Game On With These Open Source Arduino Buzzers

Planning a game of Hacker Jeopardy at your next meetup? You’re going to want some proper buzzers to complete the experience, but why buy when you can build? [Flute Systems] has released an open source DIY game buzzer system based on the Arduino that will help instantly elevate your game. Certainly beats just yelling across the room.

The design has been made to be as easily replicable as possible: as long as you’ve got access to a 3D printer to run off the enclosures for the buzzers and base station, you’ll be able to follow along no problem. The rest of the project consists of modular components put together with jumper wires and scraps of perfboard. Granted it might not be the most elegant solution, but there’s something to be said for projects that beginners and old salts alike can complete.

Each buzzer consists of an Arduino Pro Mini 3.3 V, a nRF24L01, and of course a big pushbutton on the top. Each one is powered by a 110 mAh 3.7 V LiPo battery, though [Flute Systems] notes that the current version of the buzzer can’t actually recharge it. You’ll need to pull the pack out and charge it manually once and awhile. Thankfully, the printed enclosure features a very clever twist-lock mechanism which makes it easy to open anytime you need to poke at the internals.

The base station uses the 5 V version of the Pro Mini, with a Adafruit PowerBoost 1000C to step up the voltage from its 2,000 mAh battery. Of course it also has a nRF24L01, and also adds a buzzer and twin four digit seven-segment LED displays. [Flute Systems] says you can expect about five hours of runtime for the base station.

An especially nice feature of this setup is that the eight digit display allows the base station to show the number of each button in the order it was received. So rather than just getting a display of who buzzed in first, you can see the chronological order in which all eight buttons were pressed. Coming up with clever applications for this capability is left as an exercise for the reader.

Of course, there’s more than one way to build a buzzer. If you don’t like the way [Flute Systems] did it, then check out this version that uses 900 MHz radios and an OLED to show the results.

Sensor Lets Gestures And An Arduino Control The Tunes

Every time we watch Minority Report we want to make wild hand gestures at our computer — most of them polite. [Rootsaid] wanted to do the same and discovered that the PAJ7620 is an easy way to read hand gestures. The little sensor has a serial interface and can recognize quite a bit of hand waving. To be precise, the device can read nine different motions: up, down, left, right, forward, backward, clockwise, anticlockwise, and wave.

There are plenty of libraries to read it for common platforms. If you have an Arduino that can act as a keyboard for a PC, the code almost writes itself. [Rootsaid] uses a specific library for the PAJ7620 and another — Nicohood — for sending media keys.

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Arduino Traffic Light Sings The Song Of Its People

Getting an old traffic light and wiring it up to do its thing inside your house isn’t exactly a new trick; it’s so common that it wouldn’t normally pass muster for these hallowed pages. Even using one up to show the real-time status of your build or system resource utilization would be pushing it at this point. To get our attention, your traffic light is going to need to have a unique hook.

So how did [Ronald Diaz] manage to get his project to stand out from the rest? Interestingly enough, it’s nothing you can see. His traffic light doesn’t just look the part, it also sounds like the real thing. With far more effort and attention to detail than you’d probably expect, he’s made it so his Australian pedestrian traffic light correctly mimics the complex chirping of the original.

Working from a video of the traffic light on YouTube, [Ronald] was able to extract and isolate the tones he was after. Performing spectral analysis on the audio sample, he was able to figure out the frequency and durations of the eleven individual tones which make up the complete pattern. From the 973 Hz tone that only lasts 25 ms to the continuous 500 Hz “woodpecker”, every element of the sound was meticulously recreated in his Arduino code.

The Arduino Pro Mini used to control the traffic light is not only responsible for playing the tones through a piezo speaker, but as you might expect, for firing off the relays which ultimately control the red and green lamps. With everything carefully orchestrated, [Ronald] can now get that authentic Australian side-of-the-road experience without having to leave the comfort of his own home.

If you’d rather your in-home traffic light be more useful than realistic, we’ve got plenty of prior art for you to check out. This traffic light that tells you how the value of Bitcoin is trending is a great example. Or maybe this one that can tell you if the Internet is down.

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CB Radio + Arduino = 6 Meter Ham Band

Somehow [hvde] wound up with a CB radio that does AM and SSB on the 11 meter band. The problem was that the radio isn’t legal where he lives. So he decided to change the radio over to work on the 6 meter band, instead.

