App note: Active cell balancing in battery packs

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Cell balancing implementation from NXP Semiconductors. Link here (PDF)

Batteries made of multiple cells connected in series are often used as a power source for common electronic devices. In multicell battery chains, small differences between the cells (due to production tolerances or operating conditions) tend to be magnified with each charge or discharge cycle. In these situations, weaker cells are overstressed during charging, causing them to become even weaker, until they eventually fail and cause a premature failure of the whole battery. Cell balancing is a way of compensating for these weaker cells by equalizing the charge on all the cells in the chain, thus extending the battery life.

Aweigh: the open-source alternative to GPS

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A team of student designers and engineers from the RCA and Imperial College have developed a substitute for GPS that does not rely on satellites, called Aweigh:

Aweigh is an open navigation system that does not rely on satellites: it is inspired by the mapping of celestial bodies and the polarized vision of insects. Ancient seafarers and desert ants alike use universally accessible skylight to organize, orient, and place themselves in the world. Aweigh is a project that learns from the past and from the microscopic to re-position individuals in the contemporary technological landscape.

Via Open Electronics.

Check out the video after the break.

Homebrew DMX-controlled RGB LED light

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Glen has written an article detailing his homebrew DMX-controlled RGB LED light:

This project is a small DMX-512 controlled, color-changing RGB LED light. The light can be controlled via the DMX512 protocol or it can run a number of built-in programs depending on how the software is configured. The light incorporates an advanced 16-bit PIC24 microcontroller with PWM capabilities, a 3D printed enclosure, a laser cut acrylic lid, a custom switching power supply, and a MEMS oscillator. The light measures roughly 2.25″ square by 1.25″ high. This light is the evolution of my RGB LED light designs that span back over a decade.

Project info on Photons, Electrons, and Dirt blog.

Arduino Shield for CAT M1 and NB-IoT modems

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Michael Krumpus designed and built an Arduino shield for Nimbelink Skywire CAT M1 and NB-IoT modems, that is available on Github:

Nimbelink has a development kit for use by product developers, but it’s rather expensive. I wanted to try out a Nimbelink CAT M1 modem without the dev kit, and since there are so many hobbyists using Arduinos out there, I wanted to provide a nice Arduino library for the modem. I chose the Nimbelink module based on the Sequans Monarch CAT M1 modem and got to work designing an Arduino shield to hold it.

More details on Nootropic design Project Lab site.

App note: Reduced power dissipation of relay loads

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Another app note from ON Semiconductors on using PWM technique to reduce power consumed when latching mechanical relays. Link here (PDF)

Integrated circuit driver circuits often use relay loads in their application. Output drivers are a source of power dissipation on the IC. Latching relays can be used to keep sustaining load current at a minimum by engaging and removing drive current, but a PWM system can also preserve reduced power conditions by engaging and reducing duty cycle using standard type relays.

By considering the Maximum Turn−On Voltage and Minimum Turn−Off Voltage specifications typically quoted in the relay electrical specification, your system design can utilize a signal to pull−in and activate the relay followed by a reduced power PWM sustaining signal.

App note: The load switch – Selection and use of ecoSWITCH(TM) products

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ecoSWITCH(TM) from ON Semiconductors offers space saving solution on power distribution system. Link here (PDF)

Load switches play an important part in the management of supply domains and the protection of the loads they supply. Loads switches are often used for power sequencing, standby load leakage reduction, and inrush current control. Integrated ecoSWITCH products deliver an area reducing solution, offering over current protection, load soft start, and extremely low on series resistances of sub − 20 milliohm. This article discusses the primary benefits of load switches, application considerations, and how ecoSWITCH differs from other types of integrated switch offerings. A generic cloud system application and USB power delivery example are presented to demonstrate how the addition of ecoSWITCH solves design challenges such as achieving low quiescent current, local load protection, and startup sequencing.

PIC16F1459 USB stack light controller

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Glen Akins published a new build:

After using the PIC16F1459 to build numerous USB HID input devices including a giant keyboard, a tiny keyboard, and a big red button, it was time to see if the PIC16F1459 could be used to control outputs too. Sticking with the industrial theme, I chose to build a USB controller for a, um, stack of industrial stack lights.

See the full post on Photons, Electrons, and Dirt blog.

WiFiChron alarm clock

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Here’s a cool WiFiChron clock with 8-character alphanumeric LED display by Florinc:

For WiFiChron, two cascaded modules make an 8-character display functionally similar to HDSP-2534, but bigger and more visible. With the “Display Abstraction Layer” already in place, software support should be easy to integrate, since controlling it with the HT16K33 breakout allows the re-use of the above mentioned Adafruit LED backpack library. For maximum compatibility, I followed the same wiring, then connected the two extra segments, A2 and D2, to pin 10 (not connected for the 14-segment backpack) and pin 11 (connected to the DP), respectively.

More details on Wise time with Arduino blog.