A secret lair isn’t much fun if it’s a pain to get into, so Instructables user SPECTREcat decided to automate his hidden doors using an Arduino Uno. This drives four linear actuators via a MultiMoto shield, which both pull and turn the bookshelf in such a way that the books stay in place.

When opening, the doors first pull apart with one set of actuators, then turn with the other two to allow enough space for a person to pass through. Instead of drilling a hole through the maple plywood shelves, SPECTREcat chose to use a reed switch that’s activated on the other side by a magnet taped inside a DVD cover.

Beyond that, there’ s a PIR sensor that automatically closes the doors if motion isn’t detected for two hours. There’s also an emergency ingress/egress feature in the event of a power failure.

Looking for a hidden bookcase of your own? You can find more on the project’s electronics here, and see how the doors were constructed mechanically in this separate write-up.

We aren’t sure this technically qualifies as music synthesis, but what else do you call a computer playing music? In this case, the computer is a Teensy, and the music comes from a common classroom instrument: a plastic recorder. The mistaken “flute” label comes from the original project. The contraption uses solenoids to operate 3D printed “fingers” and an air pump — this is much easier with a recorder since (unlike a flue) it just needs reasonable air pressure to generate sound.

A Teensy 3.2 programmed using the Teensyduino IDE drives the solenoids. The board reads MIDI command sent over USB from a PC and translates them into the commands for this excellent driver board. It connects TIP31C transistors, along with flyback diodes, to the solenoids via a terminal strip.

On the PC, a program called Ableton sends the MIDI messages to the Teensy. MIDI message have three parts: one sets the message type and channel, another sets the velocity, and one sets the pitch. The code here only looks at the pitch.

This is one of those projects that would be a lot harder without a 3D printer. There are other ways to actuate the finger holes, but being able to make an exact-fitting bracket is very useful. Alas, we couldn’t find a video demo. If you know of one, please drop the link in the comments below.

We have seen bagpipe robots (in fact, we’ve seen several). We’ve also seen hammering shotguns into flutes, which is certainly more melodious than plowshares.

Desk toys are perfect for when you don’t want to work. There’s a particularly old desk toy called the Newton’s cradle. If you don’t know the name, you’d still recognize the toy. It is some ball bearings suspended in midair on strings. If you pull back, say, two balls and let them swing to impact the other balls, the same number of balls on the other side will fly out. When they return, the same number will move on the other side and this repeats until friction wears it all down.

We think [JimRD] might be carried away on procrastination. You see, he not only has a Newton’s cradle, he has automated it with an Arduino. According to [Jim], this is his third attempt at doing so. You can see the current incarnation in the video, below.

There are two servos. One pulls back the balls and releases them and the other stops the balls in anticipation of the next operation. The servo that pulls the balls back is clearly magnetic. At first, we thought it was an electromagnet and that deenergizing it released the balls. That’s not the case. Instead, the servo arm has a permanent magnet, but foam decouples it from the ball so that if the arm pulls far enough away, the ball can escape.

Because of the differences in magnets, ball bearings, and other factors, if you try to duplicate this, you’ll probably have to experiment a little with the angles and speeds in the code. The ball stop servo is probably unnecessary, as long as you don’t mind waiting for the thing to wind down on its own.

If you don’t have a cradle, you could always make one yourself. We’d probably avoid using light bulbs, though.

Who didn’t dream of a hidden door or secret passage in the house when they were kids? Some of us still do! [SPECTREcat] had already built a secret door in a fully functioning bookcase with a unique opening mechanism. The intriguing mechanism allows the doors to start by sliding slightly away form one another before hinging into the hidden space. Their operation was, however, was manual. The next step was to automate the secret door opening mechanism with electronics.

The project brain is an off-the-shelf Arduino Uno paired with a MultiMoto Arduino shield to drive 4 Progressive Automations PA-14 linear actuators. These linear actuators have 50lb force, allowing the doors to fully open or close within 10 seconds and maintain a speed that wouldn’t throw the books off the bookcases.

Not wanting to drill a hole through the bookshelf for a switch or other opening mechanisms, [SPECTREcat] added a reed switch that is activated on the other side by a DVD cover with a magnet inside. In addition to that, there is a PIR sensor on the inside room to automatically close the doors if no motion is detected for 2 hours. Dont worry, there’s also a manual switch inside just in case.

Using one of the items on the shelf to trigger the secret passage is a classic move. He could also have used a secret knock code, like the Secret Attic Library Door we covered in the past. Check out the video below to see the hinge and slide movement in action.

[Imetomi] found himself salvaging a camera from a broken drone when he decided to use it in a new project, a tracked robot with a live video feed from the mounted camera.

… I had a cheap Chinese drone that was broken, but its camera seemed to be operating and when I took apart my drone I found a small WiFi chip with a video transmitter. I (decided) that I will use this little circuit for a project and I started to buy and salvage the parts.

Being a tracked robot, it can negotiate most types of terrain and climb hills up to 40 degrees. It is powered by two 18650 lithium-ion batteries with a capacity of 2600 mAh and the remote control is based on the HC-12 serial communication module. You can control it with a joystick and watch the camera’s live-stream in a virtual reality glass. That’s pretty neat but it’s not all.

