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Author Topic: Driving 4 LEDs and 4 Relays with a ULN2803?  (Read 673 times)
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BlueBill
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« on: November 18, 2012, 11:20:58 am »
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Any thoughts on problems driving (sinking) 4 LEDs on the 5V rail and 4 Relays on the 12V rail with the same ULN2803? (diode clamp on 12V rail)
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johnwasser
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« Reply #1 on: November 18, 2012, 12:01:17 pm »
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Since the 5V and 12V supplies go to the same Ground there should be no problem sinking either or both.
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« Reply #2 on: November 18, 2012, 06:28:18 pm »
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Yup, the diodes only needed on the relay windings so that should be fine.  Don't forget current-limiting resistors for the LEDs.
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