We love writing up projects that re-use lots of old parts. In fact, we save the links and use them as defense when our significant other complains about the “junk” in the basement. No, that tactic hasn’t ever worked, but we’re going to keep trying. Case in point, [Wotboa] needed a non-contact tachometer. There are plenty of commercial products which do just that. After consulting his parts bin, [wotboa] realized he had everything he needed to hack out his own. An IR break beam sensor from an old printer was a perfect fit in an aluminum tube. With the outer shell removed, the emitter and detector were mounted in the nylon shell of an old PC power supply connector, effectively turning them pair into a reflective sensor. To amplify the circuit, [wotboa] used a simple 2n2222 transistor circuit. The key is to keep the voltage seen by the sound card the range of a line level signal. This was accomplished by adding a 2.2 Megohm resistor in line with the output. [wotboa] drew his schematic in eagle, and etched his own PCB for the project. Even the tachometer’s case came from the parts bin. An old wall wart power supply gave up its shell for the cause, though [wotboa] is saving the transformer for another project.
For sensing, [wotba] used [Christian Zeitnitz’s] Soundcard Oscilloscope software. Measuring the RPM of the device under test is simply a matter of determining the frequency of the signal and multiplying by 60. A 400 Hz signal would correspond to a shaft turning at 24,000 RPM. The circuit performs well in the range of RPM [wotboa] needs, but using a sound card does have its limits. The signals on the scope look a bit distorted from the square waves one would expect. This is due to the AC coupled nature of sound cards. As the signal approaches DC, the waveform will become more distorted. One possible fix for this would be to remove the AC coupling capacitor on the sound card’s input. With the capacitor removed, an op amp buffer would be a good idea to prevent damage to the sound card.
[Saulius] couldn’t find a cost-effective wireless scale that did what he wanted, so he reverse engineered the communication protocol for an off the shelf model to get weight data himself.
[Saulius] bought a cheap Maxim 29-66SH scale that uses infra-red to communicate to a detachable digital readout. Using the USB IR toy, [Saulius] intercepted the messages that were broadcast. After a little reverse engineering and with the help of some Python scripts, he soon discovered the protocol his scale was using to encode weight messages.
Since all the communication is through IR, there is no need to do any invasion of the scale as the receiver can be placed anywhere in line of sight from the transmitter on the scale itself.
Check out the demo video for the whole thing in action. If patching into the scale isn’t hard enough, you should just build one from scratch.
Continue reading “Listening to a Smart Scale”
At the end of every semester, we get a bunch of cool and well-documented student projects from Cornell’s ECE4760 class. [Scott] and [Alex]’s infrared theremin is no exception.
The classic theremin design employs each of the player’s hands as the grounded plate of a variable capacitor in an LC circuit. For the pitch antenna, this circuit is part of the oscillator. For the volume antenna, the hand capacitor detunes another oscillator, changing the attenuation in the amplifier.
[Scott] and [Alex] put a twist on the theremin by using two IR sensors to control volume and pitch. The sensors compute the location of each hand and output a voltage inversely proportional to its distance from the hand. An ATMega1284P converts the signal to an 8-bit binary number for processing. They built four voices into it that are accessible through the push-button switch. The different voices are created with wave combinations and modulation effects. In addition to Classic Theremin, you can play in pure sine, sawtooth, and FM modulation.
If you’re just not that into microcontrollers, you could build this digital IR theremin instead. If you find IR theremins soulless or plebeian, try this theremincello.
Continue reading “IR Theremin Speaks In Four Voices”
[Hlesliebole] wanted a finer degree of remote control over his time-lapse shots, so he decided to build an Arduino-driven infrared shutter. He ended up creating this killer Arduino-controlled photography rig that does a whole lot more.
This hack was built for [Hlesliebole]’s Nikon D3100, but he says it should work with any DSLR and remote shutter. This initial build uses an LED as a stand-in for the remote shutter that he ordered. He intends to update the post once it arrives and he integrates it.
