Arduino Forum

Using Arduino => General Electronics => Topic started by: t3rror23 on Feb 01, 2013, 11:40 pm

Title: varying high voltage
Post by: t3rror23 on Feb 01, 2013, 11:40 pm
hey guys...I live in South Africa so we use 220V-240V AC. Im looking for ways to to interface the arduino with such power sources for things like home lighting. Basic on and off is fine but my biggest problem and focus is accomplishing a dimming function. what are my options as far as thats concerned?

Thanks in advance:)
Title: Re: varying high voltage
Post by: Krodal on Feb 01, 2013, 11:44 pm
What would you like to dim ?
Lights ? What kind of lights ?
Title: Re: varying high voltage
Post by: t3rror23 on Feb 01, 2013, 11:50 pm
i currently have  2W led down-lights but i will replace them accordingly with dim capable ones.
Title: Re: varying high voltage
Post by: t3rror23 on Feb 01, 2013, 11:53 pm
i was also thinking of controlling the speed of my high velocity fan
Title: Re: varying high voltage
Post by: dhenry on Feb 01, 2013, 11:53 pm
Quote
2W led down-lights


They are fairly (read: very) difficult to dim.

If I would you, I would start with regular incandescent light bulbs: you can dim those things easily with a bridge rectifier + mosfet, if you are OK with floating the whole dimmer.
Title: Re: varying high voltage
Post by: t3rror23 on Feb 01, 2013, 11:57 pm
if by floating you mean putting it in the ceiling then yes thats fine!! im not completely clued up with electrical components so which mosfet type should i look for?
Title: Re: varying high voltage
Post by: dhenry on Feb 02, 2013, 12:02 am
Quote
im not completely clued up with electrical components


In that case, don't work on mains.

Try something simpler / safer.
Title: Re: varying high voltage
Post by: lemming on Feb 02, 2013, 12:08 am
Have a look at :

http://arduino.cc/forum/index.php?topic=51671.0

You will need to use incadescent lights for this circuit and do your homework. These are lethal  voltages.
Title: Re: varying high voltage
Post by: t3rror23 on Feb 02, 2013, 12:10 am
i acknowledge the risk involved but i meant specifically the mosfet needed. applying it is no problem...in addition i found this just now online: (http://www.instructables.com/files/deriv/FO4/P488/H3CS2YL2/FO4P488H3CS2YL2.LARGE.gif)
although the site disclaims that users said it was unsafe. is this true or just for legal purposes?
Title: Re: varying high voltage
Post by: dhenry on Feb 02, 2013, 12:13 am
Quote
i found this just now online:


That's the basic structure.

Quote
is this true or just for legal purposes?


It is true.
Title: Re: varying high voltage
Post by: lemming on Feb 02, 2013, 12:14 am
No. Use an optoisolator as used in the thread that I posted.  If there is a problem with the circuit, you are less likely to have 240VAC feeding back into the user.
Title: Re: varying high voltage
Post by: t3rror23 on Feb 02, 2013, 12:19 am
Okay...thank you so much for the help...i shall start there:)