Telling time by using the current position of the sun is nothing revolutionary — though it probably was quite the “life hack” back in ancient times, we can assume. On the other hand, showing time by using the current position of the sun is what inspired [Rich Nelson] to create the Day Cycle Clock, a color changing light box of the Philadelphia skyline, simulating a full day and night cycle in real time — servo-controlled sun and moon included.
At its core, the clock uses an Arduino with a real-time clock module, and the TimeLord library to determine the sunrise and sunset times, as well as the current moon phase, based on a given location. The sun and moon are displayed on a 1.44″ LCD which doubles as actual digital clock in case you need a more accurate time telling after all. [Rich] generally went out of his way with planning and attention to detail in this project, as you can see in the linked video, resulting in an impressively clean build surely worthy as gift to his brother. And if you want to build one for yourself, both the Arduino source code and all the mechanical parts are available on GitHub.
An interesting next iteration could be adding internet connectivity to get the current weather situation mixed into the light behavior — not that it would be the first time we’d see weather represented by light. And of course, simulating the northern lights is also always an option.
Continue reading “Decorative Light Box Lets You Guess The Time”
As you know, winter is coming. For a lot of people this means that Seasonal Affective Disorder is beginning to set in. [Luke]’s mom already has a light therapy box. It’s one of those commercially available ones that uses fluorescent bulbs and leaves a lot to be desired in the full-spectrum light simulation department. [Luke] jumped on the opportunity to design a better one.
The standard of quality for light therapy units is a rating of 10,000 lux. While lux definitely matters, the rating is a misleading selling point when given on its own. One of the other important factors in mimicking the sun is the Color Rendering Index (CRI). CRI is basically a rating of the bulb’s ability to imitate the color reproduction of natural daylight. The ratings run from 0 to 100 but in reality, the highest-rated bulbs of any kind top out around 98.
For all the fluorescent bulb-bearing light therapy units out there, those bulbs have pretty low CRI ratings. [Luke]’s project page provides emission spectra graphs for a number of bulb types, and we can see how his choice of ceramic metal halide bulbs stacks up against fluorescent, incandescent, and LED bulbs. One of the few downsides to this type of bulb is that they have long startup times.
He ended up making two light therapy lamps, one of them directional and the other omni-directional. They both use ballast-controlled ceramic metal halide bulbs. The ballasts are necessary to provide the high starting voltage that these bulbs require. The omni-directional light is built into a large hurricane candle holder. A lamp holder is fixed into the base and wired to an external ballast box. The directional lamp is a self-contained unit, and [Luke] is happiest with this one. It’s flat and rugged so it can be placed on top of a bookcase and the light bounced off of the ceiling for pleasant, indirect coverage.
We’ve seen a couple of alarm-clock wakeup light builds here, and we’re thinking this would make an awesome mashup.
[Flyingpuppy] sent us this tip about her cleverly-concealed pull-out lightbox drawer. Her resolution for the new year was to make more art, so she filled this coffee table with art supplies and decided she’d draw while relaxing in front of the television. She also wanted a lightbox nearby, which originally involved hacking the entire tabletop with some acrylic, but she eventually opted for a simpler build: and it’s portable, too! The drawer’s lights are battery-powered, so you can pull the entire thing out of the table and drag it onto your lap, if that makes drawing more comfortable.
[Flyingpuppy] sourced seven inexpensive LED units from her local dollar store, which she mounted to the back of the drawer with some screws. The rest of the drawer was lined with white foam board, the bottom section angled to bounce light up onto the acrylic drawing surface. Because she needs to open the case to manually flip on the lights, she secured the acrylic top magnetically, gluing a magnet to the underside of the foam board and affixing a small piece of steel to the acrylic. A simple tug on the steel bit frees the surface, providing access underneath. Stick around for a video below.
Continue reading “Built-in Coffee Table Lightbox”
[Paulo] needed to photograph small objects on the go. Since you can’t always depend on ambient lighting conditions he built a battery operated light box which is easy to take along on his travels.
We’ve featured portable light tents before, but they still tend to be a bit too bulky for his tastes. He chose to go with a white plastic storage container from Ikea. It’s lightweight, and acts as a diffuser for the light sources. Four strips, each hosting three LEDs, were mounted on the exterior of the container. Half of a PVC pipe protects the boards while providing a way to fasten the strips in place using nuts and bolts. The driver board and batteries find a home inside of a travel container for a bar of soap.
He likes the results, especially when a glossy white piece of paper is used as a top reflector.
[Kizo] repurposed a flatbed scanner to use as an exposure box for making printed circuit boards. Exposure time is controlled by an AVR ATtiny2313 microcontroller. The device is connected to a separate display board to control four 7-segment displays using one shift register for each. Time is set in ten second increments and once started, switches on the lights with a relay. Once the right exposure time has been reached, the lights are switched off and a piezo speaker is buzzed. There’s no mention of they type of bulbs he’s using but they look like compact fluorescent with tin foil beneath as a reflector.
If these are just CFL bulbs, how will the performance compare to a light box based around a UV light source?