We were a little surprised to hear this at first. Most radio circuits are tuned to pretty close tolerances and going from 27 MHz to 50 MHz seemed like quite a leap. The answer? An Arduino and a few other choice pieces of circuitry.

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Simulate Climate With An Arduino

Greenhouses create an artificial climate specifically suited to the plants you want to grow. It’s done by monitoring conditions like temperature and humidity, and making changes using things like vents, fans, irrigation, and lighting fixtures to boost temperature. But how do you know when it’s time to up the humidity, or vent some of the heat building up inside? The easy way is to use the Arduino-powered Norman climate simulator from [934Virginia] which leverages data from different locations or times of year based on NOAA weather data to mimic a particular growing environment.

Norman relies on a simple input of data about the target location, working from coordinates and specified date ranges to return minimum/maximum values for temperature and humidity weather conditions. It makes extensive use of the Dusk2Dawn library, and models other atmospheric conditions using mathematical modeling methods in order to make relatively accurate estimates of the target climate. There are some simulations on the project’s Plotly page which show what this data looks like.

This data is used by [934Virginia’s] Arduino library to compare the difference between your target climate and actual sensor readings in your greenhouse. From there you can make manual changes to the environment, or if you’re luck and already have an Arduino-based greenhouse automation system the climate adjustments can be done automatically. The project is named after Norman Borlaug, a famous soil scientist and someone worth reading about.

Editor’s Note: This article has been rewritten from the original to correct factual errors. The original article incorrectly focused on replicating a climate without the use of sensors. This project does require sensors to compare actual greenhouse conditions to historic climate conditions calculated by the library. We apologize to [934Virginia] for this and thank them for writing in to point out the errors.

Images courtesy of Wikimedia Commons.

A Look At The Basics Of Building An Arduino Watch

Miniaturization has made smart watches possible, even for the DIY maker to tinker with. For those just getting to grips with basic digital electronics, it can be daunting, however. For those just starting out, [陳亮] put together a handy guide to building the core of an Arduino-based watch.

The writeup starts at the beginning, going over the basic hardware requirements for a smart watch. This involves considering size, packaging and power draw, as well as the user interface. The build settles on an Arduino Pro Micro, as it uses the ATmega32U4 which eliminates secondary USB-to-serial chips, helping cut down on power consumption. A square IPS LCD display is used to display an analog-style watch face, and time is kept by a DS3231 real-time clock. A pair of small vibration sensors are used to wake the watch when the user moves their wrist to check the time.

While it doesn’t cover the final assembly into a watch-like form factor, it’s a handy guide on what it takes to build a working watch for those who are still getting their feet wet with hardware. Once you’ve got that down, it’s time to contemplate how you’ll build the sleek exterior. Naturally, a good maker has that covered, too.

Fail Of The Week: The Arduino Walkie That Won’t Talkie

There’s something seriously wrong with the Arduino walkie-talkie that [GreatScott!] built.

The idea is simple: build a wireless intercom so a group of motor scooter riders can talk in real-time. Yes, such products exist commercially, but that’s no fun at all. With a little ingenuity and a well-stocked parts bin, such a device should be easy to build on the cheap, right?

Apparently not. [GreatScott!] went with an Arduino-based design, partly due to familiarity with the microcontroller but also because it made the RF part of the project seemingly easier due to cheap and easily available nRF24 2.4 GHz audio streaming modules. Everything seems straightforward enough on the breadboard – an op-amp to boost the signal from the condenser mic, a somewhat low but presumably usable 16 kHz sampling rate for the ADC. The radio modules linked up, but the audio quality was heavily distorted.

[GreatScott!] assumed that the rat’s nest of jumpers on the breadboard was to blame, so he jumped right to a PCB build. It’s a logical step, but it seems like it might be where he went wrong, because the PCB version was even worse. We’d perhaps have isolated the issue with the breadboard circuit first; did the distortion come from the audio stage? Or perhaps did the digitization inject some distortion? Or could the distortion be coming from the RF stage? We’d want to answer a few questions like that before jumping to a final design.

We love that [GreatScott!] has no issue with posting his failures – we’ve covered his suboptimal CPU handwarmer, and his 3D-printed BLDC motor stator was a flop too. It’s always nice to post mortem these things to avoid a similar fate.

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