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Should I use a relay? Answered

Hello, I am trying to control a 9v DC pump with an arduino. I am thinking that I will need to attach a relay to the pump, and control the relay with a transistor from my arduino. Is this correct?

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user
steveastrouk (author)2011-09-01

Yes. Make sure you put a diode across the relay coil, tie the diode's cathode (the end with the marking) to the most positive side of the supply, and tie the anode to the top of the transistor/connection to the relay.

steve

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user

the diode is to make sure that no power goes back into the arduino?

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user
dog digger (author)2011-10-28

You could use a mosfet. Make sure you use a diode on terminals

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kenyer (author)2011-09-16

check this for nice schematics:

http://www.oomlout.com/a/products/ardx/circ-11

It helped me to understand relays.

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steveastrouk (author)2011-09-05

The diode stops a very high voltage that will be generated in the relay coil when its switched off from damaging the Arduino.

Steve

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