Instead of controlling his temperature and humidity display directly, maker Zaphunk did things a bit differently, driving the temperature of each segment with a Peltier element, or thermo-electric cooler (TEC), to change its color.
Each segment is made out of a thermochromic material, cycling from a black off state to a greenish hue when on, for a device that can—somewhat ironically—show the temperature by changing its temperature.
Ambient conditions are read via a DHT22 sensor, and everything is controlled by a half-dozen Arduino Nanos. This number boards were needed in order to power the nine dual motor drivers that handle the Peltier elements, each of which require two PWM outputs, along with 5 IO pins.
Apparently not content with a traditional laser harp, Jonathan Bumstead set out to take things in a different direction. What he came up with is a device whose laser strings are arranged horizontally, and loop though its boxy structure for an amazing audiovisual effect.
The aptly named Upright Laser Harp is divided up into six rows, which each contain two laser/photoresistor pairs for an instrument total of 12 notes. Each laser is reflected once before hitting its photoresistor to wrap the entire structure in light, and values are sensed by an Arduino Mega as note inputs. Sounds are then generated by an Adafruit Music Maker Shield, and different MIDI instruments are selected with a rotary switch and a stepper-based electromechanical display system.
Laser harps are musical devices with laser beam “strings.” When the beam is blocked, a note is played by the instrument. Usually laser harps have the beams travel vertically in the shape of a fan or vertical lines.
In this project, I built a laser harp with stacked laser beams that propagate horizontally. The beams reflect off mirrors to form square shaped beam paths. Instead of a MIDI output like my previous laser harp, this device has built-in MIDI player so the output is an audio signal. This means the device does not have to be connected to a computer or MIDI player (e.g. keyboard) to play sound. Both built-in speakers and audio output jack are available for playing music.
Be sure to check out the mini-concert and build details in the video below!
The setup uses 16 pairs of IR emitter and receivers arranged down the length of the bi-color 16×32 matrix to tell when one has inserted a finger or other object into an area. When sensed, it changes the corresponding column on the display from red to green or back again.
An Arduino Mega is used for overall control of the device, along with shift registers and multiplexers/demultiplexers to account for the massive amount of IO needed.
How to build a night vision camera, video showing the process and problems that I came across when building this camera
Raspberry Pi night vison camera
Built into the body of an old camera flash, Dan’s Raspberry Pi night vision camera is a homage to a childhood spent sneaking around the levels of Splinter Cell. Says Dan:
The iconic image from the game is the night vision goggles that Sam Fisher wears. I have always been fascinated by the idea that you can see in the dark and this formed the foundation of my idea to build a portable hand-held night vision piece of equipment.
The camera, running on Raspbian, boasts several handy functions, including touchscreen controls courtesy of the Pimoroni HyperPixel, realtime video and image capture, and a viewing distance of two to five metres.
It’s okay to FAIL
Embracing the FAIL (First Attempt In Learning) principle, Dan goes into detail about the issues he had to overcome while building the camera, which is another reason why we really enjoyed this project. It’s okay to fail when trying your hand at digital making, because you learn from your mistakes! Dan’s explanations of the struggles he faced and how he overcame them are .
Good read on this app note from Silicon Labs comparing their low power but obsolete timer. Link here (PDF)
The 555 timer is the workhorse of ICs, with close to a billion of them manufactured every year. Introduced in 1972, the 555 is still in widespread use because of its ease of use, reasonable price, and good stability. It can be found in a wide variety of applications for oscillation, timing and pulse generation. But what if you need a timer IC for ultralong life, low-frequency battery-powered/portable applications where a low supply current is a requirement? Is the CMOS555 timer your best option?
Q-pump an alternative to inductor charge pump boost regulator for low power and sleepy microcontroller from Silicon Labs. Link here (PDF)
In the switch-mode power supply world, capacitor-based charge pumps (or Q-pumps) generally aren’t useful for heavy lifting, but work well in niche micropower applications where space is at a premium. They work best in applications where the output voltage is an integer multiple of the input voltage, which are operating points that result in peak efficiency. However, they can also shine when powered from a variable input like a battery, particularly when quiescent battery drain is more important than heavy-load efficiency. This might be the case when powering a microcontroller that spends most of its life sleeping.