Hackaday Prize Entry: A Braille Keypad For SmartPhone

June 29, 2017 by Steven Dufresne 9 Comments

A few things stand out about [Vijay]’s braille keypad for smartphones. One is how ergonomic the plans for the final result are, sitting on the back of the smartphone such that you hold the phone much as you often normally would. Another is that it plugs in just like any other USB keyboard. And the last should make any vi user smile — you don’t have to move your fingers to type. You just press combinations of buttons already under your fingers.

It consists of a custom circuit board with an AtMega32U4, a 16 MHz oscillator, a Micro-USB connector and eight pushbutton switches. The AtMega32U4 allows him to use the Arduino HID library. After mapping the braille button combinations to keys, the HID library sends the key values over a USB-OTG cable to the smartphone to be accepted as if they were coming from a normal plug and play keyboard.

We have to give kudos to [Vishay] for testing with blind people experienced with braille. For example, he’s learned that if the user presses [Dots 1 2] for ‘b’ followed by [Dots 1 4] for ‘c’, they prefer to not have to remove their finger from the 1 in between the two characters, for more rapid typing. He also learned that battery management is problematic and that may be why he’s since abandoned the option of communicating over Bluetooth, leaving just USB, and thereby eliminating the need for a battery.

[Vijay]’s project is a finalist for the Internet of Useful Things Hackaday Prize and we’re eager to see what the final result will look like. But in the meantime, check out his hackaday.io and GitHub pages, and see the video below of one iteration of his keypad in use.

Continue reading “Hackaday Prize Entry: A Braille Keypad For SmartPhone” →

Making Spirographs With LEGO And Math

June 29, 2017 by John Baichtal 11 Comments

Master LEGO builder [Yoshihito Isogawa] has been on a roll lately, cranking out a number of robots that make drawings reminiscent of the classic Spirograph toy. For instance, he built an elegant drawbot out of LEGO elements, seen above. At first glance the monicker “spirograph” seems wrong, because where are the gears? However, [Yoshihito] has them stashed underneath the sheet of paper, with magnets controlling the pens.

His drawbot consists of a platform (cleverly, an inverted LEGO plate) upon which a sheet of paper is laid. One or two pen holders, each with a pair of magnets underneath, rest on the sheet of paper. Beneath the plate, two pairs of spinning magnets rotate around a double layer of 11×11 curved racks, which then play the role of the classic spirograph rings. An EV3-controlled motor powers the whole thing.

He also makes use of an obscure part–the 14-tooth bevel gear, last manufactured by LEGO in 2002 and even then it was mostly sold in part assortments intended for the education market. It’s so obscure LEGO doesn’t even provide the gear in their online building program LEGO Digital Designer, though (of course) the LDraw folks re-created it — it’s brick 4143 in the library, seen below.

Spirograph Gear Math

This gear becomes important in spirograph-style projects because tooth count is everything. There really aren’t that many spirograph designs that can be made with LEGO, because there are a limited number of gears and they mostly have the same tooth counts–the smaller ones sport 8, 12, or 16 teeth, medium-sized ones 20 or 24 teeth, and larger ones 36 or 40 — see a pattern? Such predictability may be great for a building set, but it doesn’t engender a lot of spirograph diversity.

When you compute the number of vertices in a spirograph shape, you take the least common multiple of the two gears (or sets of gears) and divide by the small gear. So a 60-tooth turntable turning a pair of 14-tooth gears has an LCM of 420, and you divide by 28 to get the number of vertices: 15. Remove one of those smaller gears and the vertices increase to 30. The challenge in creating new shapes with a LEGO spirograph lays in swapping in new gears, just like the original toy, and having more ways to come up with unusual gear ratios makes for more interesting drawings.

Another that makes the 14-tooth gear so alluring to [Yoshihito] is that it’s one of the few LEGO gears with a number of teeth not divisible by 4. Among other things this means the gear meshes with an identical gear at 90 degrees. Usually the gears have the same number for each quarter of the circumference and meshing becomes a matter of jogging one gear a scosh. This can be a problem because LEGO axles have a “plus” shaped profile, and you may not want everything on that axle tilted as well — having a 90-degree solution makes a lot of sense.

[Yoshihito] designs LEGO robots out of Isogawa Studio and has written several books on advanced LEGO techniques, published by No Starch. He specializes in small and elegant mechanisms — finding the perfect set of elements that work together effortlessly. You can see an example in the gear assembly to the right — a pair of the aforementioned 14-tooth bevel gears, turned into a normal gear with the help of that golden spacer, none other than a One Ring from LEGO’s Lord of the Rings product line. You can find videos of his projects on YouTube.

