I'm not sure this is the right sub-forum, but it's the closest I can find.
So I have this project... I bought a Roomba 620 and being the low tier one, it doesn't have an scheduler to start on its own at a given time, so... Arduino to the rescue! 
(actually, an Adafruit RedBoard)
Now, this base should be heavy to keep the Roomba from accidentally moving it, so inside the box, I added a bunch of metal washers I had laying around, neatly stacked.
BUT I have an AC wire coming in passing just next to them, and I was wondering if that can cause any electromagnetic noise "or something". 
In the attached pic, the battery looking things are the stacks of washers and those are the mains voltage and the 5v wires.
I'm afraid to turn it on, honestly.
EDIT: added pic because the forum software didn't like the attachment for some reason.
The addition of a matchbox for example would be useful to give some example of scale
Sitting like that probably not a problem, HOWEVER, sooner or later someone will pick it up, turn it etc.and then you can end up with those washers in places you don't want them (see the "law of selective gravitation" http://www.murphys-laws.com/murphy/murphy-laws.html
Hi,
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Thanks.. Tom..
Use a brick glued to the base
I'm afraid to turn it on,
Don't be. If there is any problem it will not be a catastrophic one.
Boardburner2:
The addition of a matchbox for example would be useful to give some example of scale
Unfortunately I can't edit the post to add the link, but if you right click the image and open it in a new window/tab it will be bigger and clearer.
The red thing on the back is an Adafruit RedBoard, which is the same size as the UNO.
Size of washers are more or less the same as a coin battery (you can see the battery at the upper left corner where the clock module is).
Also, I turned it on. We'll see when I get home if the thing didn't blow up and the Roomba actually started.
gpsmikey:
Sitting like that probably not a problem, HOWEVER, sooner or later someone will pick it up, turn it etc.and then you can end up with those washers in places you don't want them (see the "law of selective gravitation" This site is temporarily unavailable
Whoever does that will have to remove the Roomba, or accidentally kick the it... and that's death penalty right there along with "don't touch my sister", "my momma is a saint" and that sort of things.
Also, if this thing works I guess I'll glue them so they don't move.
TomGeorge:
Hi,
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Thanks.. Tom..
No much to draw really, a 5mm IR led connected to pin 3 and ground via a couple of resistors to get to 660 ohms...
And the IR is controlled with the codes of this article (actually, the code from the comment by MadsH4): http://www.instructables.com/id/Super-Simple-Arduino-Powered-Roomba-Scheduler/step2/Wiring-everything-together/
Also, my code is a mess, I wrote it in one day, copied parts from other projects, and it's in Spanish. 
Hi,
Your pic in your first post has changed.
The reason you can't attach may be because of the image file size.
How are you powering the arduino?
Tom...
Cosme_Fulanito:
Unfortunately I can't edit the post to add the link, but if you right click the image and open it in a new window/tab it will be bigger and clearer.
The red thing on the back is an Adafruit RedBoard, which is the same size as the UNO.
Size of washers are more or less the same as a coin battery (you can see the battery at the upper left corner where the clock module is).
Also, I turned it on. We'll see when I get home if the thing didn't blow up and the Roomba actually started.
If i understand that picture correctly, it is the back of the docking unit.
The mains adapter is a separate unit.
I guess you just need weight.
How about a sock full of sand ?
I normally jut put a heavy bible ore something on the top of it.
Blu tack helps it from sliding off.
Here's a couple of pictures with proper exposure time 
and a soldering iron for size reference.
It must be more than one kilogram of washers for sure.
The good news is it didn't blow up and the Roomba actually started and cleaned.
The bad news is it moved a liiiiitttttle tiny bit... probably will be ok... but my paranoia will kick in at some point in the future and I'll bolt the thing to the wall I'm pretty sure.
Perhaps putting some small rubber pads on the bottom corners would keep it in place. It would take the weight currently displaced over what, 24sq in(?) and put that weight dispersed over 1sq in, plus the added friction of the rubber.
Hot melt glue is your friend.
So many people discussed! I have learned from all of you! ThenI'd like to buy OSCSMD-7050 to do some research too.
Ardino-Uno-Crystal:
So many people discussed! I have learned from all of you! ThenI'd like to buy OSCSMD-7050 to do some research too.
I am not sure i understand that.
You do realise that it is a fixed frequency device not variable ?
Other thing is the Roomba manual says it should be placed against a wall.
FWIW i use some of that sticky mat stuff which you can get to stop rugs wandering around.