[Hlesliebole] wired a 7-segment display to show the current time delay between photos. This can be set on the fly with a potentiometer, so there’s no need to stop and reprogram the Arduino. And while you’re grabbing a beer and watching the sun slowly sink, the rig can better capture that sunset because of a photoresistor. It detects the ambient light level and minimizes the number of throwaway dark shots.
If that weren’t enough, he’s built servo functionality into the code to support remote control over the camera’s physical position, allowing for panning or rotation over a scene. [Hlesliebole] doesn’t go into detail, but he assures us that there are many tutorials out there. If you think you’re man enough, you could always work in this outstanding versatile motion dolly hack.
Continue reading “Tricked-out Arduino-controlled Time-Lapse is More Than Just a Timer”
[Chris’s] bedroom has a unique setup with an air conditioning unit perched on the wall next to the top of the blinds that cover his window. Normally, to open the blinds he had to tug on a cord and operating the AC meant fiddling with a remote control. Not anymore. Now [Chris] has an all-in-one Raspberry Pi-based solution to drive both.
The build uses a stepper motor salvaged from a printer to directly drive the blinds, with a familiar-looking Easy Driver connecting it to the Pi. The motor spins the blinds’ mechanism either open or closed, though at a modest pace that’s slow enough to provide the needed torque. [Chris] added an IR diode plugged into the Pi that imitates the air conditioning unit’s remote control, and simply pointed it directly at the unit’s receiver. An inexpensive WiFi dongle gets the Pi onto the network, allowing [Chris] to interact via a custom web interface. The interface itself not only provides a couple of clickable buttons, but a cleverly-designed status image indicating the position of the blinds.
Make sure you see the video below for a demonstration and for more details on the build. This is one of the better examples of home automation devices we’ve seen recently, especially considering it actually fits the “autonomous” implications discussed in our Ask Hackaday post from a few months back—although a relatively simple automation, [Chris’s] interface does allow for operating both the blinds and the AC on a preselected schedule.
Continue reading “Raspi AC and Blinds Controller”
[Edward] wanted a different way to modulate notes on his MIDI controller, so he decided to go touchless. Inspired by the pressure-sensing modulation on his Edirol keyboard, [Edward] aligned eight sensors into a row of playable notes and used infrared to sense the distance of a player’s hand from the keys. He also included some function buttons to cycle through 10 octaves and RGB LEDs beneath the table that perform alongside the music.
He chose SHARP GP2D120 sensors (direct link to datasheet) for their low threshold, which allowed the board to detect distance close to the sensor. Each is mounted onto a sheet of frosted acrylic along with its own “hold note” button and an LED to indicate the key is playing. The lower panel houses an Arduino Mega that drives the system along with an RGB LED strip and its driver board. [Edward] used Maxuino and OSC-Route to interface the Mega to a Max/MSP patch which runs the show.
Learn more about the FlightDeck’s features in a video demonstration of the controller and the software after the break, then check out some other MIDI hacks like this organ pedal or the Arduino-driven MIDI sequencer.
Continue reading “FlightDeck: A “Touchless” MIDI Controller”
[Jeremy] refused to settle on your typical alcohol storage options, and instead created the Boozeshelf. Like most furniture hacks, the Boozeshelf began as a basic IKEA product, which [Jeremy] modified by cutting strips of wood to serve as wine glass holders and affixing the front end of a wine rack at the base to store bottles.
In its standard operating mode the Boozeshelf lies dark and dormant. Approaching it triggers a cleverly recessed ultrasonic sensor that gently illuminates some LEDs, revealing the shelf’s contents. When you walk away, then lights fade out. An Arduino Mega running [Jeremy’s] custom LEDFader library drives the RGB LED strips, which he wired with some power MOSFETS to handle current demands.
[Jeremy] didn’t stop there, however, adding an additional IR receiver that allows him to select from three different RGB LED color modes: simple crossfading, individual shelf colors (saved to the on-board EEPROM), or the festive favorite: “Dance Party Mode.” Stick around after the break to see [Jeremy] in full aficionado attire demonstrating his Boozeshelf in a couple of videos. Considering blackouts are a likely result of enjoying this hack, we recommend these LED ice cubes for your safety.
Continue reading “Interactive Boozeshelf is its own Dance Party”