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Author Topic: AC Lighting with Arduino  (Read 280 times)
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Hey All,

I've read all the other posts about this topic...but I'm an absolute novice and understood only about half of it.

What is the EXACT setup I would need to go from Arduino to a standard AC Light Bulb? The theory I'm looking for to start in like onKeyPressed("A") then light bulb turns on.

The project I'm looking to do requires lighting (at minimum) 12 AC lights...but not at the same time. I have 7'x7' walls with a scrim stretched over it. Depending of the variables of the room, I want the walls to light up red,blue, or yellow. I would like to have them fade between color modes.

Can anyone help me with this?
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Sussex UK / CT USA
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Sorry to be a bore... but having attended over a thousand emergencies as a firefighter, can I just say:

AC (mains) electricity can "bite" you hard if you make any mistakes. The "silliest" thing can have serious consequences.

===
Having said that...

In designing your project, be aware that dimming incadescant bulbs and dimming florescents (including the "green", "modern", "energy saving" "replacement" bulbs) require very different approaches.

Can you live with "on"/"off" for each bulb? At least for the first pass through your project? It will make your life a lot easier.

If you set up a socket which is turned on and off by a relay controlled by a low, Arduino friendly voltage, consider the merits of having the socket ON UNLESS the low voltage is SUPPLIED to the relay's coil. Such a device works fine as a simple extension cord (good for something, anyway!) at times when your Arudino control is either not working, or otherwise engaged.
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You might also want to consider interfacing with X10. It might cost more, but it keeps you away from the AC.
http://www.arduino.cc/en/Tutorial/X10
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There is a writeup here on how light dimmers work:

http://www.epanorama.net/documents/lights/lightdimmer.html

trying to summarise - you control the brightness by controlling the amount of the AC cycle that is allowed through to the bulb.

If you want an Arduino to do this (and it is possible, if not trivial), you will need to synchronise the Arduino code to the mains cycles (remembering that 50/60 Hz is no exact and can change up to 10% and any given time).

You contrl the brightness using a triac or thyristor. This would most safely be done using opto isolators.

As an alternative to dimming mains lights, there are a bunch of bright LEDs around which can be more safely controlled without using mains. Here is a link to a project that might give some ideas:

http://www.electronicsweekly.com/blogs/gadget-freak/2008/02/pete-decided-to-give-his-lamp.html#more

Mike
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