Bike Wheel Light Flashes Just Right

When it comes to safely riding a bike around cars, the more lights, the better. Ideally, these lights would come on by themselves, so you don’t have to remember to turn them on and off every time. That’s exactly the idea behind [Jeremy Cook]’s latest build — it’s an automatic bike light that detects vibration and lights up some LEDs in response.

The build is pretty simple — a coin cell-powered ATtiny85 reads input from a spring vibration sensor and flashes the LEDs. This is meant to complement [Jeremy]’s primary bike light, which is manually operated and always on. We especially like that form follows function here — the board shape is designed to be zip-tied to the spokes so it’s as close to the action as possible. He cleverly used cardboard and a laser cutter to mock up a prototype for a board that fits between the spokes. Pretty cool for your second professionally-fabbed PCB ever, if you ask us. Ride past the break to check out the build video.

If you don’t think fireflies on your spokes are enough to keep you safe, go full rainbow party bike.

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Circuit Sculpture Vibration Sensor

Here’s your useful and beautiful circuit for the day — [New Pew]’s vibration sensor takes manual control of the flip-flop inside a 555 timer and lights an LED in response. Use it to detect those vibrations you expect, like laundry machines, or those you only suspect, like the kind that might be coming from your engine. This gadget isn’t super-precise, but it will probably get the job done.

The vibration-detecting bit is a tiny ball bearing soldered to the spring from an old pen, which is tied between the trigger and ground pins of the 555. When the chip is powered with a 9 V battery, nearby vibrations will induce wiggle in the spring, causing the ball bearing to contact the brass rod and completing the circuit. When this happens, the internal flip flop’s output goes high, which turns on the LED. Then the flip flop must be reset with a momentary button. Check out the build video after the break.

Want to pick up Earthly vibrations? You can detect earthquakes with a homemade variable capacitor, a 555, and a Raspberry Pi.

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Cornhole Boards Play Victory Songs

How do you instantly make any game better? By lighting it up and playing at night. We would normally say ‘drinking’, but we’re pretty sure that drinking is already a prerequisite for cornhole — that’s the game where you toss bean bags at holes in angled boards.

[Hardware Unknown] loves cornhole, and was gifted a set of portable, folding boards that light up around the ring for nighttime action. These turned out to be the perfect basis for reactive boards that light up and play sound whenever points are scored. Both boards have a vibration sensor to detect bags hitting the top, and an IR break-beam sensor pair across the hole. An Arduino Nano reads from the sensors and controls an amplifier and a DF Player for sound.

Players get a point and a song for landing a bag on top of the board, and three points and a different song for making it in the hole. We love the Easter egg — anyone who manages to trip both the vibration sensor and the break-beam detector at the same time will be treated to the sound of a flock of honking geese. Check out the build journey after the break.

No good at cornhole? This one doesn’t let you miss.

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Celebrate Spring With A DIY Vibration Sensor

Is your heaving pile of electronic parts shrinking by the day as you finish old back-burnered projects and come up with new ones? Try an old pastime that never gets old: rolling your own sensors using household objects. [Nematic!] needs a way to sense vibration for an upcoming project. Instead of spending $1 plus shipping and waiting who knows how long for a spring vibration sensor to come in the mail, they made one in a matter of minutes.

A spring vibration sensor is a simple device that can be used as a poor man’s accelerometer, or simply to detect vibration. All you need is a length of conductive wire, a 10 kΩ resistor, and a way to pick up those good vibrations. For the purposes of demonstration, [Nematic!] is using an Arduino Nano in the short build video after the break.

The wire is wound around the threads of a bolt to form a coil that’s just large enough for a resistor to fit inside. One end of the coil is connected to 5 V, and one leg of the resistor connects to an input pin. Together, they form a normally-open switch. When vibrations force the free ends of both to touch, the circuit is complete and the pin is pulled high.

If you make one of these and find the sensitivity is off, just twist up a new coil with stiffer or softer wire depending on the problem. Iterating doesn’t get much cheaper than wrapping wire around a bolt. We can’t wait to see how [Nematic!] will use this sensor. In the meantime, we’re planning to use one to detect when the dryer stops running and send a text.

