Introduction: Impowered Electrical Outlets

Picture of Impowered Electrical Outlets

This instructable will show you how to hack an off-the-shelf power adapter to make an internet enabled power adapter using the Electric Imp. This lets you turn on or off any mains powered device plugged into the adapter over the internet using a smartphone or web browser.

My garage "as-constructed" lighting is poor. You can use the available light for finding large objects like your car, but forget about that screw you just dropped. Never gonna happen. To fix the lighting problem I bought two 4 tube fluorescent shop lights to hang above my work area. Since the plug-point is in the ceiling roughly 12 feet high, I needed a way to remotely switch the lights on and off. I found a Stanley remote controlled power outlet at a local store and I was set, or so I thought. The first Stanley remote failed on day 1. The replacement unit failed after a couple of days. Third replacement unit failed a couple of months later. I never got around to taking it back to the store - I installed pull strings for the shop lights as an old-school temporary semi-remote solution.
What I needed was a WeMo or similar device. A perfect solution for my needs if maybe a little overkill. But, then it hit me. Most likely the failure point with the Stanley device is the RF circuit that controls the switching of the AC. If I replaced that circuit with an Electric Imp, I wouldn't need to mess with the AC circuit design which is already UL approved for safety, and would have a nicely made enclosure to boot.

I grabbed a Philips screwdriver and opened the Stanley unit up. The insides appeared to be PERFECT for an Electric Imp ( retrofit with minimal effort... or so I thought. My shop lights were headed into the internet cloud and accessible from anywhere with my Smartphone or web browser. Unfortunately the plan to just replace the RF circuit with an Electric Imp hit a major roadbump because the the DC power supply on the Stanley power strip cannot deliver enough current to power the Electric Imp. The Imp requires about 400mA on WiFi transmit, so the hack turned out to be more invasive than I had intended, involving an Imp, cellphone charger and relay board all shoehorned into the Stanley enclosure.

The final solution is perfect for those times when I forget to turn off the garage lights and have to walk back downstairs to check on them. No more - just check the status on the phone and turn them off if needed. Life just got easier!

Since the Holiday season is right around the corner,  this will allow you to control your light display from wherever you and your Smartphone happen to be, even if it is just from the couch to avoid the nightly trip into your snow filled yard.... just keep waterproofing in mind if you do this so that you don't unintentionally create an electrical hazard.

The Stanley unit I used is still available from various internet sites so if you want a basic WeMo'ish like device, with complete access to the source code and electronics that you can hack to perfection yourself, this Instructable will get you there. Think of this as Open WeMo'ish!

Step 1: How It Works

Picture of How It Works

The Electric Imp is the core of the system operation. When the button on the Web App is activated, an AJAX HTTP Request is made to a URL specific to your Imp. This request is sent to the Imp Agent in the Electric Imp cloud that is specifically associated with your Electric Imp.  The Agent code is a mini Web Server that parses the request and if valid, passes it on to your Imp firmware via the cloud. This behind the scenes communication between the server based Agent and the hardware based firmware was developed by the talented people over at Electric Imp.    

The Imp firmware receives the message from the cloud based Agent and sets the relay output accordingly. This allows you to turn the Stanley outlets off or on by pressing the button on your SmartPhone or web browser with minimal software and firmware development effort. Nice!

Step 2: The Stuff You'll Need

Picture of The Stuff You'll Need
There are many variations of remote controlled AC power switches. These are very popular during the December holiday season in the USA. Most likely, any of them can be hacked in a similar fashion. This is the parts and tool list for the Stanley unit I used.

