App note from Würth Elektronik on why plants evolved to use far-red wavelengths and why it is essential for them. Link here (PDF)
The light requirement of plants is now known to be far more complex than originally thought leading to the development of numerous LED technologies that produce a variety of different light spectra, both monochromatic and polychromatic.
Far-red encompasses wavelengths 700 – 800 nm, a region of light that is on the edge of visibility in humans. However, these wavelengths have been proven to result in faster growth, increased biomass and better sensory characteristics (e.g. smell, taste, texture, color).
This is real-time clock based automatic LED lamp which we originally designed to use as night light. This lamp can programmed to turn on and off at the specific time of the day. For example, it can program to turn on at 6 PM on each day and to turn off at 4 AM next day.
The core component of this project is PIC16F883 MCU and it’s firmware is developed using MikroC Pro for PIC. We select this MCU because of it’s 7 KB flash memory, I2C, UART, E2PROM and built-in 8-bit and 16-bit timers.
Another app note from Holtek this time about their HT66FB574, a USB keyboard device that can support single color LED streamer. Link here (PDF)
The video gaming industry is seeing continual increasing demand for multi-feature keyboards. These can include features such as keys with an individual LED which can display different graphical effects along with variable illumination levels. With each key having an illuminated surrounding area effect along with multiple colour and pattern changes, this allows for a more colourful and stimulating gaming keyboard.
Light guide basics app note from OSRAM. Link here (PDF)
Light Guides are used wherever the light of a light source should be distributed homogeneously over a particular area, when there is a spatial distance between light source and the area which is to be illuminated.
The cheap price however comes with a few niggles, namely getting it up and running in the first place with the limited documentation. Gnarly Grey do a great job of explaining programming a starting program but don’t say much about further development. With that in mind, I’m going to run through the methodology of getting an LED flashing using VHDL. There seem to be a fair few Verilog methods but not many people seem to have touched upon VHDL with these FPGAs.
LEDs used in a controlled environment greenhouse farms, an app note from Würth Elektronik. Link here (PDF)
Greenhouse farms may not be a new technology but with an every growing world population and the move towards sustainability, intensive yet highly efficient and standardized food production will increasingly become the norm in future years opening a potentially huge new agricultural sector that incorporates the latest technologies from the bioscience and engineering fields. But how can researchers and personnel from these separate fields understand the mutually dependent requirements of indoor greenhouses? Photosynthesis is the process that converts water and carbon dioxide into complex carbohydrates (i.e. sugars) and oxygen using energy from light. However, although the energy radiated by the sun that reaches the earth’s surface consists of the entire spectrum of visible light (and more), plants only utilize specific frequencies of light for photosynthesis. These frequencies are related to the absorption characteristics of different pigments that are present within organelles called chloroplasts that are responsible for different functions of photosynthesis.
Light emitting diodes are solid-state, light generating components that, have become and will continue to be one of the greatest drivers in the expansion of internal greenhouses due to their advantages over incandescent bulbs, fluorescent bulbs, high-pressure sodium lamps and mercury lamps. Their main advantage stems from their ability to generate specific wavelengths of light. To meet the requirements for Horticultural LED’s for Indoor-farming, Würth Elektronik offers the WL-SMDC SMD Mono-color Ceramic LED Waterclear series of LEDs. The WL-SMDC range has been expanded to include wavelengths of 450 nm (Deep Blue), 660 nm (Hyper Red) and 730 nm (Far Red), which have been selected to match the absorption spectra of photosynthetic pigments. In addition to the existing products in the range, a diverse range of combinations is possible that can be catered to the target cultivar.
Upon removing the glass bulb enclosure, I was a bit surprised to see that only two power LEDs were used in this Cree bulb. Typically, you would see many more lower wattage LEDs put together to achieve higher wattage ratings. The two power LEDs are wired in series. Each power LED likely consists of eight to ten LED dies inside as the forward voltage drop of these two LEDs is measured at around 70V in operation, with each dropping around 35V. There is also a reverse polarity protection diode integrated into each of these power LEDs.
Gelstronic shared detailed instructions of how to build this 3D POV display, project instructables here:
In my project i use a spinning helix of LED strips. There are a total of 144 LEDs that can displays 17280 voxels with 16 colors. The voxels are arranged circularly in 12 levels. The LEDs are controlled by only one microcontroller. Because i have used the APA102 LEDs i need no additional drivers or transistors. So the electronic part is easier to build. Another advantage is the wireless electrical supply. You need no brushes and there is no friction loss.
I usually assemble by hand all the boards I make. I use SMD components, especially in 0805 format for resistors, capacitors and leds. With the last ones, I always have the same problem: I need to check the polarity of it, to ensure that I assemble on the right way. To do it, I need the multimeter, select the diode position and test the led’s for the right polarity. Because on the assembly process I don’t usually the multimeter, why don’t make a tweezers to test the led’s? It’s an easy and very cheap project, and you’ll have a usefull tool when assembly boards. Here’s the result, after a couple of hours working on it ;).