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Yet Another Arduino 110v Power Controller

Yet Another Arduino 110v Power Controller
This Instructable shows you how to build a four-gang outlet box in which each outlet is controlled via an Arduino (or any other TTL level signals).

It differs from the other relay boxes in that it uses no circuit boards and has very few parts (one chip and 4 relays).
 
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Step 1Assemble Materials/Review Plan

Assemble Materials/Review Plan
Tools Needed:
Needle Nose Pliers
Wire Cutters and strippers
Screw driver
Soldering Iron
Multimeter

Materials:
Deep metal 4 gang output box and cover
Wire clamps
Two 15Amp outlets
Four 5v 10Amp relays (such as Jameco’s 843155)
A ULN2803A (such as Jameco’s 34315)
A 5volt – 500ma Wall Wart (such as Jameco’s 164101)
A length of 5-conductor wire (I used Cat5 cable)
Household current rated wire with a male three-prong connector at one end.
Miscellaneous wire and solder
5 minute epoxy
Wire Nut

Theory of Operation:
The electricity flow to each outlet of a four-outlet household current box is controlled via TTL level signals (such as the output pins of an Arduino).  Five wires are connected from the Arduino to the outlet box, four wires being connected to four Arduino output pins and the fifth to the Arduino’s ground pin.  A separate 5 volt wall-wart is used to power the outlet box (the outlet box relay activation coils will consume nearly 500 milliamps and a separate wall wart is used here so as not to stress the Arduino power supply).  The TTL control lines are wired to the inputs of the ULN2803A which can handle the relay coil current needs and also contains diodes to safely manage the back EMF produced by the relay coils when switched off.
 
NOTE: for simplicity the schematic only shows a single outlet connection.  Repeat the wires for the other three relays and other outlets, using ULN2803A Pins 3 & 16, 5 & 14, and 7 & 12.
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12 comments
Apr 26, 2011. 9:20 PMTerryKing says:
Lots of information on Arduino power control here:

http://arduino-info.wikispaces.com/ArduinoPower

Regards, Terry King

terry@yourduino.com
Jan 5, 2012. 5:49 PMRich1953 says:
Nice write up, and a fun way to get into power control. Also could easily be expanded. If you want to bring the power supply requirements down the relay could be replaced with a Photo-Triac
This is a type of switch to control AC current with an LED.
A solid state relay would also work. but that would be for a more permanent instillation
Apr 30, 2011. 8:55 PMfluxor says:
Try using a tiny cell phone charger. I did in one of my projects. They are switching supplies and are quite small, but will output 5v anywhere from 500mA to 1A depending on the unit.
Jan 14, 2011. 5:23 PMVoltamps says:
An excellent and well documented instructable. How about adding the script for completeness. I have done lots of electronics projects but am new to the arduino so any help with programming would be really welcome.

Many thanks.
Nov 30, 2010. 3:41 PMCity Lights says:
I would suggest to anyone playing with circuits that switches house main voltage to install a ARC Fault breaker at the panel or somewhere before your custom monkey business! This Is Not the same as a Ground Fault which saves You from getting electrocuted. Most electrical fires are started by Arcing. A small arc over time will carbonized where the electrical bounding has been broken or poorly made. Once carbonized, heat increases and increased heat can lead to Fire. Arc Fault Circuit Interrupters Saves Lives from Fires! ..and property and insurance hassles :) so play it safe and Happy automating!
Nov 13, 2010. 2:04 PMw0rm5 says:
Very Nice instructable, can I program the code and add it directly to the arduino? So I can work without the computer?
May 19, 2010. 9:29 PMComputothought says:
nte2018 = uln2803. if you have some really old disk drives, sometimes they have them.

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Author:maewert
I'm an aerospace engineer by trade but am interested in astronomy, robotics, CNC machines, Arduinos, you name it.