  • Stanley Remote Powered Outlet. The unit I used is still available for about $16 from   I like the convenience of having 3 outlets
  • Electric Imp
  • Electric Imp carrier board
  • SainSmart 2-Channel Relay Board. Has opto-isolator inputs. I bought this board for another project. At that time (August 2013) it was under $5 delivered with Amazon Prime. The current price is $9
  • 1 x 4 Pin Molex connector. I bought mine from
  • 1 x 3 Pin Molex Connector.
  • 5 x Connector contacts for Molex KK Series connectors.
  • Thermistor - 10K (Optional - I still need to write the code for this)
  • iPhone USB Charger for powering the imp - Amazon has the best prices
  • USB Cable that will be mutilated to supply power to the Imp. If you get one with a small plug end (like the one that comes with the iPhone, you will be able to avoid the connector mutilation step!)
Tools and supplies

  • Philips screw driver for disassembling the Stanley unit. Needless to say your warranty is void as soon as you do this
  • Soldering Iron and solder- Radioshack has a variety
  • 24 or 26 or 28 Gauge hookup wire for connecting the electric imp I/O to the relay. Radioshack has different colors of 24 gauge available
  • Sharp utility knife
  • Small electrical tools (wire cutter, wire stripper etc)
  • Small drill bits (1/16") and drill for making the Imp Slot in the side of the Stanley unit. Alternately a Dremel tool with appropriate cutting bit.
  • Hot Glue Gun and Glue Sticks for mounting the Electric Imp and the Relay within the housing. I used the high-strength type..

Remember, as soon as you open the Stanley Remote AC Outlet switch, your warranty is void. Also, make sure you work with appropriate safety procedures for main powered devices. Unplug the Stanley unit before working on it. While it is unplugged, you can work on it safely without fear of accidentally shocking yourself.  If you attempt to work on the unit while it is plugged in, the live voltages (115VAC) inside the Stanley unit are enough to kill you. Never work on the internals of the Stanley unit when the cover is removed and the unit is plugged in. Be safe.

For tools use standard DIY safety procedures and always wear safety glasses.

Step 3: Disassembly and Modification

Picture of Disassembly and Modification

The Stanley unit is opened by removing the 5 screws on the back side using a small Philips screwdriver. One of the screws may be hidden underneath a sticker. Once all 5 screws are out, gently ease the two halves apart.

Remove the remote control PCB and dispose of it. We won't be using it again. This is where the Imp will be installed.

There are 2 large plastic bosses molded on the lower plastic housing that the original RF board was mounted to. These bosses can be cut off with a pair of side cutters and be smoothed down further with a dremel tool. The Imp and relay circuit boards will be glued to the base. Removing the bosses is needed so that the relay board will mount low enough to clear the top cover when the Stanley unit is reassembled.

Remove the main circuit board from the shell. Using a Dremel tool with a cut-off disk, carefully cut around the existing circuit so that you leave only the AC part of the circuit board as shown in the pictures. Cutting the PCB is necessary to provide clearance for the new relays that will switch the outlets on and off. You want to leave the main AC tracks that support the power outlets. 

To provide a slot for the electric imp card, a slot needs to be made in the side of the housing. Initially I had intended to use the Stanley unit built in regulator to power the imp. When this proved to be inadequate power, I had to relocate the slot to the opposite side of the lower housing. To make the slot, drill a number of 1/16" holes in roughly a straight line, and then use a small file to square up the slot.  Don't make your slot where these pictures show..... look at the final pictures in the last step to see where the slot should go!

Step 4: Electrical Detail and Assembly

Picture of Electrical Detail and Assembly

The original relay in the Stanley unit was equipped with a 250VAC/10A relay that required a 12V coil voltage to switch. Difficult to actuate from a 5V circuit so it was replaced with a dual relay module.

Please make sure the Stanley unit is not plugged in before you start work on it. 

The relay board I used has two 10A relays that will switch with a 5V coil voltage. In order to ensure a 15A rating of the hacked unit, I used the relays in parallel to provide a load rating of 20A. This provides a decent safety factor for a power adapter connected to a standard 15A breaker protected home wiring circuit. If you use a higher current relay, you could switch the power outlets individually. If the power strip is rated at 15A, then any of the outlets must be safe to operate to 15A. By wiring the relays specified for this instructable in parallel, you can ensure that any single outlet or all 3 outlets together can draw 15A safely. More load than this and the circuit breaker in your home wiring panel will trip to protect the circuit.

