Tachometer Uses Light, Arduinos

To measure how fast something spins, most of us will reach for a tachometer without thinking much about how it works. Tachometers are often found in cars to measure engine RPM, but handheld units can be used for measuring the speed of rotation for other things as well. While some have mechanical shafts that must make physical contact with whatever you’re trying to measure, [electronoobs] has created a contactless tachometer that uses infrared light to take RPM measurements instead.

The tool uses an infrared emitter/detector pair along with an op amp to sense revolution speed. The signal from the IR detector is passed through an op amp in order to improve the quality of the signal and then that is fed into an Arduino. The device also features an OLED screen and a fine-tuning potentiometer all within its own self-contained, 3D-printed case and is powered by a 9 V battery, and can measure up to 10,000 RPM.

The only downside to this design is that a piece of white tape needs to be applied to the subject in order to get the IR detector to work properly, but this is an acceptable tradeoff for not having to make physical contact with a high-speed rotating shaft. All of the schematics and G code are available on the project site too if you want to build your own, and if you’re curious as to what other tools Arduinos have been used in be sure to check out the Arduino-based precision jig.

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Robotic Laser Keeps Cat Entertained While You Hack

Whether it’s our own cat or a neighbor’s, many of us have experienced the friendly feline keeping us company while we work, often contributing on the keyboard, sticking its head where our hands are for a closer look, or sitting on needed parts. So how to keep the crafty kitty busy elsewhere? This roboticized laser on a pan-tilt mechanism from the [circuit.io team] should do the trick.

The laser is a 650 nm laser diode mounted on a 3D printed pan-tilt system which they found on Thingiverse and modified for attaching the diode’s housing. It’s all pretty lightweight so two 9G Micro Servos do the grunt work just fine. The brain is an Arduino UNO running an open-source VarSpeedServo library for smooth movements. Also included are an HC-05 Bluetooth receiver and an Android app for controlling the laser from your phone. Set it to Autoplay or take a break and use the buttons to direct the laser yourself. See the video below for build instructions and of course their cat, [Pepper], looking like a Flamenco dancer chasing the light.

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Stretched PC Case Turned GPU Cryptominer

We don’t do financial planning here at Hackaday, so we won’t weigh in on the viability of making money mining cryptocurrency in such a volatile market. But we will say that if you’re going to build a machine to hammer away at generating Magical Internet Monies, you might as well make it cool. Even if you don’t turn a profit, at least you’ll have something interesting to look at while you weep over your electricity bill.

Sick of seeing the desktop machine he built a decade ago gathering dust, [plaggle24w5] decided to use it as the base for a cryptocurrency mining rig. Of course, none of the original internals would do him any good, but the case itself ended up being a useful base to expand on. With the addition of some 3D printed components, he stretched out the case and installed an array of video cards.

To start with, all the original plastic was ripped off, leaving just the bare steel case. He then jammed a second power supply into the original optical drive bays to provide the extra power those thirsty GPUs would soon be sucking down. He then designed some 3D printed arms which would push out the side panel of the case far enough that he could mount the video cards vertically alongside the case. Three case fans were then added to the bottom to blow air through the cards.

While [plaggle24w5] mentions this arrangement does work with the case standing up, there’s obviously not a lot of air getting to the fans on the bottom when they’re only an inch or so off the ground. Turning the case on its side, with the motherboard parallel to the floor, allows for much better airflow and results in a measurable dip in operating temperature. Just hope you never drop anything down onto the exposed motherboard…

Mining Bitcoin on desktop computers might be a distant memory, but the latest crop of cryptocurrencies are (for now) giving new players a chance to relive those heady early days.

Tiny Quad Core Module Available Soon

We get a lot of new product announcements here at Hackaday, and we run across even more. As excited as a manufacturer might be about their latest Raspberry Pi killer or cheaper Arduino clone, we usually don’t have much to say about new products unless there is something really interesting about them. Our attention was piqued though when we saw the Neutis N5. Shipping in April, the device packs a quad-core ARM processor running at 1.3 GHz with 8 GB of flash memory and 512 MB of RAM, has an extended temperature range, WiFi (802.11N), and Bluetooth (including BLE). There’s also a crypto chip, and all this is packed into a tiny package. Really tiny. Less than 41×30 mm square and less than 4.5 mm thick. There’s a Debian-based distribution and a development board. Oh and the really interesting thing is the price, which is $49 in single quantities.

