In his video guide, [Ben] shows us exactly how to fit a standard solid state relay into a regular outlet box, and easily control it with an Arduino Uno. It even looks like there might be enough ...

That is why you must use an external power supply (Vcc) that is between 7 to 12 volts to power up the Arduino board and the transistor + relay. The load uses its own power supply, for instance if you ...

Though [David] could have easily used USB OTG for this project, many microcontrollers don’t have the USB-to-TTL capabilities of his Arduino – so this wasn’t entirely in vain. At first ...