The power for the electronics is supplied by a iPhone USB charger. I had a spare that I could use. They are inexpensive and available on Amazon and ebay. It is cheaper to buy the charger which comes with a USB cable than to buy the components to build your own power supply. The iPhone form factor works well in the limited interior space of the Stanley unit. Use spade terminals to connect directly to the AC terminals of the charger. Use heatshrink to cover the exposed parts of the AC terminals to prevent accidental contact. The USB cable I found in my project box had a bulky molded connector. Using a sharp knife, the plastic moldings were removed. The red and black wires of the USB cable where replaced with 26 gauge wire to provide more mechanical robustness and then the connector was further protected using heatshrink as seen in the pictures. 

Originally, I had intended to switch the relays independently so that I could control at least 2 outlets independently. That is how the circuit was originally wired up. After investigating the current carrying capacity of the relays, I chose to parallel the relay outputs. The connection between the Imp and the Relay board has two Imp pins controlling each relay. In reality, you can just connect one Imp pin to both relay inputs. The firmware switches both pins together so either way is fine.

The AC Neutral and the AC Ground is already connected to the electrical outlet sockets. Leave everything connected the way it comes from the factory.  The only wire that needs to be modified is the AC Live wire (Black Wire). This wire needs to be t'd or branched so that you have a live wire entry to each relay as shown on the schematic. Protect the join with heatshrink. I used a small piece of 16AWG wire for this branching. 16AWG multistrand wire can typically carry 22Amps when used for short haul chassis wiring.

The relay outputs are soldered to the underside of the AC PCB as shown in the picture. When all the connections are made, squeeze everything into the housing as shown and hot-glue the relay and imp boards to the housing base.

Step 5: Imp Firmware,Agent Code and Blink-up

Picture of Imp Firmware,Agent Code and Blink-up

In order to get your imp to work, it needs to connect to your wireless network. Electric Imp provides a tool that does the configuration optically. The process is called BlinkUp and is detailed here

Once the BlinkUp is complete, your imp will appear on your IDE under New Devices. If you have not used an Electric Imp before, I suggest you first try the Hello World example on the Electric Imp site to get the hang of the Imp. There is also a great guide to the imp on instructables written by @beardedinventor:

The firmware for the imp is attached to this step as ImpoweredImp.nut
The code for the agent is attached as ImpoweredAgent.nut

Firmware and Agent code interaction
Your Agent has a URL specific to it. When an HTTP message is sent to this URL, your Agent code running in the Imp Cloud checks the validity of the request by comparing the incoming API Key (any key you make up - more bits make it harder to guess) with the API Key stored in memory of the Agent (API Key idea from If the Key's match, the message is checked to determine if a buttonPress event or Status request is being passed in the HTTP Request packet.

If the HTTP Request is for status, the Agent code returns the On/Off status of the AC outlets. The status is asynchronously updated by the Imp firmware when the output pins change state.

If a buttonPress event is passed in the HTTP Request, this event is passed to the Imp firmware over the electric imp secure communication channel between the Imp and the server based Agent. The Imp "receives" this event through the agent.on("buttonPressed", function( value ) function. Every time a button press event is received by the Imp, the output state of Pin1 and 7 is toggled which turns the relays On or Off depending on the previous state.  The status variable is sent back to the agent via the Agent-Imp communication channel and is received by the Agent in the device.on function.

Step 6: IPhone HTML/Javascript Code

Picture of IPhone HTML/Javascript Code

The client app is a bare bones HTML/Javascript app. A simple image is used as a button. When the image is pressed, the button animates to show WiFi packets emanating from the device.

Communicating with the Electric Imp is done by sending a message to the URL of the Agent which is specific to your particular Imp. In the HTML App, we create an XMLHttpRequest object and then post the button press event in a formatted JSON packet to the agent URL."POST", "" + new Date().getTime(), true);
xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xmlhttp.setRequestHeader("x-apikey", "Your API Key");
var impRequest = { "request": "buttonPressed", "button" :  };

To get status of the power outlets, the Agent is queried"POST", "" + new Date().getTime(), true);
xmlhttp.setRequestHeader("x-apikey", "Your API Key");
xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
var impRequest = { "request": "GetStatus" };
xmlhttp.send( JSON.stringify( impRequest ));

To make the HTML page appear as a native App on your iPhone, you need to load it from a web site, and then add it to your home screen. The process is described in my previous instructable here:

The iPhone files are attached to this step

Step 7: It Works!