[Imetomi] also used a hacked Nacomimi Brainwave Toy to make a brain controlled version of his robot. The brainwaves are detected using sensors placed on the scalp. To actually control it the operator has to focus on the right hand to move right, focus on the left hand to move left, blink to move forward and blink again to stop. There is also an ultrasonic sensor to help navigation so the robot doesn’t bump into things. It’s not very precise but you can always build the joystick version or, even better, make a version with both controls.

We covered an Arduino brain computer interfaces way back in 2009 and the suggestion we made was a brain controlled beer bot. But this is quite cool too. You can find the build instructions here. If you build one, lets us know how the brain control works for you.

[via arduino.cc]

Coffee tables are useful for putting coffee, food, or perhaps way too much junk on, but it’s 2017—we can do better than that! Akshay Baweja certainly has at least with Dot², an interactive piece of furniture that can run animations, display lighting effects, and play old-school games.

The Arduino Mega-based table features a matrix of 296 LEDs that shine up through sections of diffused acrylic, and uses a grid of foam board strips to keep each light in a square. Dot² can be controlled either by a PC running GLEDIATOR software, or via a smartphone using a Bluetooth connection and its own custom app.

The outside doesn’t look too shabby either. With an interesting wood pattern on the side, even when off it seems like there could be something more lurking just below the table’s glass!

Want to build one of your own? Head over to this incredible project’s Instructables page to get started. And, if you’d like to know more about how it’s controlled, check out Baweja’s app here or GLEDIATOR’s site for the computer software he used.

ever wondered how strong your magnets really are?

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The post Measuring Magnet Strength with a Dual Sensor Gauss Meter appeared first on Make: DIY Projects and Ideas for Makers.

[Niklas Roy] has always wanted to try out thermal imaging and saw his opportunity when he received one of those handheld IR thermometers as a gift. But not content with just pointing it at different spots and looking at the temperatures on the LCD display, he decided to use it as the basis for a scanning, thermal imaging system that would display a heat map of a chosen location on his laptop.

He still wanted to to be able to use the IR thermometer as normal at a later date so cutting it open was not an option. Instead he firmly mounted a webcam to it pointing at the LCD display. He then wrote software on his laptop to process the resulting image and figure out what temperature was being displayed.

Once he got that working, he next put the thermometer on a platform with servos connected to an Arduino for slowly rotating it in the horizontal and vertical directions, also under control of the software on his laptop. Each time the thermometer measures the temperature of a spot, the software decodes the temperature on the LCD display and then tells the Arduino to use the servos to point the thermometer at the next spot to be measured. Each measurement takes a little time, so scanning an entire location as 70×44 spots takes around a half hour. But the end result is a heat map drawn on the laptop, done by a device that is low-tech. [Editor’s Snark: Because attaching a webcam and processing the images is “low-tech” these days.] He can overlay the heat map on a normal photo to see at a glance where the hot spots are.

The software he wrote is available on GitHub and the video below shows it in action. We’ve got to admit, it’s pretty awesome to watch. You can even see the heat map being filled in one measurement at a time.

[Niklas] is somewhat of a regular here on Hackaday and his projects span an impressive range of creative ideas. Check out his massive music construction machine, or his RC beer crate delivery robot, or his supersized DIY pinball machine. Whatever you do [Niklas], keep those creative juices flowing!

After making his first drum with a laser cutter, Ryo Kosaka redesigned it as a 3D-printed structure so more people could build it.

If you’d like to practice playing the drums, but would rather not disturb your family, roommate, neighbors, dog, etc., then an electronic version is probably a good idea. Since you’re reading our blog, making one would be even better!

Although details on how it was interfaced software-wise with the Arduino Uno aren’t included in his log, the drum itself looks quite good. It’s 3D-printed out of several individual pieces, which are glued together using thick paper to help hold everything intact. The sectioned design means that you only need a 120mm x 120mm print area to produce this 8-inch drum pad.

Kosaka also goes into how to set up the piezo sensor for drum use in his write-up, which should be quite useful for this design, or even something derived from it. You can check out the project page for more details as well as Thingiverse for the print files. Additionally, Kosaka recommends this Rockband controller to MIDI Instructable or this one featuring a homemade electronic drum kit.

We’ve all seen geodesic domes in one form or another, whether as a modern experiment, as housing from a bygone era, or perhaps as a gigantic structure in Orlando (technically a geodesic sphere). Jon Bumstead apparently wasn’t satisfied with current dome options, and instead created his own, integrating elements from programmable LED tables to make it interactive.

The resulting build is quite spectacular. Each triangular section able to be lit up with an RGB LED, and further information is output to five MIDI signals in order to produce sound. This means that up to five people can play the dome as an instrument simultaneously. If that wasn’t enough, the Arduino Uno-based dome is programmed to play a version of Simon or Pong, and can be set up to display a light show!

I constructed a geodesic dome consisting of 120 triangles with an LED and sensor at each triangle. Each LED can be addressed individually and each sensor is tuned specifically for a single triangle. The dome is programmed with an Arduino to light up and produce a MIDI signal depending on which triangle you place your hand.

Pretty cool, right? Head over to the project’s Instructables page to see more, or if you’d like information on constructing the dome itself, check out Domerama.