Solar Powered Lawn Mower Cuts the Grass So You Don’t Have To


It takes a lot of power and energy to keep grass levels down to an appropriate level; especially when it’s hot out. If cool glasses of lemonade aren’t around, the task at hand may not be completed any time soon causing the unkempt blades of green (or yellow) vegetation outside to continue their path of growth towards the sun.

Instead of braving the oven-like temperatures which will inevitably drench the person in sweat, this solar powered robot has been created ready to take on the job. With the heart of an Arduino, this device shaves down the grass on a regular basis, rather than only chopping down the material when it gets too long. This helps to save electricity since the mower is only dealing with young and soft plants whose heads are easily lopped off without much effort.

Internally, the robot’s circuitry interfaces with an underground wiring system that defines the cutting zones within the lawn, and proves to be a simple, accurate, and reliable approach to directing the robot where to go. If the device travels under a shaded area, a battery kicks in supplying energy to the engine. When sunlight is available, that same battery accumulates the electricity, storing it for later.

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Aerodynamics? Super Honey Badger Don’t Give a @#*^@!


[Arron Bates] is a pro R/C Pilot from Australia. He’s spent the last few years chasing the dream of a fixed wing plane which could perform unlimited spins. After some promising starts with independently controlled wing spoilers, [Arron] went all in and created The Super Honey Badger. Super Honey Badger is a giant scale R/C plane with the tail of a helicopter and a soul of pure awesome.

Starting with a standard 87″ wingspan Extra 300 designed for 3D flight, [Arron] began hacking. The entire rear fuselage was removed and replaced with carbon fiber tubes. The standard Extra 300 tail assembly fit perfectly on the tubes. Between the abbreviated fuselage and the tail, [Arron] installed a tail rotor from an 800 size helicopter. A 1.25 kW brushless motor drives the tail rotor while a high-speed servo controls the pitch.

[Arron] debuted the plane at HuckFest 2013, and pulled off some amazing aerobatics. The tail rotor made 540 stall turn an easy trick to do – even with an airplane. Flat spins were a snap to enter, even from fast forward flight! Most of [Arron’s] maneuvers defy any attempt at naming them – just watch the videos after the break.

Sadly, Super Honey Badger was destroyed in May of 2014 due to a structural failure in the carbon tubes. [Arron] walked away without injury and isn’t giving up., He’s already dropping major hints about a new plane (facebook link).

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A 3D Printed Brushless Motor

brushlessBuilding electronics with 3D printers is something we see hitting the tip line from time to time, but usually these are printed circuits, not electromechanical parts like motors, solenoids, and relays. [pitrack] thought he could do better than printing out a few blinking LED circuits and designed and built a brushless motor, the same kind you would find on electric model planes and quadcopters.

In every brushless DC motor, there are a few common parts: the rotor has a few powerful magnets embedded in it, a stators with coils of wire, and the an enclosure to keep everything together. [pitrack] printed all these parts off on his Makerbot, winding each of the three coils with about 400 turns of 26 AWG magnet wire. Also embedded in the stator are a trio of hall effect sensors to make the control via an Arduino and an L6234 motor driver easy.

For his next trick, [pitrack] is going to test the efficiency of the motor and attempt to optimize it. In the long term, it should be possible to parameterize the design of one of these printed motors, effectively allowing anyone to type in the torque and Kv rating of a desired motor, plug that into an equation, and have a motor design come out the other end.
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Droning On: The Anatomy of A Drone



These last few weeks I’ve been ordering parts for the Hackaday Testbed, a basic quadcopter to be used here at Hackaday. The top question I see when surfing multicopter forums is “What should I buy”. Which frame, motors,  props, speed controller, and batteries are best?  There aren’t easy answers to these questions with respect to larger quads (300mm or more) . There are a myriad of options, and dozens of vendors to choose from.

Advice was simple in the pre-internet days of R/C planes and helicopters: just head down to your local hobby shop, and see what lines they carry. Hook up with a local club and you’ll have some buddies to teach you to fly. This advice still holds true to a certain extent. Some hobby shops carry the DJI and Blade lines of multicopters. However, their flight control systems are closed source. If you really want to dig in and adjust parameters, you have to either buy a combo package with an open source flight control system, or buy every part separately. Unfortunately, very few local hobby shops can afford to stock individual parts at that level.

