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I am using an Arduino and two relays to control 12V DC motor in both directions.

For the first trials it worked fine. Finally, my Arduino was fried on another direction swtich.

I think there is something wrong in the schematic. I believe that Arduino was killed by reverse voltage spike produced by motor.

Probably I need a diode across the motor. However, I have two directions here.

So, what is the proper schematic for my task would be?

Here is my schematic.

SCHEMATIC

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  • \$\begingroup\$ That is not a schematic, that is a wiring diagram. Anyway, post the code too. Most likely you control both relays simultaneously. Try controlling one relay first, then a delay until motor is stopped, and then the other relay. \$\endgroup\$
    – Justme
    Mar 9 at 19:25
  • \$\begingroup\$ please don't crosspost arduino.stackexchange.com/questions/81902/… \$\endgroup\$
    – jsotola
    Mar 9 at 19:36
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You can try this:

schematic

simulate this circuit – Schematic created using CircuitLab

Generally it's better to use a completely separate supply for the motors and to actually use the opto-isolation that is built into your relay module rather than bypassing it by tying the grounds together.

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You want to place EMI caps across the motor wires, as close to the motor as possible. Also, place a cap from each motor wire to the case of the motor. 0.1uF 50V ceramic should work fine.

On your Arduino to relay interface, make sure that there is a flyback diode across the coil.
See this question here for more info on the diode

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