Maximum consumation Arduino

[alexglowee]

Thanks for your answer.

@Paul_B

The "Vin" terminal - or the "barrel jack" is simply useless for any serious project.

You need a 5 V regulated supply to power the Mega and all your 5 V devices. Connect the 5 V to the "5V" pin except when connected to a PC via USB.

Hum ... We use the VIN because We read you can't use the USB port and the 5V is the same time. Well, we use USB for the communication between the rasp and our board, and sometimes to read data without going through the Rasp. I think it's possible to use some Arduino pin instead of USB but I don't know how it works.

@Paul_B

A relay module - which you need in order to control the relay from an Arduino pin - includes a transistor as well as a diode to suppress "kickback" from the relay coil itself. If you are using the relay to control a solenoid (with DC - AC is a different matter) then you really should have a diode across the solenoid coil. You certainly need one with the FET module you cite, as best I know (because it is not properly documented) it does not include one.

Okay, so my relay is not as good as I thought. Do you know any references for well-manufactured relay modules?

Kind regards,

Alex