Some of the I/O ports are multiplexed, but there are plenty of options including audio, Ethernet, HDMI, USB, and more. They clearly mean for these to be put into products. The module claims UL and CE certification, each unit has a unique serial number, and there is a gang programming capability.

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3D Printing Brings a Child’s Imagination to Life

Telling somebody that you’re going to make their dreams come true is a bold, and potentially kind of creepy, claim. But it’s one of those things that isn’t supposed to be taken literally; it doesn’t mean that you’re actually going to peer into their memories, extract an idea, and then manifest it into reality. That’s just crazy talk, it’s a figure of speech.

Original sketch of the CURV II

As it turns out, there’s at least one person out there who didn’t get the memo. Remembering how his father always told him about the elaborate drawings of submarines and rockets he did as a young boy, [Ronald] decided to 3D print a model of one of them as a gift. Securing his father’s old sketchpad, he paged through until he found a particularly well-developed idea of a personal sub called the CURV II.

The final result looks so incredible that we hear rumors manly tears may have been shed at the unveiling. As a general rule you should avoid making your parents cry, but if you’re going to do it, you might as well do it in style.

Considering that his father was coming up with detailed schematics for submarines in his pre-teen days, it’s probably no surprise [Ronald] has turned out to be a rather accomplished maker himself. He took the original designs and started working on a slightly more refined version of the CURV II in SolidWorks. Not only did he create a faithful re-imagining of his father’s design, he even went as far as adding an interior as well as functional details such as the rear hatch. Continue reading “3D Printing Brings a Child’s Imagination to Life”

Arduino Watchdog Has Bite And Doesn’t Need Treats

My dog Jasper isn’t much of a watchdog: he’s too interested in sleeping and chasing my cats to keep an eye on things. Fortunately, [Vadim] has come up with a more reliable alternative with this simple Arduino watchdog. It’s designed to work with crypto coin mining rigs, but it could be easily adapted for other high-uptime uses, such as file servers or doomsday weapons.

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Rapidly Prototyping Prosthetics, Braille, and Wheelchairs

We live in an amazing time where the availability of rapid prototyping tools and expertise to use them has expanded faster than at any other time in human history. We now have an amazing ability to quickly bring together creative solutions — perfect examples of this are the designs for specialized arm prosthetics, Braille printing, and custom wheelchair builds that came together last week.

Earlier this month we published details about the S.T.E.A.M. Fabrikarium program taking place at Maker’s Asylum in Mumbai. The five-day event was designed to match up groups of makers with mentors to build assistive devices which help improve the condition of differently-abled people.

The participants were split into eight teams and they came up with some amazing results at the end of the five-day program.

Hands-On: Prosthetic Designs That Go Beyond

Three teams worked on projects based on Bionico – a myoelectric prosthesis

DIY Prosthetic Socket – a Human Machine Interface : [Mahendra Pitav aka Mahen] lost his left arm during the series of train bomb blasts in Mumbai in 2006, which killed 200 and injured over 700 commuters. He uses a prosthetic arm which is essentially a three-pronged claw that is cable activated using his other good arm. While it is useful, the limited functionality restricted him from doing many simple things. The DIY Prosthetic socket team worked with [Mahen] and [Nico Huchet] from MyHumanKit (who lost his right arm in an accident 16 years back), and fabricated a prosthetic forearm for [Mahen] with a modular, 3D printed accessory socket. Embedded within the arm is a rechargeable power source that provides 5V USB output at the socket end to power the devices that are plugged in. It also provides a second port to help recharge mobile phones. Also embedded in the arm was an IR reflective sensor that can be used to sense muscle movements and help trigger specific functions of add-on circuits, for example servos.

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