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Sorry I'm new to electronics while I've some experience in coding. This let me very curious about the Arduino Due board: it is super powerful and I can run some C++ code that I can not with the normal Arduino Uno. But I lack in electronic theory, sorry if the question is a little bit dumb.

Can I drive this shield with an Arduino Due? The Due board is at 3.3V while the relays in the shield are at 5V.

What do I need to make them run smoothly?

Actually I'd like to run 5 of those shield with only one Arduino Due board. Do I have some problem with power supply?

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You'd have to remove the yellow jumper. Connect 3.3v to the VCC and 5v to the JDVCC. But please double check that JDVCC is connected to one side of all the relays.

This way the opto-couplers are activated by 3.3v signals, which in turn activate the transistor (5v) used to engage the relay.

  • just in case that JDVCC is NOT connected to one side of all the relays? But anyway, how did you understand which kind of optocouple are in the shield? – nkint Dec 22 '14 at 15:06
  • If not, switch the 3.3v and 5v. Most relay boards use the same circuit. Also the optocouplers are kind of easy to spot. – Gerben Dec 22 '14 at 20:43
  • Sorry but why can it work? Those relay are 5V relay.. why I don't need any extra transistor? and then, are you sure I can drive 20 relay simultaneously from one Arduino Due? Only 130mA for all the digital i/o – nkint Dec 22 '14 at 20:49
  • No need for any additional hardware. If you look closely at the board, you can see there is already a transistor in place (Q4, Q5 and Q6 in the image). This transistors and relays are powered with 5v. The 3.3v digital I/O is only used for the optocoupler and the indicator led, so only a few mA. – Gerben Dec 22 '14 at 21:33

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