Picture of It Works!
After all the building, configuring and maybe even a little bit of cursing, you should have a WeMo'ish device that you can control from your iPhone/Smartphone/Web Browser from anywhere you happen to be. There are many uses for an internet enabled outlet that makes your home that much smarter. 
  • Remote control of your in-house devices like lamps, hi-fi, TV etc. You can enhance the software and build multiple devices to allow you to control the lighting of your home to make people think that the house is occupied while you are away. You can turn your TV on and off to add to the illusion. You could enhance the firmware and smartphone software to program each device to run on a different on/off schedule to simulate the random nature of real people within your home to complete the illusion for security purposes when you are away.
  • You can add remote control for difficult to access power points.... my garage lights for example!
  • You can see the status of your outlets to answer the questions that always seem to come up after you are already many miles into a trip away from home like "honey did you turn the iron, hair hot stick, fish tank filter, pool filter, light timers" on / off depending on the nature of each device.
  • Add motion sensor to automatically turn things on/off when motion is detected.
  • Add a Thermistor or other temperature sensing device to monitor the room temperature. 
  • Figure out how to connect to so that you can, for example, email, FB Message, Tweet your outlet to turn on /off
  • Please comment below and I'll add your ideas to this list!

If you build one, please add to the comments and let me know of any additional features you added or alternative power outlet devices you hacked to achieve the same end. Also, if you figure out how to IFTTT this thing, I like to know how too!



ferke (author)2015-06-07

Wrong label after relay (AC Live).

eronand (author)2015-06-07

It should be cheaper use spark core instead electric imp.

eronand (author)2015-06-07

It should be cheaper use spark core instead electric imp.

eronand (author)2015-06-07

I see good opportunity connect this project to smartthing.

bitsandbots (author)2015-06-04

I bought several of the wireless powered outlets a while back, deciding they weren't right for the project I had in mind... but you've given me many ideas with this Instructable. Thanks much!!

You are welcome!

ArjenW (author)2014-10-25

Whith my first imp project i need a little help.

Can you tell me why i get the message: ERROR: the index 'x-apikey' does not exist

below my logging

2014-10-25 09:52:35 UTC+2[Device]imp.configure command is deprecated2014-10-25 09:54:54 UTC+2[Agent]url and api: 09:54:54 UTC+2[Status]Device Booting; 3.09% program storage used2014-10-25 09:54:54 UTC+2[Device]Impowered2014-10-25 09:54:54 UTC+2[Device]imp.configure command is deprecated2014-10-25 09:56:44 UTC+2[Agent]HTTP Request Headers: (table : 0x7fc0ccc58880)2014-10-25 09:56:44 UTC+2[Agent]HTTP Request Body: 2014-10-25 09:56:44 UTC+2[Agent]HTTP Request Method:GET2014-10-25 09:56:44 UTC+2[Agent]ERROR: the index 'x-apikey' does not exist2014-10-25 09:56:44 UTC+2[Agent]ERROR: at webServer:26
MidnightMaker (author)ArjenW2014-11-05

Hi, sorry I missed this message. Send me your email address via a PM and I will help you find the problem. All I can think of from the description is that you did not copy all the code properly into the agent.

ArjenW (author)MidnightMaker2014-11-09

After putting in the APIKEY and the IMP id in the right places, it all works fine.

Thanks for your help.

jeremydouglas14 (author)2014-09-29

I am working on this project and have a question.

I have finished the hardware section, successfully blinked the imp to my home wifi, inserted the code into the Agent and Device sections of Electric Imp's IDE page (and sucsessfully built and ran the software).

I am having problems getting the cellphone code/app to work. Is there any section in any of the code that I need to insert the url for my imp? Do I need any web hosting services or to publish the html code to get it to run on my iPhone? I have very limited code writing experience (only MatLAB in college) and am stuck. Thanks for any help!

Jeremy, you do need to modify the HTML code. Search for a line:

and then replace the YourURL text with the actual URL for your imp. This is typically a crytpic set of characters like c8fheu439

You find this in the Imp IDE near the top of the screen. There's a link called "Agent link" CLick ti to expose your unique agent URL.

