App note from Richtek on how to work with Li-ion batteries properly. Link here
Lithium-ion/polymer rechargeable batteries, which have been widely used today, have distinguished properties, but are very delicate and have to be used with extreme care. Improper use of Li-ion batteries will bring about catastrophic consequences. The incidences of burning and explosions of Li-ion batteries have often been heard. Carefully understanding their properties and adopting a right battery management method is most essential for making good use of Li-ion batteries.
Dilshan Jayakody published a new build:
In this project we build simple I2S stereo decoder with amplifier. To decode I2S data we use Princeton Technologies PT8211 16bit DAC. KA2206 audio power amplifier is used as driver stage of this system.
Structure of this I2S amplifier is self-explanatory from the schematic. We select PT8211 and KA2206 combination due to lower cost and availability. Unfortunately PT8211 DIP package is not available in local market and we use SO package in our prototype. We design PCB for the DIP packages, and therefore we solder PT8211 SO package to PCB using “SO8 to DIP8” converter.
See the full post on his blog.
KA7OEI has a great write-up on building a transmit converter for 630 and 2200 meters:
As the name implies, a transmit converter takes another frequency – such as that produced by a conventional HF transceiver – and converts it to another frequency. In my case I use an FT-817 – a low-power (5 watt) all-mode, all-band transceiver that is a favorite for VHF, UHF and microwave enthusiasts that use transverters. Because of its small size, feature set and already-low output power, it is a natural to be used in this application.
See the full post on his blog.
Edward Mallon writes:
Dr. Beddow’s instrumentation class has been building the 2016 version of the Cave Pearl datalogger for more than three years, and feedback from that experience motivated a redesign to accommodate a wider range of student projects while staying within the time constraints of a typical lab-time schedule. The rugged PVC housing from the older build has been replaced with an inexpensive pre-made box more suitable for “light duty” classroom deployment. The tutorial includes a full set of youTube videos to explain the assembly. We hope this simplified build supports other STEM educators who want to add Arduino-based experiments to their own portfolio of activities that develop programming and “maker” skills.
Via the comments. More details on Underwater Arduino Data Loggers blog.
A detailed instructions of how to build this weather station project by Open Green Energy:
This Instructable is a continuation to my earlier weather station project. It was quite popular on the web, people around the globe made their own by following it and given valuable feedbacks for improvement.By taking consideration in to the comments and Q&A section of my earlier project, I decided to make this new version Weather Station.I also made a custom PCB for this project, so any one with little knowledge on electronics circuit can be made this project. My V-2.0 PCB can also be used for many application in Arduino platform. Following are the salient features of new weather station
Project instructables here.
An App note from OSRAM on an Intelligent control circuitry example using a PIC Microcontroller. Link here (PDF)
Nowadays, applications increasingly make use of LEDs as a replacement for traditional light bulbs. For example, LEDs are frequently used in the design of automobile tail lights, signal lights, traffic signals, and variable message signs.
LEDs provide several advantages over traditional light bulbs, such as smaller size and longer life. In many applications, the LEDs must be driven with intelligent control circuitry. According to the task at hand, this control circuitry must be able to fulfill various functions and tasks.
App note from OSRAM on thermal resistance for LEDs and IREDs (IR emitting diodes). Link here (PDF)
In order to achieve the expected reliability, lifetime and optimal performance of LEDs, especially for high-power LEDs, appropriate thermal management is of the utmost importance. One of the key parameters for good thermal management is the temperature of the active semiconductor layer designated as the junction temperature. The manufacturer’s recommended maximum junction temperature should therefore not be exceeded during operation, in order to prevent damage to the component. Ideally, the junction temperature should be kept as low as possible for the given application.
Due to the design principle of the LEDs, the junction temperature of the LED can not be measured directly.
Erich Styger has written an article on how to boot the NXP i.MX RT from Micro SD card:
It is a common thing to boot a Linux system (see the Raspberry Pi) from a micro SD card. It is not that common for a microcontroller. The NXP i.MX RT ARM Cortex-M7 fills that gap between these two worlds. No surprise that it features a ROM bootloader which can boot from a micro SD card.
Booting from a SD card is kind of cool: load a new software to the card, insert it and boot from it. In some applications this can be very useful: in my configuration the processor starts the ROM bootloader, then loads the image from the SD card into RAM and then runs it. In that configuration no internal or external FLASH memory would be needed.
Via MCU on Eclipse.
App note from Vishay on using chip resistors to achieve long-term stability. Link here (PDF)
Thin film chip resistor arrays consist of several resistors of equal or different values combined in one package. During the manufacturing processes and the device’s lifecycle, all the particular resistors virtually experience identical conditions, which allow the specification of their relative tolerances, relative temperature coefficients, and even a relative resistance drift. These relative parameters provide precise and stable resistance ratios and far better long-term stability of feedback circuits and voltage dividers compared to discrete resistors.