This is an example of a simple and cheap milliohmmeter that can be made by every maker. The core of the circuit are a current source (LT3092) and a current sense (INA225): a costant current flows through the milliohm resistor under test and the voltage at the current sense output gives the value of the resistor (V=R*I). Continue reading
Nowadays almost every electronic gadgets are powered or recharged by a USB port (full size, mini o micro) as well as many of consumer products we use every day, including our smartphone. To recharge or give power to such products, there are many portable rechargers which have a rechargeable lithium battery and the electronics necessary to convert the battery voltage to 5V and to recharge the internal cell. The cost of these smart chargers is very affordable but we’re hardware makers, aren’t we? So why don’t to do it by ourselves to give power to our Raspberry Pi, arduino or Beaglebone black? We’ll show you a possible way to design one of these intelligent portable power supply. 
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Microchip: Application Notes- TB3205A - PIC16(L)F19197 LCD Bias Generation and Contrast Control Using the Internal LCD Charge Pump
- TB3203A - Real-Time Clock and Calendar (RTCC) with Battery Backup for the PIC16(L)F19197 Family Devices
- TB3193 - Active Clock Tuning for PIC16(L)F191XX Family
- AN2543 - Temperature Logger with ATtiny817 and SD Card-v2
- AN2548 - AVR42779: Core Independent Ultrasonic Distance Measurement with the tinyAVR 1-series
- Open Electronics
- mbed