The other change you need to make is to the API Key, This can be any text you want as long as the text in the Agent matches the text in the HTML file.

To get the code loaded on your iphone, you can load the HTML and manifest file from any web server. Once cached to the phone, you no longer need the external web server.

Hope that helps you move a step closer to completion!

Thanks for the help! When I make those changes to the coding and save the HTML file it appears to work correctly when I launch it on my desktop computer. However, it is not supplying power to the device I have plugged in.

I was looking over my hardware and the only thing I can think of is the single wire connection from the JD-VCC pin on the relay board to the Electric Imp breakout board. Where exactly did you make the connection on the Imp board? The circuit diagram at the top of page 9 looks like it is tied into the +5 Volts DC line from the USB charger but the picture in the middle of page 10 looks like it is connected to the battery pin of the board.

I followed the picture on page 10 and have the wire connected to the battery pin (I still have the bridge attached to the other 2 pins right next to it). Should I change this and solder the wire to the +5V DC wire going into the Vin connection on the Imp breakout board?

Once again thanks for your time!

Jeremy, look at the schematic at the start of step 4 and just follow that. DC+5V goes to VIN on the Imp which goes to JD-VCC. It is the common 5V line.

That did the trick. Thank you for the help!

jpietrzak (author)2014-09-07


Just curious, is it possible to control multiple imps from the same web address/page? I am trying to build something to control multiple devices nearby. This tutorial is one of the more simple ways I thought about going about this. Any input would be greatly appreciated! :)

MidnightMaker (author)jpietrzak2014-09-07

Yes it is. Each imp has a unique Agent URL by design. To address an imp you send a message to that unique URL. Your client side HTML page can incorporate a separate button for each imp for example. So you would load a single html page which addresses multiple imps. If you had 5 imps controlling 5 different outlets for example, you would have 5 on off buttons on your html page and each button would be associated with a specific imp URL.

valleyapps (author)2014-02-11

Was just wondering if you do not mind where do you place the 8.2K 1/4W 5% resistor.

MidnightMaker (author)valleyapps2014-02-11

Oops, that's a mistake in the parts list. I have updated the Instructable.

valleyapps (author)MidnightMaker2014-02-11

@midnight thanks mate, I looked at for like two hours trying to figure it out from the comments and Great projects, I am hoping I have the skills to pull it off, if I should have any questions is it ok to ask you sir?

MidnightMaker (author)valleyapps2014-02-11

No worries, I'll help where i can!

valleyapps (author)2014-02-11

Great Job, just bought all the ingrediants to give this one a try. I was wondering where do you apply the 8.2K 1/4W 5% resistor.


hobbyman (author)2014-01-14

Nice fabrication & design. Great project.

MidnightMaker (author)hobbyman2014-01-16

Thanks - I appreciate the comments

tamberg (author)2013-12-08

Hi, great tutorial. Triggering this with would require them to support custom Webhooks. Products like WeMo can afford to negotiate with them and build a custom adapter, but this seems not to be an option for DIY projects (though Mike Kuniavsky did it for his hardware startup Fortunately, Zapier, a competitor of IFTTT, does offer generic Webhooks ( and they support quite some Web apps as well ( Cheers, Thomas

MidnightMaker (author)tamberg2013-12-09

Thanks for the Zapier link. Now I've just got to find the time to try it!

mlseim (author)2013-11-17

I have to sort of laugh at these comments. This is Instructables, not Underwriter Laboratories. The Instructable imp light controller I made is thrown together with junk parts and indoor lamp extension cords. I don't think anybody here is posting projects that are ready for production. If someone has the knowledge and experience to build projects like MidnightMaker's Impowered Outlet, I would certainly expect them to use some common sense and wisdom in how they use the projects.

kyle brinkerhoff (author)mlseim2013-11-20

please tell these guys that here

csoldier83 (author)2013-11-12

Hahaha I'm not even considering attempting this, it's way out of my league, but this instructable is one of the clearest I've ever soon. Kudos to that man

dddddd (author)2013-11-10

This is an attractive build. Messy electrical work is usually a sign of failure down the road, and this build is neat and tidy.

