‘Ol Painless Paintball Mini-gun Packs a Mean Punch

Ol Painless Mini Gun

Remember Predator? Of course you do. This is [Corsae's] personal paintball gun rendition of one of the guns from it, ‘Ol Painless.

It’s a beautiful piece of work with countless man-hours going into its creation. At the core is an off-the-shelf EGO 08 paintball gun with a 20″ barrel. The barrel spacers are made out of MDF, cut by hand using a jigsaw with a barrel guide. The guide itself was made on a CNC router — too bad he couldn’t use it for everything! Each barrel is a thick-walled aluminum tube, carefully fit into the guides, and spray painted matte black for a clean finish. Sadly, they are only for aesthetics, as the paint balls shoot out through the central barrel only.

Not to worry though — while the paint balls may not come out of the barrels, the whole thing spins menacingly, which brings us to our favorite part of the project — the electronics. With help from his friend he designed a custom Arduino shield to control the motor, status LEDs and solenoid trigger. It’s fairly basic, but cool nonetheless. It features some wire connectors, diodes, an LED and the motor driver. Since the PCB fabrication cost included screen printing, he even threw on a mini-gun logo.

He’s done great job documenting the entire project in a photo gallery, with lots of notes along the way — stick around after the break to see a video of it shredding up the field.

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MIDI Melodies Make Moody Milieu

MIDI piano lights

In this beautiful, well-documented, cat-assisted hack, [capricorn1] adds visual dimension to his impressive piano skills by using his keyboard’s MIDI output to drive Edison bulbs.

He hung them from a rod of electrical conduit pipe and threaded the wires through it to a DB25 connector. The lights are controlled by an Arduino Mega plus a custom shield with an optocoupler to handle zero cross detection. He happened to already have a board with 12 SSRs on it from another project. All of the electronics are in a re-purposed switch box—the switches control four different modes: classic, velocity, scrolling, and automatic. You’ll see the scrolling mode in the video after the jump.

[capricorn1] used a small sampling of the Arduino MIDI Library, namely the note on/off functions and the control change function to handle his sustain pedal. He’s listed the full code for the project, which includes usage of the ipMIDI module for automation over WiFi.

If you don’t have a MIDI keyboard or any Edison bulbs, you could make a MIDI floor piano. You’re required to play both “Chopsticks” and “Heart and Soul” on it, though. Those are like the Hello, World for floor pianos.

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640×480 VGA On An Arduino

VGAThere are dozens, if not hundreds of examples around the Intertubes of an Arduino generating a VGA video output. The Arduino isn’t the fastest chip by far, and so far, all of these VGA generation techniques have peaked out at lower resolutions if you want to control individual pixels.[PK] has an interesting technique to generate 640×480 VGA at 60 frames per second without overclocking. It’s hacky, it’s ugly, but surprisingly, it actually works.

The VGA standard of 640×480 @ 60 fps requires pixels to be clocked out at 25.175 MHz, and the ATMega chips found in Arduinos top out at 20 MHz. [PK] wanted to generate VGA signals without overclocking, He did this by doubling the clock frequency with digital logic. The ATMega generates a clock, an inverter delays that clock so it is 90 degrees out of phase, and the two clocks are XORed, doubling clock output of the micro. It produces a very ugly square wave at 32 MHz – an error of 27% compared to the VGA spec. Somehow it still works.

With a hilariously out of spec clock, the rest of the project was pulled together from [Nick Gammon]‘s VGA library, a 16×16 font set, and a project from [lft]. Video below.

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Beating Simon


Virtually everyone has played Simon, that electronic memory game from the 70s, but who among us has actually beaten it? That was the goal of [Ben] and his 7-year-old daughter, and after a year of work, an Arduino, some servos, and a few Lego bricks, they’ve finally done it.

Instead of the large original Simon, [Ben] is using a key chain version of the game: much smaller, and much easier to build a device to sense the lights and push the buttons. The arms are made from Lego bricks, held up with rubber bands and actuated with two servos mounted on a cutting board.

To detect Simon’s lights, [Ben] connected four phototransistors to an Arduino. The Arduino records the pattern of lights on the Simon, and activates the Lego arms in response to that pattern. [Ben]‘s version of Simon has only a maximum of 32 steps in the final sequence, but that still means each game takes 528 button presses – and a lot of annoying beeps – to complete.

Videos below.

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Attiny PWM Generator and Servo Tester


Having the right tool for the job makes all the difference, especially for the types of projects we feature here at Hackaday. [Jan_Henrik's] must agree with this sentiment, one of his latest projects involves building a tool to generate a PWM signal and test servos using an Attiny25/45/85.

Tools come in all kinds of different shapes and sizes. Even if it might not be as widely used as [Jan_Henrik's] earlier work that combines an oscilloscope and signal generator, having a tool that you can rely upon to test servos and generate a PWM can be very useful. This well written Instructable provides all the details you need to build your own, including the schematic and the necessary code (available on GitHub). The final PWM generator looks great. For simple projects, sometimes a protoboard is all you need. It would be very cool to see a custom PCB made for this project in the future.

What tools have you build recently? Indeed, there is a tool for every problem. Think outside the (tool) box and let us know what you have made!

A Tweeting Litter Box


How can you not be interested in a project that uses load cells, Bluetooth, a Raspberry Pi, and Twitter. Even for those of our readers without a cat, [Scott's] tweeting litter box is worth the read.

Each aspect of this project can be re-purposed for almost any application. The inexpensive load cells, which available from eBay and other retailers, is used to sense when a cat is inside the litter box. Typically sensors like the load cell (that contain a strain gauge) this use a Wheatstone bridge, which is very important for maximizing the sensitivity of resistive sensor. The output then goes to a HX711, which is an ADC specifically built for load cells. A simple alternative would be using an instrumentation amplifier and the built-in ADC of the Arduino. Now, the magic happens. The weight reading is transmitted via an HC-06 Bluetooth module to a Raspberry Pi. Using a simple Perl script, the excreted weight, duration, and the cat’s resulting body weight is then tweeted!

Very nice work! This is a well thought out project that we could see being expanded to recognize the difference between multiple cats (or any other animal that goes inside).

Cheap-Thermocam Gets an Impressive Rehaul


[Max Ritter] is a 21 year old student of information technology at the University of Applied Science at Weingarten, Germany. Three years ago he brought us the DIY Cheap-Thermocam, a tool for thermal imaging that cost <$100. Since then he’s made a few upgrades.

The original Cheap-Thermocam made use of an Arduino, the sensor from a thermometer gun and a few XY servos. In about 2 minutes the XY servos can scan and measure 1344 points using the thermometer’s sensor, creating a heat-vision map of 42 x 32 pixels — not amazing, but it worked — and it was cheap!

The new version (V3) has its own ARM Cortex M3 processor, it measures 3072 points in 2 minutes from -70°C to 380°C with an accuracy of 0.5°C, and it exports its images at a resolution of 640 x 480 –close to commercial offerings! It’s not capable of real-time scanning, but for the majority of purposes you need one of these for — it’s really not that necessary.

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