AM Ultrasonic Transmitter And Receiver

March 6, 2018 by Steven Dufresne 22 Comments

Most often ultrasonic transducers are used for distance measurements, and in the DIY world, usually as a way for robots to detect obstacles. But for a weekend project, [Vinod.S] took the ultrasonic transmitter and receiver from a distance-meter module and used amplitude modulation to send music ultrasonically from his laptop to a speaker, essentially transmitting and receiving silent, modulated sounds waves.

For the transmitter, he turned an Arduino Pro Micro into a USB sound card which he could plug into his laptop. That outputs both the audio signal and a 40 kHz carrier signal, implemented using the Arduino’s Timer1. Those go to a circuit board he designed which modulates the carrier with the audio signal using a single transistor and then sends the result out the ultrasonic transmitter.

He took care to transmit a clear signal by watching the modulated wave on an oscilloscope, looking for over-modulation and clipping while adjusting the values of resistors located between the transistor, a 5 V from the Arduino and the transmitter.

He designed the receiver side with equal care. Conceptually the circuit there is simple, consisting of the ultrasonic receiver, followed by a transistor amplifier for the modulated wave, then a diode for demodulation, another transistor amplifier, and lastly a class-D amplifier before going to a speaker.

Due to the low 40 kHz carrier frequency, the sound lacks the higher audio frequencies. But as a result of the effort he put into tuning the circuits, the sound is loud and clear. Check out the video below for an overview and to listen to the sound for yourself. Warning: Before there’s a storm of comments, yes the video’s shaky, but we think the quality of the hack more than makes up for it.

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No, Cat, This Is Not The Litter Box

March 4, 2018 by James Hobson 39 Comments

Hackaday.io user [peterquinn] has encountered a problem with his recently unruly cat peeing under the dining table. Recognizing that the household cat’s natural enemy is the spray bottle, he built an automatic cat sprayer to deter her antics.

The build is clear-cut: an Arduino Uno clone for a brain, an MG995 servo, PIR sensor, spray bottle, and assorted electronics components. [peterquinn] attached the servo to the spray bottle with a hose clamp — ensuring that the zero position is pointing at the trigger — and running a piece of cabling around the trigger that the servo will tug on. Adding a capacitor proved necessary after frying the first Uno clone, as the servo powering up would cause the Uno to reset.

The code is set up to trigger the servo — spraying the cat twice — once the PIR detects the cat for more than ten seconds. After toying with a few options, [peterquinn] is using a 9V, 2A power supply that works just fine. For now, he hopes the auto-sprayer should do the trick. If it somehow doesn’t work, [peterquinn] has mused that a drastic upgrade to the vacuum may be necessary.

Automated Syrup System Is Sweet Sweet Madness

March 3, 2018 by Tom Nardi 33 Comments

Here at Hackaday we are big fans of the TV show, “How It’s Made”. It’s not much of a stretch to assume that, as somebody who is currently reading this site, you’ve probably seen it yourself. While it’s always interesting to see the behind the scenes process to create everyday products, one of the most fascinating aspects of the show is seeing how hard it is to make things. Seriously, it’s enough to make you wonder how companies are turning a profit on some of these products when you see just how much technology and manual work is required to produce them.

That’s precisely the feeling we got when browsing through this absolutely incredible overview of how [HDC3] makes his maple syrup. If that’s not a sentence you ever thought you’d see on Hackaday, you aren’t alone. But this isn’t a rusty old pail hanging off of a tap, this is a high-tech automated system that’s capable of draining 100’s of gallons of sap from whole groves of trees. We’ll never look at a bottle of syrup in the store the same away again.

It all starts with hundreds of tiny taps that are drilled into the trees and connected to a network of flexible hoses. The plumbing arrangement is so complex that, in certain, areas high tension support wires are necessary to hold up the weight of the hoses and their sweet contents. The main hose leads to an Arduino-powered collection station which maintains a 100 kPa (29 inHg) vacuum throughout the entire system.

The sap is temporarily held in a 250 gallon container, but at this point it’s still just that: sap. It needs to be refined into something suitable for putting on your pancakes. The first step of that process utilizes a reverse osmosis filtration system to pull the water out of the sap and increase its sugar concentration. [HDC3] says the filtration system is built from eBay scores and parts from the home improvement store, and it certainly looks the part of something that would be under a kitchen sink. This system is able to increase the sugar concentration of the sap from around 2% as it comes out of the trees to 8%. But it’s still a far way off from being ready to use.

Interestingly enough, the last steps of the process are about as old-school as they come. The semi-concentrated sap is placed in a long low metal pan, and heated over a wood fire to drive off more of the water. This process continues until the sap is roughly 60% sugar, at which point it is filtered and moved into the house to finish boiling on the stove.

All told, the syrup is boiled for eight hours to bring its sugar content up to 66%. Even with the improvements [HDC3] has made to the system, he reveals that all this hard work only results in slightly more than a half-gallon of final syrup. Talk about dedication.

It probably comes as no surprise that this is the first time Hackaday has ever run a story about producing maple syrup. However we’ve seen a number of automated beer brewing systems that seem to have been tackled with similar zeal. There’s probably a conclusion to be drawn there about the average hacker’s diet, but that’s a bit outside our wheelhouse.