[Yoshihito] has released a number of variants of the spirographing drawbot. What’s next? Maybe a harmonograph?

Continue reading “Making Spirographs With LEGO And Math” →

An ExoArm For The Elderly

June 29, 2017 by James Hobson 10 Comments

Prosthetic and assistive technologies have come have come a long way in recent years. When there are not only major medical research organizations, but individuals getting on board designing tools to improve the lives of others? That’s something special. Enter a homebrew essay into this field: ExoArm.

Attached to the body via what was available — in this case, the support harness for a gas-powered weed-eater — which distributes the load across the upper body and an Arduino for a brain, ExoArm designer [Kristjan Berce] has since faced roadblocks with muscle sensors meant to enable more instinctive control. So — for now — functionality is limited to a simple up and down motion controlled by two switches. It is worth noting that the down switch is currently mounted in such a way that when the user moves their arm down, the ExoArm follows suit, so there is some natural feel to using the arm in its present iteration.

Continue reading “An ExoArm For The Elderly” →

Something To Think About While You’re Mowing The Lawn

June 29, 2017 by Jenny List 90 Comments

Well here we are, we’ve reached that time of year again at which our yearly ritual of resuscitating small internal combustion engines from their winter-induced morbidity is well under way. It’s lawn mowing season again, and a lot of us are spending our Saturday afternoons going up and down our little patches of grass courtesy of messers Briggs and Stratton. Where this is being written, the trusty Honda mower’s deck has unexpectedly failed, so an agricultural field topper is performing stand-in duty for a while, and leaving us with more of the rough shag pile of a steeplechaser’s course than the smooth velvet of a cricket ground. Tea on the lawn will be a mite springier this year.

When you think about it, there’s something ever so slightly odd about going to such effort over a patch of grass. Why do we do it? Because we like it? Because everyone else has one? Or simply because it’s less effort to fill the space with grass than it is to put something else there? It’s as if our little pockets of grassland have become one of those facets of our consumer culture that we never really think about, we just do. Continue reading “Something To Think About While You’re Mowing The Lawn” →

Retro-Styled Raspberry Pi Radio

June 29, 2017 by James Hobson 5 Comments

Ok, so you want a radio — but not just any radio. It has to be wireless, access a variety of music services, and must have a vintage aesthetic that belies its modern innards. Oh, and a tiny screen that displays album art, because that’s always awesome. This 1938 Emerson AX212-inspired radio delivers.

Building on the backbone of a Raspberry Pi Zero W and an Adafruit MAX 98357 mono amp chip, the crux of this single-speaker radio is the program Mopidy. Mopidy is a music player that enables streaming from multiple services, with the stipulation that you have a premium Spotify account. Once signed up, [Tinkernut] helpfully outlines how to set up Mopidy to run automatically once the Pi boots up. The addition of a screen to display album art adds flair to the design, and Adafruit’s 1.8″ TFT LCD screen is small enough to fit the bill.

But wait — there’s more!

Continue reading “Retro-Styled Raspberry Pi Radio” →

Will It Sell?

June 29, 2017 by Bob Baddeley 86 Comments

Many of us develop things for one of two purposes: to hack something cool, or to sell something cool. When hacking something cool, your target market is yourself, and you already know you’ve made the sale. If your goal is to sell the thing you are making, then a lot more thought and effort is required. You could develop the coolest product in the world, but if your target market is too small, your price is too high, your lead time is too long, or any of a dozen other factors is not quite right, you’ll be spending a lot of time and effort on what will amount to a huge disappointment. The Hackaday Prize Best Product has many great examples which let us study some of these success factors, so let’s take a look. Continue reading “Will It Sell?” →

Arduino Does Hard Science

June 28, 2017 by Al Williams 10 Comments

We don’t know why [stoppi71] needs to do gamma spectroscopy. We only know that he has made one, including a high-voltage power supply, a photomultiplier tube, and–what else–an Arduino. You also need a scintillation crystal to convert the gamma rays to visible light for the tube to pick up.

He started out using an open source multichannel analyzer (MCA) called Theremino. This connects through a sound card and runs on a PC. However, he wanted to roll his own and did so with some simple circuitry and an Arduino.

Continue reading “Arduino Does Hard Science” →