[Trent M. Wyatt]’s CPUVolt library provides a fast way to measure voltage using no external components, and no I/O pin. It only applies to certain microcontrollers, but he provides example Ar… ...

Looking for practical Arduino projects? This guide shows how to control a relay from your smartphone using an Arduino Uno — ...

You can use a 6V to 20V unregulated external power supply, but the recommended range for the Nano is between seven and 12 volts only. To be safe and prevent any damage to your board or components ...

It has 250V / 5A Relays Outputs, 2A Digital Outputs, and Digital/Analog inputs and outputs, just like a regular Arduino, but everything is amped up.

Power Supply (5-12V) and External Battery connector The UDOO has been in development for more than a year, and the team says it is "80 percent ready" to deliver the final product.