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Author Topic: there is a problem if i connect 5v relay to the digital output of arduino?  (Read 2215 times)
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kindly, i hv 4 of 5v relays connected to the arduino digital outputs...the relays
some times dont work if the DC supply voltage not fully charged ...so im thinking
of connect the relays on active LOW state...and supply from battry ==> 6v regulator ....so

6v ====>+ relay - <==== 5v arduino output pin (HIGH)    ====================>>>> relay OFF

so if output go LOW

6v ====> relay <===== 0v from arduino   ============ >>>>> relay switch ON

----------------------
there is a problem if i applyed 6v===><===5v   in OFF state?
-----------------------------------------------------------------------------------------
if i connect on active high  and use transistor for amplify arduino output ... there will be a problem with current or any other things ???

-------------- help me pls

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Not a good method. When the relay is commanded off the arduino output pin will be at +5vdc and the relay will be sending +6vdc to the output pin, bad results.

First before a proper wiring/powering method for you relay can be suggested we need to know how much current the relay coil uses when it's powered up.

Lefty
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Have a look at this tutorial
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i think this is the best method



thnx alot...
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It depends on the resistance of the coil.
If that is at least 150Ω (that'd result 30mA) then you don't need the transistor (but the diode is still required.) 
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