Relay in Arduino

Hi, How can I use relay in Arduino to switch between 2 voltage sources, like solar panel and 9V battery? Any answer is welcome.

by Ahmed_Fakhouri
August 30, 2021

Arduinos can deliver 5 volt, but with limited amount of current. So you will need a dual pole relay which can turn on well under 5 volt on the command side, with a limited current (and flyback diode to eventually protect the Arduino against back EMI). Alternatively, you can use two single pole relays, and be sure that the two are not active at the same time.

You can also use a circuit where the 9 volt source acts as an automatic backup of the main source, the solar panel. Although that I suspect that solar panel vendor already supplies such a tool in their commodities in accordance to eventual specific requirements for their panels.

by vanderghast
August 31, 2021

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