Thanks for the interest. I did a little testing of the units I’m using.

They use 23mA in standby. I also checked how much power they consume and a plug-in energy monitor I have gives the standby power as 1.9 Watts and an in use (but without an appliance) power supply of 1 Watt (same current).

So they seem to use less current than Xbees but must be at a higher voltage, hence the surprising large power consumption. Obviously sleep and standby modes would be lower.

That said, if you are going to use Xbees you will need to power them from the mains at much a lower rectified voltage and that conversion process will probably cost you (powerwise, depending on how you go about it). So you’d have to take that into account.

Also you would have to manufacture each socket with the Xbees approach, which is both tedious and somewhat dangerous as you’re dealing with mains voltage. The approach I’ve taken here means you only have to tinker with the remote control (no high voltages and only on device, also you have consumer grade housings for your socket hardware).

As for hardware cost, all the hardware (3 remote sockets, a remote control, an Atmega8 and a CA-42 cable) in my approach costs almost the same as a single Xbee module (give our take a few euro/dollars).

If the issue is power costs, maybe if you do a really good job with the Xbees you might reduce the power consumption significantly. But the cost of hardware would take years to make them worthwhile (as compared to this approach). Also if you are concerned about multiple sockets draining power continuously you could consider a system where you use one socket in series with the others, so disabling the first in the series turns off the power to all the others, leaving only one on (although you have to watch the current draw here as the sockets I have can only draw a max of 10A).

That’s my comments on you’re options, I’m open to issues I may have over looked or glaring assumptions I’ve made.

Best of luck regardless,

Jake

I’m oscillating between doing this and something similar with Zigbee+relay modules…

BR

Someone was asking how to control a mains device safely from a Pi .

http://www.raspberrypi.org/phpBB3/viewtopic.php?f=37&t=7855&p=98065#p98065

( very cool work btw , for both yourself and the guy who started it )

Yeah, I’ve considered the use of the GPIOs on the Raspberry Pi and I’ll definitely look at doing something with them in the future (maybe add occupancy detection, so lights can be turned on/off when people enter/leave the room).

I suppose the plus of the approach here is that it’s more general and works across all devices with USB connectivity. For example I have a regular LAMP server at home and this method still works with it.

your design is very safe and does not depend on the computer used for the webserver, letting the microcontroller talk to the real world. Since the raspberryPi is equipped with GPIOs I guess you could have done without the FTDI cable and the arduino