Arduino Compatible 5V Relay Board - General Electronics - Arduino Forum

I am having trouble with relay board and wonder if anyone could assist I have wired the relay supplying 5VDC from the Arduino Uno and switching from digital output. I am seeing a volt drop on the switch measuing 4VDC. When disconnected I have 4.8 VDC. The arduino is being feed from 9VC connector supply from a car battery through a 1Amp voltage regulator. If i connect the switch wire to Common 5VDC the switch will operate.

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