of Advanced Schottky TTL chips as the makings of some sort of computer that predates the 8-bit microprocessor, but its single 200 mm x 125 mm (8 in x 5 in) board seems far too small when compared to the 1970s machines that would have utilized such technology. So what is it?

Inspired by projects such as the Gigatron, Alastair describes the Novasaur as a “full-featured personal computer” built using pre-1980 components. In his design, 22 individual ICs stand in for the computer’s CPU, and another 12 are responsible for a graphics subsystem that can push text and bitmapped images out over VGA at up to 416 x 240. It has 512 K RAM,  256 K ROM, and is able to emulate the Intel 8080 fast enough to run CP/M and even play some early 80s PC games.

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