In the online world there are several “big” vendors. The classic names in the USA have always been Tower Hobbies and Horizon Hobby. Some new US-based companies are All e RC and ReadyMadeRC. Several Chinese companies, including HobbyKing and RcTimer, maintain warehouses in several parts of the world. I’m only listing a few of the big names here. If I’ve left out your favorite site, drop some info in the comments section.

The killer with many of these companies is supply. A popular component will often go out of stock with no hint as to when it will be available again. When it comes to single parts like batteries, it’s easy to just order a different size. But what about motors or speed controls? These components need to be matched on a multicopter. Changing one for a different model means changing all of them, so it pays to buy a spare or two when ordering! Click past the break for a breakdown of some multicopter parts.

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[Charles’s] Epic “Total-Recap” GoKart Post


If you’ve built an electric vehicle in the past few years, you probably owe [Charles] a couple of beers. Now you can feel more indebted to him after you read his 17,500-word, 10-part post covering everything you need to know about electric go-kart design. You’ll want to grab a sandwich to keep you company.

You probably recall the Chibikart from posts earlier this summer, which is one of an endless list of EV projects [Charles] has up his sleeve. He’s been teaching MIT students how to build EV karts for a while now, and this total-recap “2.00gokart” novel is [Charles’s] way of sharing the wealth. This is more than a simple how-to guide, though. Instead, it reads like a teacher’s edition of GoKarting 101, with a few brief and important histories, walk-throughs of how the class evolved, exhaustive links to vendors, graphs, videos, and plenty of reference and documentation.

If you have even the slightest interest in electric vehicles, do yourself a favor and give it a browse. There are a couple of videos after the break, and if you need some more motivation, check out the EV skateboard that uses a lot of the same parts.

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Fail of the Week: Flaming Brushless Motor Controller


Yep, smoke and flames are usually a sign that your electronics aren’t functioning as expected. This is actually the second failure encountered while learning about brushless motor controllers.

[Michael Kohn] purchase the motor while working on a different project and it went unused for quite some time. When he came across it again he decided he should learn the not-so-dark art of BLDC control.

The first hurdle was to figure out how to drive the three-wire motor when he had been expecting only two. The answer required him to come up with switching mechanism that allows three states for each wire: positive, negative, and not connected. His solution was to use MOSFETs. It’s a good idea, but unfortunately during the first iteration they were under-spec’d and he scared the crap out of himself when one of them blew up during testing (clip #1 below). After sourcing a more robust set of MOSFETs [Micheal] went back to testing which is when this little fire broke out. The 22 gauge wires connecting the Lithium battery to the driver just couldn’t cut it. See for yourself in the second clip.

It’s been awhile since we’ve said it: Please remember the Fail of the Week is not about ridiculing the hacker who was gracious enough to document his or her failure. It’s about learning from the mistake and discussing alternatives that can help others in the future. For instance, in this case some advice in determining MOSFET specs and wire gauge for any type of motor would be quite helpful. Have at it in the comments.

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Build a Sensorless Brushless DC Motor Controller

[Davide Gironi] shows us how to implement a sensorless brushless DC motor controller (sensorless BLDC) using an ATmega8 microcontroller. In order to control a BLDC motor you need to know its rotational sequence position and speed so you can calculate and apply the correct current phase sequence to the motor windings at just the right time.

Simply said, sensorless BLDC means you’re not using a purpose built sensor to determine the motor’s position and speed, however, you are sensing the motor’s sequence position using the back EMF signal coming from one of motor’s coils that is not currently receiving power. When this back EMF signal crosses zero voltage a microcontroller can calculate the rotational speed and when to switch to the next power sequence. This technique is not good for position control motors but is great for continuous motors like computer fans and drives were the slightly reduced wiring costs make this type of BLDC control favored.

If you want to build a BLDC controller we recommend starting with [Davide’s] last project on sensor controlled BLDC motors. You can also checkout these interactive demonstrations for more understanding on the different BLDC configurations.

Follow along after the break to watch the video demonstration of [Davide’s] sensorless BLDC controller controlling a motor from CD-ROM drive.

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