How can one control AC power (220V) with a Raspberry Pi?

Question

I though about using the Raspberry Pi to switch on and off other electrical devices which unnecessary consume power in stand-by mode. In short, I'd like to control an AC socket or multiple sockets. How can one let the computer "push the button":

Image: CC-BY-SA 3.0 by Firstfreddy

The physical solution is a relay, but I don't want to build all on my own and play around with 220V and sparks when switching on and off ;-) By the way the Raspberry Pi requires 2 Watt in idle mode, so only using it as a switch to save energy might not make sense, so it should be usable for other purpose at the same time.

Answer 1

Well you could use a Solid State Relay which is much smaller and easier to control than a mechanical relay, using an MCU or in this case Pi's GPIO pin.

You have to drive the input pin constantly to keep the relay on (just like a mechanical relay) So if something fails with that signal then the power goes off. To avoid that you going to have to design another circuit that can self sustain itself.

But you can get these pretty cheap on eBay and they are completely safe (isolated) so they wont blow up the Pi and do not require allot of power to drive them about 3~10mA - Just check the details before buying one. It is also worth noting they can heat up if you load them heavily (close to the maximum rating)

* * * WARNING * * *

• Switching mains involves interfacing with potentially lethal voltages. Due care and competence is required. Death is possible. YMMV. _{This paraphrases Russell McMahon's advice on Electrical Engineering}

Answer 2

You could get one of these (RF) remote control power switches (Assuming you can find one suitable for your local power receptacles)

and hardwire the RPi to the remote. This has the advantage of being isolated and not requiring any mains wiring. You'd have to take into consideration the power consumption of the device if the goal is to save power.

Answer 3

You can get a certain power suply with a USB-Connection and control it with this http://sispmctl.sourceforge.net/ Debian/Raspian has the package sispmctl by default.

Answer 4

you could also use an existing device. I have interfaced an Aviosys NetPower 8800 switch which connects via USB.

It didn't come with Windows drivers and they weren't willing to nrelease an interface spec so I could build a Linux driver.

But I've written a Python program to control it:

https://skydrive.live.com/#cid=500667A62B4F909A&id=500667A62B4F909A%21294

Answer 5

Both Adafruit and Spark fun sell an assembled device exactly for this purpose: The Power Switch Tail exists in several variants, fully assembled or as kit. The kit's assembly instruction (PDF) include schematics.

Answer 6

Use a Telldus Tellstick!

It has many applications and supports sensors as well.

Code samples in many languages: https://github.com/telldus/telldus

A router which has an HTTP API to control the TellStick if you dont want to have it directly connected to the PI: http://www.dovado.com/index.php?option=com_content&view=article&id=13&Itemid=20

You can also buy a TellStick Net device and send API requests to Telldus Live from the PI (internet access needed).

Answer 7

X-10 serial interfaces exist. That would have the advantage of controlling AC switches that aren't right there.