One caution: you have entombed a number of active devices in an enclosed box, and there is no ventilation. The original wiring and connections are very likely to tolerate the increased temperature that will inevitably result, but the imp and the charger might not fare so well.

Non-code compliant (NEC or NFPA) electrical devices should be carefully evaluated before they are allowed to operate unattended in homes.

I'd perform an aggressive test, which you might have already done: Place the device in a warm, fireproof location, and plug in a number of reasonable loads, perhaps 5 amps apiece, and leave it there for 12 hours, testing the imp occasionally. Check the sockets and plugs in the sockets for hotness with your hand.

If the device catches fire, or the imp fails, you might consider labelling it as derated. Anything that can happen, such as forgetting that the device is not fully capable and using it inappropriately, will happen. You might also pull the cover after the test and check for signs of overheating.

MidnightMaker (author)dddddd2013-11-11

Thanks for your insights. I do have a thermistor connected to the ADC input of the Imp as part of the circuit. This could be used to automatically shut the unit down if temperature exceeds a certain limit - and then you can tweet this to your phone. I just have to get around to implementing the code - there are examples of temoperature monitoring and tweeting on

Your concerns are noted and this is a good test guideline for anyone building their own. Thanks!

dddddd (author)MidnightMaker2013-11-11

>thermistor connected to the ADC input of the Imp...


dddddd is absolutely correct. Electrical codes call for a certain amount of empty space in an enclosure to allow for heat dissipation. I would be very careful with this until it has been used monitored long enough to be sure it isn't going to overheat.

ac-dc (author)dddddd2013-11-10

I agree, BUT electrical outlets have a tendency to increase in resistance or arch as they age so passing an initial test unfortunately doesn't qualify it as safe, particularly when there is hot glue involved as a mounting method.

diy_bloke (author)2013-11-10

Indeed it is pure genius and I am impressed,
But i was wondering if it was overkill, or maybe I did not quite understand your problem. If it was just about having a remote control for a tube light, it seems a bit like an expensive solution (imp 30 usd, impee shield 20 usd). I am sure for that price you could have gotten a ready made unit that does not give up like yr stanley units Sure you would not be able to use yr phone or web browser to switch it, but who cares.

It is different of course if you want to switch something on and off from the other side of the world :-) But then the WeMo is already available at 50USD

zacker (author)diy_bloke2013-11-11

I was thinking "Just install a Light switch on the wall next to the door" but I do know what the OP means by "wanting to do it even if it was overkill" because I too am guilty of doing that same thing! lol
It is a very cool way to control lighting and it doesn't HAVE to be used for an every day light switch... for example, it seems a lot better to me than those "on at dusk off at dawn auto switches" you'd use while on vacation to make it appear someone And its also nice to use like if you come home later than expected and thought, "I wish I had left the front light on ALL DAY, just incase I came home in the dark, id be able to see!" lol good job!

MidnightMaker (author)diy_bloke2013-11-10

As I mentioned in the intro to the instructable, I wanted a WeMo even though I thought it was overkill for my needs.. But I had everything I needed already available so it cost me nothing to make. If you didn't have all the stuff available in your project drawer (or drawers in my case!) it would cost you about $66 in which case a WeMo would make more cost sense. But you can't learn about how things work without pulling them apart or by making new things. It is the act of "making" that heightens the understanding. Also, if you make it yourself you have 100% control over how the system works - you can program it for your exact needs.

diy_bloke (author)MidnightMaker2013-11-11

I fully agree and I am impressed

charlessenf-gm (author)2013-11-10

With all due respect, would it not have been simpler to either 1. replace the duplex outlet with an X-10 unit, or 2. simply run wire from the outlet(s) over to the stud wall and down to a convenient height and install an Old Work outlet box and wall switch? a 25' coil of 14/2, Old Work Box and switch would cost less than fifteen dollars retail. I think the X-10 would cost about twenty five dollars between the controlled outlet and control box (there are several options including a wireless control approach - all 'plug and Play.'

If you want to leave one side of a Duplex outlet 'always on' and the other side switched, you can break the tap on the hot side and run the switch to one outlet and leave the other 'hot' directly connected.