Speaking of bargain basement sensors, did you know you can detect water leaks with two pennies, an aspirin, and a clothespin? These projects demonstrate the kind of ingenuity that can win you a pile of toys in our new Making Tech At Home contest, running now through July 28th, 2020.

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Beat This Mario Block Like It Owes You Money

People trying to replicate their favorite items and gadgets from video games is nothing new, and with desktop 3D printing now at affordable prices, we’re seeing more of these types of projects than ever. At the risk of painting with too broad a stroke, most of these projects seem to revolve around weaponry; be it a mystic sword or a cobbled together plasma rifle, it seems most gamers want to hold the same piece of gear in the physical world that they do in the digital one.

But [Jonathan Whalen] walks a different path. When provided with the power to manifest physical objects, he decided to recreate the iconic “Question Block” from the Mario franchise. But not content to just have a big yellow cube sitting idly on his desk, he decided to make it functional. While you probably shouldn’t smash your head into the thing, if you give it a good knock it will launch gold coins into the air. Unfortunately you have to provide the gold coins yourself, at least until we get that whole alchemy thing figured out.

Printing the block itself is straightforward enough. It’s simply a 145 mm yellow cube, with indents on the side to accept the question mark printed in white and glued in. A neat enough piece of decoration perhaps, but not exactly a hack.

The real magic is on the inside. An Arduino Nano and a vibration sensor are used to detect when things start to get rough, which then sets the stepper motor into motion. Through an ingenious printed rack and pinion arrangement, a rubber band is pulled back and then released. When loaded with $1 US gold coins, all you need to do is jostle the cube around to cause a coin to shoot out of the top.

If this project has got you interested in the world of 3D printed props from the world of entertainment, don’t worry, we’ve got you covered.

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Appliance Monitor Is Kinda Shaky

Lots of people set out to build appliance monitors, whether it be for the fridge, the garage door, or the washing machine. Often, it’s nicer not to cut into an appliance to make direct electrical connections, especially when mains power or water is involved. But how else can we know what the appliance is doing?

[Drew Dormann] wanted to smarten up his old washing machine, so designed a system that uses a vibration sensor to monitor appliances. It’s a simple build, pairing the 801s vibration sensor with a Raspberry Pi Zero. Naturally, adapter boards are readily available to make hooking things up easy. Then it’s just a matter of tying it all together with a simple Python script which sends notifications using Twitter & PushBullet.

It’s important to note that this approach isn’t just limited to washing machines – there’s a whole laundry list of home appliances that vibrate enough to be monitored in this way! It’s likely you could even spy on a communal microwave in this way, though you might struggle with WiFi dropouts due to interference. Build it and let us know.

[Drew]’s build is a great example of what you can put together in a few hours with parts off the shelf. For those that consider the Pi Zero overkill for this application, consider this vibration-based laundry monitor based on the ESP8266. Think you can do better? Show us what you’ve got on Hackaday.io!

Hackaday Prize Entry: Open Source FFT Spectrum Analyzer

Every machine has its own way of communicating with its operator. Some send status emails, some illuminate, but most of them vibrate and make noise. If it hums happily, that’s usually a good sign, but if it complains loudly, maintenance is overdue. [Ariel Quezada] wants to make sense of machine vibrations and draw conclusions about their overall mechanical condition from them. With his project, a 3-axis Open Source FFT Spectrum Analyzer he is not only entering the Hackaday Prize 2016 but also the highly contested field of acoustic defect recognition.

open_fft_machineFor the hardware side of the spectrum analyzer, [Ariel] equipped an Arduino Nano with an ADXL335 accelerometer, which is able to pick up vibrations within a frequency range of 0 to 1600 Hz on the X and Y axis. A film container, equipped with a strong magnet for easy installation, serves as an enclosure for the sensor. The firmware [Ariel] wrote is an efficient piece of code that samples the analog signals from the accelerometer in a free running loop at about 5000 Hz. It streams the digitized waveforms to a host computer over the serial port, where they are captured and stored by a Python script for further processing.

From there, another Python script filters the captured waveform, applies a window function, calculates the Fourier transform and plots the spectrum into a graph. With the analyzer up and running, [Ariel] went on testing the device on a large bearing of an arbitrary rotating machine he had access to. A series of tests that involved adding eccentric weights to the rotating shaft shows that the analyzer already makes it possible to discriminate between different grades of imbalance.

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