[via /r/DIY]

Pinging The Depths Of A Rain Barrel

March 1, 2018 by Kristina Panos 52 Comments

Rain barrels are a great way to go green, as long as your neighborhood doesn’t frown upon them. [NikonUser]’s barrel sits up high enough that he has to climb up on an old BBQ and half-dangle from the pipe to check the water level, all the while at the risk of encountering Australian spiders.

Arachnophobia, it turns out, is a great motivator. At first, [NikonUser] dreamed up a solar-powered IoT doodad that would check the level and report the result on a web page. He battled the Feature Creep and decided to build a handheld device that pings the water level with an ultrasonic sensor and displays it on a 7-segment.

Everything is contained in a water-resistant box and driven by an Arduino Pro. The box is mounted on a piece of scrap lumber that lays across the top of the barrel. This allows the HC-SR04’s eyes to peer over the edge and send pings toward the bottom. It also helps to keep the readings consistent and the electronics from taking a swim.

Operation is simple: [NikonUser] reaches up, sets the plank across the barrel, and pushes the momentary. This activates the Arduino, which prompts the HC-SR04 to take several readings. The code averages these readings, does a little math, and displays the percentage of water remaining in the barrel.

Interested in harvesting rain water, but not sure what to do with it? You can use it for laundry, pour it in the toilet tank instead of flushing, or make an automated watering system for your garden.

Definitive Dog Feeding With Arduino

February 27, 2018 by Kristina Panos 3 Comments

Some dogs have no sense of self-preservation. Given the opportunity, they will eat until they’re sick. It’s up to us humans to both feed them and remember doing it so they aren’t accidentally overfed. In a busy household with young children, the tricky part is the remembering.

[Bryan]’s family feeds their dog Chloe once a day, in the mornings. She was a rescue who spent a few years scrounging for meals on the street, so some part of her is always interested in finding food, even if she just ate. Each morning, the flurry of activity throughout the house is compounded by Chloe’s repeated requests for food, so [Bryan] got his kids involved and built a simple circuit that lets everyone know—at a glance—whether Chloe was fed.

Chloe’s kibble is kept in a touch-top wastebasket that flips open at the press of a button. [Bryan]’s dog-fed detector uses a reed switch and an Arduino clone to detect when the lid is opened. When the reed switch goes, low, the Arduino lights up an LED. The light stays on for two hours and then shuts off automatically to get ready for the next day. You don’t have to beg for a demo video, because it’s waiting for you after the break.

Since Chloe devours a bowl of food in about two minutes flat, maybe the next project for [Bryan]’s family could teach her to slow down a bit.

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Arduino BabyTV Is Big Fun At Low Resolution

February 26, 2018 by Tom Nardi 10 Comments

What kind of TV do you have? An older 720p model, or the now standard 1080p? Perhaps you’ve made the leap to the next generation, and are rocking a 4K display in the living room. All those are are fine and dandy if you just want to watch the local sportball contest, but where’s the challenge in that? With all the technology and modular components we have access to anymore, nowadays all the real hackers are making their own TVs.

Of course, when [Nikolai] built his very own LED TV, he did have to make a few concessions. For one thing, there’s no tuner on this model. Oh, and there’s the small issue of only having a 16×16 resolution. It might not be your idea of the perfect display, but it’s just perfect for his newborn son.

That’s right, [Nikolai] got his entry for the “Hacker Parent of the Year” award in early, and built an LED display for his son that he’s calling “BabyTV”.

Rather than the ~~shows~~, ~~trash~~, advertisements that they play on the kid channels, this TV only shows animated characters from retro games. We’ll concede that this project might be an elaborate Clockwork Orange style attempt at hypnotizing his son to instill an appreciation for classic gaming. But we’ll allow it.

To make his BabyTV go, [Nikolai] used a 16×16 WS2812B LED panel and an Arduino Nano. Two rotary encoders are used to allow adjusting brightness and change the character currently being shown on the screen. As a particularly clever hack, the Arduino has an IR sensor attached and is constantly watching for any signals. If an IR signal is detected, the BabyTV switches to the next image. So if Junior has a standard IR remote in his hands, any button he presses will cause the display to change to the next “channel”.

Historically speaking we haven’t seen much stuff for children here at Hackaday, but 2018 seems to be changing that. Recent projects like the incredible scratch built mini excavator and gorgeous AT-ST high chair would seem to indicate we’re currently witnessing a generation of hackers become parents. Don’t panic folks, but we might be getting old.

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Moltoduino: Arduinos All The Way Down

February 26, 2018 by Al Williams 23 Comments

It is getting difficult to find a desktop or laptop computer with only a single CPU. Even a typical ARM-based computer now probably has multiple cores. Of course, there’s nothing to stop you from using multiple microcontrollers — like the Arduino — together. To make the process neater, [Dimitris Platis] put together Moltoduino, essentially an Arduino on a shield made to plug into another Arduino. And, yes, they will stack. You can see a video about the open source boards, below.

The key is how the board brings the pins out to connections that are easy to jumper between boards. There are several obvious use cases, but one that [Dimitris] is particularly interested in is hardware-in-the-loop testing. The idea is that you can use a simulated I/O device in one computer to exchange fake data with the software under test.

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