Nerf Gun Ammo Counter and Range Finder

The proliferation of breakout boards that the DIY electronics movement has allowed has been staggering. Buy a few different boards, wire them together to a microcontroller or credit-card computer (both on their own breakout board) and write a bit of code, and you can create some really interesting things. Take Reddit user [Lord_of_Bone]’s Nerf Gun ammo counter and range finder, for example, a great example of having a great idea and looking around for the ways to implement it.

For the range finder, [Lord_of_Bone] looked to an ultrasonic rangefinder. For the ammo counter, [Lord_of_Bone] chose a proximity sensor. To run everything, the Raspberry Pi Zero was used and the visuals were supplied by a Rainbow Hat. The range finder is self-explanatory. The proximity sensor is located at the end of the gun’s muzzle and when it detects a Nerf dart passing by it reduces the ammo count by one. Blu-tack is used to hold everything in place, but [Lord_of_Bone] plans to use Sugru when he’s past the prototype stage.

The one problem [Lord_of_Bone] has with the build is that there’s no way to tell how many Nerf bullets are in the magazine. Currently the wielder must push a button when reloading to reset the count to a preset amount. We’re sure that [Lord_of_Bone] would appreciate any suggestions the Hack-A-Day crowd could offer.

[Lord_of_Bone] gives a full bill of materials, Python code, a lot of pictures and step-by-step instructions so that you, too, can determine how far away your target is, and whether or not you have enough ammo to hit them. We have quite a few Nerf mods on the site, and [Lord_of_Bone] could take a look at this article about how to keep track of your Nerf ammo, and here’s a different method of determining if a Nerf dart has been fired (and measuring its speed.)

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Take a Spin on this Voice-Controlled 3D Scanning Rig

[Aldric Negrier] wanted to make 3D-scanning a person streamlined and simple. To that end, he created this voice-controlled 3D-scanning rig.

[Aldric] used a variety of hacking skills to make this project, and his thorough Instructable illustrates this nicely. Everything from CNC milling to Arduino programming to 3D-printing was incorporated into the making of this rig. Plywood was used to construct the base and the large toothed gear. A 12″ Lazy Susan bearing was attached to this gear to allow smooth rotation. In order to automate the rig, a 12V DC geared motor was attached to a smaller 3D-printed gear and positioned on the base. When the motor is on, the smaller gear’s teeth take the larger gear for a spin. He used a custom dual H-bridge motor driver made by a friend, which is connected to an Arduino Nano. The Nano is also connected to a Bluetooth module and an ultrasonic range finder. When an object within 1-35cm is detected on the rig for 3 seconds, the motor starts to spin, stopping when the object is no longer detected. A typical scan takes about 60 seconds.

This alone would have been a great project, but [Aldric] did not stop there. He wanted to be able to step on the rig and issue commands while being scanned. It makes sense if you want to scan yourself – get on the rig, assume the desired position, and then initiate the scan. He used the Windows speech recognition SDK to develop an application that issues commands via Bluetooth to Skanect, a 3D-scanning software. The commands are as simple as saying “Start Skanect.” You can also tell the motor to switch on or off and change its speed or direction without breaking form. [Aldric] used an Asus Xtion for a 3D-scanner, but a Kinect will also work. Afterwards, he smoothed his scans using MeshMixer, a program featured in previous hacks.

Check out the videos of the rig after the break. Voice commands are difficult to hear due to the background music in one of the videos, but if you listen carefully, you can hear them. You can also see more of [Aldric’s] projects here or on this YouTube channel.

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Brighten Your Day with Motion Controlled Cabinet Light

[Thomas Snow] found himself in a bit of a pickle. His kitchen lights didn’t adequately light his counter-tops. So instead of inventing a light bending device that could warp space-time enough to get the light where it needs to go, he decided to take the easy road and installed a motion controlled LED strip under the cabinets.

Now, these aren’t just any ‘ol motion control lights. Not only is [Thomas] able to turn the lights on and off with a wave of his hand, he can control the brightness as well. He’s doing the magic with an ultrasonic range sensor and PIR sensor. An ATTiny85 ties everything together to form the completed system.

The PIR sensor was incorporated because [Thomas] didn’t want to bug his pets with the 40kHz chirp from the ultrasonic sensor. So it only comes on when the PIR sensor sees your hand. Be sure to check out [Thomas’s] project for full source and schematics.

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Green-Sweep for Your Ultrasonic Rangefinder

Maybe you’ve never programmed an Arduino before. Or maybe you have, but nothing beyond das blinkenlights. Maybe your soldering iron sits in a corner of your garage, gazing at you reproachfully every time you walk by, like a ball begging to be thrown. Maybe you’ve made a few nifty projects, but have never interfaced them with a PC. If this describes you, then this article and project is just what you need. So grab your favorite beverage, tuck in and prepare to get motivated.

[Anuj Dutt] has not only made a really cool project, he has also done a most excellent job at documenting it. It’s an Arduino controlled “RADAR” like project that uses the familiar Parallax ultrasonic sensor. It’s mounted to a servo and feeds data to a PC where a custom VB.NET program translates the data in to a cool “green radar sweep” screen. It also pushes text to an LCD which reveals the distance from the target.

screenshot of radar program

[Anuj Dutt] hand rolled his Arduino just because, but ran into some trouble getting everything to talk to the PC. He wound up using the ultra user friendly FTDI to save the day. Be sure to check out the video below to see the project in action. [Anuj] published the code for both the Arduino and PC in the video description.

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Lamp Comes to Life with Ultrasonic Sensors

Fans of the bouncing lamp from the Pixar corporate logo will enjoy [Daniel]’s latest project. It’s a motion controlled desk lamp that uses ultrasonic sensors to control its physical position.

The core of the project is an Arduino and the three ultrasonic sensors. The sensors act as range finders, and when they are all working together under the direction of the microcontroller they can tell which direction a hand was moving when it passed by. This information is used to drive two servos, one in the base and one on the lamp’s arm.

The project requires an articulating desk lamp of some sort (others besides the specific one [Daniel] used shouldn’t be much of a problem as long as they bend in the same way). Most hackers will have the rest of the parts on hand, with the possible exception of the rangefinder. The code is up on the project site for a look-see or in case you want to build your own.

The only problem that [Daniel] had when putting this all together was that the base was a little wobbly. He was able to fix that with some thumbtacks, and we think the next step for the project should be switching the light on and off over the internet.

Axis Glove That Controls a Robot


This homemade glove and gesture controlled rover was created by [electro18]. It can send temperature, battery level, and object distance to the LCD panel on the wrist. Instead of a typical joystick, this wireless system taps into an embedded accelerometer to maneuver the robot like magic.

The main chassis platform is made of clear acrylic and has additional acrylic strips fixed to the edges for additional strength. A LM35 temperature sensor is wired to the front that monitors the environments that the rover explores. An HC-SR04 Ultrasonic Rangefinder acts as the eyes of the machine. The photodiode is covered with an adaptation of a 6mm heat shrink tube to avoid false readings. Once hooked up and turned on, the robot can be controlled with the futuristic power glove consisting of two parts. An accelerometer strap and a display strap are the biggest parts. The project shows that it is relatively easy to make a system like this. Other items like quadcopters and tiny water boats could be controlled with a similar type of setup.

A video of the axis glove maneuvering the vehicle on a slope can be seen after the break:

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