Create a Buzz with the Mini Electric Ukulele

Everyone’s heard of the “World’s Smallest Violin,” but we think it’s time for something more upbeat. [Simone Giertz] of Punch Through Design has created a mini electric ukulele using a LightBlue Bean. The Bean is an Arduino-compatible microcontroller that you can wirelessly program using Bluetooth low energy (BLE).

The ukulele’s frame is made of laser-cut plywood.  Four 1M ohm resistors are soldered to individual wire strings. A different set of wire strings in the ukulele’s neck are connected to the same ground as the Bean. In order to play this tiny instrument, a finger must be kept on the “ground” strings while the other “tone” strings are touched by a different finger. [Simone] uses Arduino’s Capacitive Sensing Library to determine which string is being touched and what the tone will be (indicated in Hz). A piezo buzzer provides the sound. There is no need to fret when the battery is depleted from using this at an all-night luau: the frame can be unscrewed with easy access to the battery. [Simone] has uploaded the Bean’s code to GitHub.

There’s no shame going solo, but we’d enjoy a show of dueling mini-ukuleles. A duet with the 3D-printed ukulele is always a possibility. Or, play this little guy while running up and down some piano stairs while the kettle fife blows off some steam.  It’ll be a musical way to brighten anyone’s day. Check out the video of the mini ukelele after the break. You can also see more of [Simone’s] work at her website.

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Scare off Squirrels and Tweet about It with the Jack-O’-Lantern Warning System

[Stephpalm] had carved a pumpkin for the first time in two decades. Unfortunately, the neighborhood squirrels were all too pleased with her work and devoured it. Her original goal for the jack-o’-lantern was to have its lights controlled over the internet. These hungry critters inspired another project instead – The Jack-’o’-Lantern Squirrel Early Warning System. There have been hacks that have dealt with pesky squirrels before, such as a trap and an automatic water turret, but they didn’t have the ability to post to social media like this system does.

The system consists of a Spark Core, a passive infrared (PIR) sensor, and a piezo buzzer. When the motion sensor is triggered the buzzer sounds, scaring away any peckish creatures lurking nearby. [Stephpalm] used an NPN transistor and 1k-Ohm resistor to provide enough current to drive the buzzer. All of these components were connected using jumper wires and a breadboard that sits on top of the pumpkin. As a nod to her original idea, [stephpalm] then created “Pumpkin Watch Code” and loaded it into the Core. It posts preset messages to a Twitter account every 45 minutes of inactivity or whenever a pesky squirrel is detected. The messages can be personalized for anyone who wants to make one of these themselves.

We wonder if it would be better to place the breadboard inside the jack-o’-lantern and carve out a couple of holes on top for the PIR sensor’s wires to come out of. That would offer some protection from the elements and prevent it from getting knocked over. We think this project could be adapted for many other uses. After the break, see a video of the system in action!

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Buzzed Buzzer gives you a Breathalyzer test while ringing in the new year

alcohol-sensing-party-buzzer

We’re not sure if there’s enough time to get a parts order delivered, but no geeky New Year’s party will be complete without a party buzzer that doubles as a Breathalyzer. The Buzzed Buzzer hides all of the necessary bits inside of a paper and plastic party favor. We guess it only buzzes if you’re over the limit? Actually that’s not the case at all. The accuracy of the sensor used in the project really just measures the presence of alcohol and can’t quantify BAC.

A Teensy 2.0 microcontroller board drives the project. Powered by a Lithium cell, it monitors an MQ-3 Alcohol gas sensor and drives a buzzer. The components are just small enough to be hidden by the cone of the party buzzer. You can see a demonstration of this in the short clip after the jump.

This is a fun project, but we’re still big fans of getting the crowd involved with this large LED meter which is hooked up to the same style of alcohol sensor.

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Cat trainer will keep them off the counters

Our cats are not allowed on the kitchen counters, and [Iron Jungle] has the same rule. But he spotted some foot prints on the hood above his range and the addition of a security camera caught this picture of [Kelso] breaking the rules. Since he’s not always around to make the fur-ball behave he built an electronic cat trainer to do it for him.

The functionality needed isn’t very intricate. You need to monitor when the cat is where it shouldn’t be and then chase it away. For the latter he grabbed an infrared range finder. When the cat passes in front of the sensor it will trigger the second part of the system: a high-pitched buzzer that’s extremely loud. Any microcontroller will have no trouble driving the system. In this case it’s a PICAXE 28X1.

You can see the trainer in action after the break. It definitely works, because just playing the video chased our own sleeping kitty out of the room.

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Simple tweak alerts you when you’ve left your headlights on

landrover-headlight-buzzer

[Paul McGuinness] owns a Series III Land Rover, and as the vehicle as formerly used by the British military, it’s lacking some of the modern amenities he was accustomed to. Overlooking the lack of power steering and all-around drum brakes, the one item that [Paul] really missed was a buzzer that let him know when he left the lights running.

On more than one occasion, he’s had to have “The Sarge” jump started after leaving the lights running all day. Explaining the humiliation involved with jump-starting a Land Rover with a Nissan Micra (an unfortunate excuse for a vehicle, known here in the states as the Nissan Versa) in his blog, [Paul] decided that he’d had enough – it was time to build a headlight warning buzzer.

The circuit itself is straightforward, consisting of a normally closed relay connected to his headlights and ignition, along with a buzzer. When the key is in the ignition and the lights are on, the relay is open and the buzzer is silent. However, if the lights are on and the relay is not supplied power from the ignition, it closes and sounds the alarm.

A simple fix for a frustrating problem – we like that.

Preheat alarm added to a basic kitchen oven

[Justin] didn’t want to keep checking if the ‘oven heating’ indicator light had gone off before popping his unbaked edibles into the oven. Many models offer a buzzer to let you know when the chosen temp is reached, but for folks who own a basic oven model there’s just a light that tells when the heating element is getting juice. Not to worry, he plied his circuit design skills and built a buzzer to alert him when the oven’s ready.

It only took a few components to accomplish the task. [Justin] uses a pair of NPN transistors triggered by a photoresistor. One transistor is responsible for switching on the buzzer, the other transistor is driven by the photoresistor and controls the base of its companion transistor (see the schematic for a better understanding).

He designed and etched a small PCB to host all the parts. As you can see above, it mounts over the indicator light and is powered by a 9V battery. There’s an on/off switch to the right so the buzzer doesn’t keep triggering while cooking, and a potentiometer allows him to fine-tune the photoresistor sensitivity.

Office game show buzzer keeps things fair and square

office-game-show-buzzer

The sales team in [Chuck’s] office is a pretty competitive bunch as you might expect, and they decided that they wanted a system which would allow them to challenge one another during their weekly meetings. The competition involves answering questions posed by their manager, but hand raising only works for so long – they needed a definitive way to tell who “buzzed in” to answer a question first.

Since [Chuck] only had a short bit of time and a tiny budget to work on, he opted to find the easiest solution to the problem, which was an Arduino-based game show buzzer system. The game display is built from an Arduino, some LEDs and an Altoids tin, while the buzzer pushbuttons were salvaged from an old radio broadcast console.

Now, when a question is posed, the salesman can buzz in to answer, knowing that only the quickest person’s button click will be registered. When it’s time for another question, the host simply clicks his buzzer to reset the console.

While it’s not quite as fancy as this game buzzer system we featured a while back, [Chuck] says it does the job perfectly and was cheap to boot.

Continue reading to see a short video of the office game buzzer system in action.

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