Smart Battery Charger


gfwilliams @ has build a smart battery charger that is able to individually charge each battery , automatically discharge them and give you an idea of their capacity. The charger is controlled by an Espruino Pico and results are displayed on a Nokia 5110 LCD display.

If you’re anything like me you’ll end up with a lot of rechargeable batteries, none of which end up being charged properly, and some of which turn out to be completely unusable. It’d be perfect if you had a low-power battery charger that you could leave on all the time, that would charge your batteries individually, automatically discharge them, and give you an idea of their real capacity. That’s what you’ll make in this tutorial!

Smart Battery Charger – [Link]

Staff with Click Sound and Obstacle Alarm

People who are visually impaired usually use a staff to guide them as they walk. They tap with their staff to know if an obstacle is present around. Others use the echolocation technique. They produce a clicking sound through their tongue, foot, and fingers and through this they detect objects from their surrounding by sensing the echoes produced.

The design above is a simple project that aims to assist visually impaired persons by having a staff that produces a beep/click sound that they can use for echolocation and also has an ultrasonic sensor that alerts the user if there is an obstacle ahead. Inside the handle of the staff, the control circuit is located. Below it, the speaker is positioned facing front to release in a forward direction the beep/click sounds for the user to sense what is ahead. The speaker is connected to PWM pin of the microcontroller to produce sound. An ultrasonic sensor is located at the base of the staff. It is connected to an interrupt pin of the microcontroller. The continuous beep/click sound is replaced by an alarm sound when the sensor detects an obstacle. With this, additional aid is provided to the user especially to those who are not trained to be capable of echolocation. The base circuit and the control circuit in the handle are connected through the use of 179840-1 and 177900-4 Power Double Lock from TE Connectivity. These are headers and crimp housing connectors that provides durability to the design. The feature locking capability that secures the mating of the circuits connected together.

The design is operated with a +5V battery and has a switch to ON/OFF the circuit. The project is programmed to detect objects half meter and below. Beyond this range, the design will not alarm for the user to have a lesser restriction in moving. With this design, visually impaired users don’t have to tap their staff hard, which could hit someone or something.

Staff with Click Sound and Obstacle Alarm – [Link]

AC Solid state Relay for Inductive Load



AC Solid state Relay for Inductive Load offers simple On/Off type Switch Control with TTL compatible input signal.

  • Input signal : 2 ~ 5 VDC, TTL compatible
  • Output : up to 500 W
  • Mains supply input 230 VAC or 110 VAC
  • Optically isolated Triac based design
  • Power Battery Terminal (PBT) and Terminal pins for easy input / output connection
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 35 mm x 72 mm

AC Solid state Relay for Inductive Load – [Link]


Atmega32u4 Breakout Board Tutorial

microcontrollers_296-01 has published a new tutorial for their Atmega32u4 breakout board. It discuss on how to use it with AVRdude and how to setup and use it with Arduino IDE.

We like the AVR 8-bit family and were excited to see Atmel upgrade the series with a USB core. Having USB built in allows the chip to act like any USB device. For example, we can program the chip to ‘pretend’ it’s a USB joystick, or a keyboard, or a flash drive! Another nice bonus of having USB built in is that instead of having an FTDI chip or cable (like an Arduino), we can emulate the serial port directly in the chip. This costs some Flash space and RAM space but that’s the trade-off.

Atmega32u4 Breakout Board Tutorial – [Link]

Quick Arduino Hygrometer with OLED display


jazzycamel @ has published an Arduino based Hydrometer with OLED display. It uses an Arduino Leonardo Pro Micro, an Adafruit SSD1306 OLED display and DHT11 digital temperature and humidity sensor.

We have been having some condensation and mould issues in our apartment recently due to, I think, the humidity levels. Our property is relatively newly built and, as such, has very good insulation properties (double glazed windows etc.).

Quick Arduino Hygrometer with OLED display – [Link]

Starling – WiFi enabled LED Display


Starling is a modular, Open Source LED display with WiFi connectivity. It comes with a mobile app for easy configuration and usage and has hardware support for Bluetooth.

The LED matrix is driven by an Atmega8 microcontroller (MCU), instead of a standard ASIC. This provides a lot of flexibility in the firmware. The firmware detects and assigns IDs to newly plugged-in modules. The microcontroller also stores font tables; hence if ASCII is sent on the serial (UART) port of the MCU, ASCII is what will be displayed on the matrix. Since the firmware detects adjacent displays, it can easily decide if it needs to display static or scrolling text.

Starling – WiFi enabled LED Display – [Link]

OpenSource Arduino OLED Clock with temperature measurement


Konstantin Dimitrov has published his Arduino OLED clock which uses DS1307 real time clock module and TMP102 temperature sensor that communicate through I2C.

This clock will not only show you exact time and date but also it will show you the ambient temperature in both Fahrenheit and Celsius, with accuracy of 0.5°C (-25°C to +85°C) and with resolution of 0.0625°C. The pages are changing on every 10 seconds, but you can change that.

OpenSource Arduino OLED Clock with temperature measurement – [Link]

Wi-Fi and OLED Upgrade for MightyOhm Geiger Counter


Dan Watson @ wanted to have more fun with his MightyOhm Geiger Counter so decided to add an OLED display and Wifi capability to it. To achieve that he modified the counter, added a Feather HUZZAH ESP8266 with OLED FeatherWing and wrote some code. The process is documented on his blog:

I assembled my Geiger counter kit from MightyOhm some time ago. It’s a very fun kit and the finished counter looks awesome. Oh, that Geiger-Muller tube sitting on that yellow PCB! I’ve always wanted to modify it somehow and add functionality. Today I realized that an Adafruit Feather sits PERFECTLY where the AAA battery holder normally goes. Doesn’t it look like they belong together?

Wi-Fi and OLED Upgrade for MightyOhm Geiger Counter – [Link]

Home Built Bench Power Supply using ATMEGA328P

PSUfront has designed a nice power supply based on  ATMEGA328P and Arduino bootloader. The output is dual channel 0-24vdc @ 3A each, with preset constant current and independant voltage/current control.

This isn’t a full design blog but I’ve tried to document/add stuff as I go along, the idea being I’ll put all design documentation (schematic, partslist, Eagle PCB files, wiring diagrams etc) when it’s all finished.

Home Built Bench Power Supply using ATMEGA328P – [Link]

LTC4123 – Low Power Wireless Charger


Linear Technology Corporation introduces the LTC4123 to further expand its offerings in wireless battery charging. The LTC4123 combines a 30mW wireless receiver with a constant-current/constant-voltage linear charger for NiMH batteries, such as Varta’s power one ACCU plus series. An external resonant LC tank connected to the LTC4123 enables the IC to receive power wirelessly from an alternating magnetic field generated by a transmit coil.  Integrated power management circuitry converts the coupled AC current into the DC current required to charge the battery. Wireless charging with the LTC4123 allows for a completely sealed product and eliminates the need to constantly replace primary batteries. Zn-Air (Zinc-Air) detection allows applications to work interchangeably with both rechargeable NiMH batteries and primary Zn-Air batteries with the same application circuit. Both battery types can directly power a hearing aid ASIC without the need for additional voltage conversion. By contrast, a 3.7V Li-ion battery requires a step-down regulator in addition to the LTC4123’s functionality to power the ASIC.

LTC4123 – Low Power Wireless Charger – [Link]