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Topic: Remote Control Socket - Some Guidance? (Read 692 times) previous topic - next topic

Henry_Best

Xerosigma,

You can't power an Arduino directly off of the mains. You will have to use a wall wart or some other form of transformer/rectifier to power it.

You only need to switch the live [hot] wire that's going into the sockets. SWITCH OFF THE POWER TO THE SOCKETS AT THE FUSEBOARD! If you can, remove the fuse and put it in your pocket (to stop anyone else replacing it whilst you're working). Disconnect the live [hot] wire from the back of the sockets and connect it to the middle screw terminal on both of the relays. Be sure  any connections are well insulated. Next connect one of the other (normally open or normally closed) screw terminals on each relay to the live inputs at the back of the socket. Again, carefully check the insulation of every connection.

You may now restore power to the sockets. If you find that the sockets are not on (or off, whichever you want), you need to use the other output screw terminal of each of the relays. Don't forget to switch off the power first before changing them.

Make sure that all your mains wiring and the relay board are insulated. I suggest a plastic project box for the relay board with a hole to allow the mains cable out at one end and another hole, as far away as possible, to allow the low voltage control wires out. Keep the holes as small as possible to prevent 'fingerpokin'.

wizdum

If you want cheap wifi, you should look into the RN-XV modules:
https://www.sparkfun.com/products/10822

And an xbee Explorer to do the voltage conversion for you:
https://www.sparkfun.com/products/9132

You will need to put a pullup resistor on the DIN pin on the RN-XV module itself to make it work with the xbee Explorer.

These modules are not good for servers, since they can only handle 1 connection at a time, but they make great remote trancievers.
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PeterH

Yes, the mains voltage relay and a couple of wires solution shows how easy it is to make it work, but addresses none of the safety issues.


1: I most definitely do not understand the risks and how to address them. Would you be willing to share some knowledge?


Mains voltage is dangerous. If your product goes wrong, you could quite feasibly kill yourself or somebody else - either through electric shock or a fire. It is likely to go wrong in ways that you did not anticipate.

Your problem is to ensure that there is no failure mode that could connect mains voltages to any of the low voltage components, and that high and low voltages are physically as well as electrically isolated. In practical terms, the only sensible way for a novice to do this safely is to use a commercial component for the mains switching. A mains voltage relay is a good starting point and gives you electrical isolation, but you still have to deal with physical isolation of the circuits to and from the relay. If you use a PCB, you need to ensure that the high and low voltage parts are physically remote and sufficiently insulated from each other and that the high voltage part is fully insulated. If you use discrete wiring you need to ensure that the wiring is properly terminated into sockets and everything is mechanically secured.

While this is all doable, there is a very real danger that a novice tackling this problem will overlook something. By far your safest option would be to use a commercial product for the whole mains voltage part rather than try to design and build your own switch.
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zoomkat

You might wan to look at some of the x10 and home automation vendors to see what they have in the way of automated outlets. Might save on running a lot of wires. Also, search the forum for x10 information.
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