a part of my project is to control electrical appliances using pc.

parallel port<mcu<electrical appliances ie: lamps,fans etc

a friend did almost the same project only that he uses led to demonstrate the appliances part where he needn't to consider 240V ac supply from ac mains. here is where i got it all confused.

1)how do we isolate the high voltage from mcu and pc?
-i googled around and found this. http://www.codeproject.com/csharp/control_...&select=1286423
It says opto coupler isolate the pc from ac power supply. How about the relay?i only heard about these two components over a year ago. so, complete noob here.

2) i want to add a dimmer circuit connected to my lamp/bulb.

pc>mcu>dimmer>lamp>ac mains

i should add an opto coupler between mcu and dimmer, no?


my primary concern is safety.So i need some assurance that this will not blow up on me. *Hee*

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Added on September 10, 2008, 8:44 pmhelp, anyone?

This post has been edited by sshlady: Sep 10 2008, 08:44 PM