Granted, you'll have to crawl about in the attic and do a bit of Basic Electrical work and 'carpentry' to install a wall switch, but the result is 'standard' and provides the option to install an X-10 wall switch which provides both a manually-operated wall switch and one that can be remotely activated.

If you own your home, than an X10 outlet would work, but if you rent, you can't really go about installing new outlets or cutting holes in the walls. This instructable works great for people who can't modify their dwelling.

No worries my friend... I had a spare Imp in my toolbox..... and no X-10 hardware or ever any experience with X-10. I already had the Stanley unit so I just hacked solution with what I had handy. There are many ways to achieve the same end.... this was just my way.

Badge SA (author)2013-11-10

Looks like a bought one! Well done

Kasm279 (author)2013-11-10

Could you imitate the signals the remote control board gives off to switch the pre-existing relay instead of adding a new board?

MidnightMaker (author)Kasm2792013-11-10

That was my original goal as discussed in the instructable - just replace the existing RF board inside the unit with an Imp and use the existing relay. Ran into problems because the power they supply is insufficient to run the Imp. To fix the power problem I added the cell phone charger which is only 5V out - not high enough voltage for the original relay which requires 12V. If you can figure out their direct rectification circuit, and change the design to deliver at least 500mA, then you can use the existing relay.

VadimS (author)2013-11-07

Great job. Your comment on the 10A relay has me puzzled.
I build CSA/UL certified panels, now industrial and residential regulations differ slightly, But I'm vary confident in saying the original power controller violates them.
Probably a sample was provided for UL testing, then the Chinese company that built it cheeped out on components for the production run.

wa7jos (author)VadimS2013-11-10

Also, these relay contact ratings are for a NON-inductive load (like an incandescent lamp). You have to de-rate them for inductive loads like fluorescent lamps or motors.
You need to be careful to measure and monitor your load even for something as simple as Christmas lighting. You'll be surprised how quickly those light strings add up to a kilowatt (8-9 amps).
I have a remote switch I wanted to use for my dust collection in my shop. It was rated:
15A resistive, but then goes on to say
1/3HP motor (250W),
500W incandescent (4A, but a bigger surge current when the "cold" filaments are energized), and
400W TV (because that would be inductive too).
I opened it up and it had a nice big relay with 20A contacts. I decided part of the de-rating was due to the current carrying capacity of the circuit board traces. I beefed those up with some wire and have used it successfully with one caveat - DON'T turn it off while the motor is in the start cycle. The extra starting current generated an inductive kickback when I opened the relay. It arced so loud it would wake the dead! I opened it up and there was no damage. As others have commented, it is when the relay contacts BREAK that have the most impact on the relay rating.

MidnightMaker (author)wa7jos2013-11-10

Thanks wa7jos

iPhone chargers are notorious for being faked. Check out YouTube for "real vs fake charger" and you'll see that VadimS here is probably on to something :)

MidnightMaker (author)VadimS2013-11-07

I found something odd in the datasheet for the original relay. It has different ratings depending on who the approval agency was:
UL 15A @250VAC
CSA 15A @250VAC
TUV 10A @250VAC

I guess each agency tested a sample and rated it according to their test results. So technically, in UL regulated areas, which applies to me, it is ok. In Germany where TUV controls the regulation, it would not be ok. I updated the post accordingly.

VadimS (author)MidnightMaker2013-11-08

That would explain that.
Just a slight word of warning, two relays in parallel increases there current caring, but it does not increase how much current they can break. The two relays won't open up at exactly the same time (even if only a few micro second difference) and one will be breaking the full current, so running something that draws more then 10a will eat the contacts faster, but I wouldn't say it's a safety issue.

rgrimm1 (author)2013-11-10

I like your work, I just have a different/analog device I've been using for years...a pull-chain switch and a long string. Of course, you have to be there to turn on the light which defeats the remote purpose...which has it's uses for security reasons.

I have other analog hacks as well.

"Any sufficiently advanced technology is indistinguishable from Magic." What you do is Magic. :) Kudos for figuring out how to do it with a better set of reliable electronics.
Not knocking the idea down, I do things old-school.

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