How to have external power to a relay module?

Other Hardware Motors, Mechanics, Power and CNC
1

Hello. I'm wondering how i would power a 5v relay module besides powering it from the arduino.
This is the relay module I got: http://www.ebay.com/itm/131143451377?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649. The reason I want to do this is because I already have a relay module connected to the arduino and I want to control another on. Thanks in advance.

2

See http://arduino-info.wikispaces.com/arduinopower

Your relay board features optical isolation so that section would be pertinent to your requirements.