Picture of BLU-BOARD, control your home with blue tooth!
Big thanks to the fine people at Hack-A-Day for sharing this with the world!
if you'd like to donate to the project:
This project has been in the works for along time, three months if I reckon Correctly, but anyways, this device will allow you to control devices in your home, whether it be your homes thermostat or your lights it all can now be done over blue tooth with ease. so lets begin.

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Step 1: Step 1: sourcing parts

Picture of Step 1: sourcing parts
you will need the following parts :

bareduino kit : $8.95
2 channel relay : $5.85
bluetooth module : $8.52
random header pins and sockets~$2.00
small piece of pcb~$2.00
programmer (optional) $9.00
enclosure (optional) $19.51
a led ~10 cents

Step 2: Step 2: producing main board

Picture of Step 2: producing main board
visualisation graphic.png
first we must produce the pcb for this device, in this instructable im not going to go over how to etch a pcb, if you dont know, just google it, anyways i designed the pcb in inkscape and it is available for download here in a zip file.
EDIT: peter__s created a gcode file as well if you wish to mill the board. thanks peter!

Step 3: Populate the pcb

Picture of populate the pcb
solder up your components as the image shows, this should be relatively self explanatory at this point, just make sure that the chip has its notch pointing to the left and that the led has its long leg going to the a0 pin on the chip. 

Step 4: Relay controller modifications

Picture of relay controller modifications
this next step is going to require you to use a header socket to replace the control pins on the relay module, this will require some de-soldering which can be tricky if youve never done it before . basically it should look like this when your done 

Step 5: Header construction

Picture of header construction
on the main board we have to use some extra long header pins to create a connection to the relay module, to do this cut a segment of header pins that is 4 pins long and push the little plastic piece to the end of the pins like shown in the photos and then push it through the board and solder it in place like so.
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bogon6 months ago

hi..can i use bluetooth from my android phone for send data 1 or 2 to activate the relay??

kyle brinkerhoff (author)  bogon6 months ago

yep but you'll need a bluetooth serial terminal application

hey i want to use this on 220v AC supply.. so how to manage the supply?

selp1 year ago
I've done the same ! but instead using one bluetooth module per board, i use a main board with one bluetooth receiver and a 433Mhz emitter. Child boards have only one 433Mhz receiver ! It's cheaper if you plan to make multiple modules ! and you've only one bluetooth receiver to connect to !
Raphango selp1 year ago

Whoa! Great idea man!


kyle brinkerhoff (author)  selp1 year ago

good idea

SPLatManOz1 year ago
Congratulations on an interesting design.

Be aware, however, that it violates important safety rules, and is potentially dangerous. Cheap relay modules typically are not safe for mains use, unless the whole board is safely isolated. The relays themselves may meet relevant UL/CE rules, but the PCB layouts are frequently in violation. See article here:

In this design the power comes from a wall wart or similar, plugging into a regular jack. That jack is potentially hot, if the inadequate insulation in the relay module breaks down. The power lead, being low voltage, is not insulated to mains standards.

A case should absolutely not be listed as optional.

Will you die? Most probably not. You will hopefully not even get a shock. But don't let your children play near it. If it electrocutes a neighbor you will not have a leg to stand on in court.
kyle brinkerhoff (author)  SPLatManOz1 year ago
measured the module, its safe, and yes the case is listed as optional because its 20 bucks to make, however no-were do I state its safe to use without the case! its implied that you use a substitution. If you do use it without a case your a fool and you probably dont have the skill set to make this in the first place.
measured the module?
kyle brinkerhoff (author)  SPLatManOz1 year ago
pcb traces
I agree with the OP, this is a really cool design. Having said that, measuring resistance of the PCB traces isn't telling you anything other than point A connects to point B, and so on.

OP brings up a very good point. If for some reason your relay(s) were to fail and the control circuit were to become hot with 110-120v AC, you may very well get a nasty shock (even start a fire) from the control board power adapter. Not to mention that controlling mains voltage all but commands the use of insulated wiring through-and-through, not bare screw-down terminal blocks. There's a reason all UL-listed appliances have insulation on every possible point of contact along an electrical cord.

$20 is a very small price to pay when safeguarding yourself and others who may use a homemade creation from potential electrocution in the event of catastrophic failure. "Implying" the use of any required safety feature is downright dangerous for anyone who may attempt to replicate such a project. Simply because someone might not think to use a case does not mean that said person is a "fool" who knows just enough to get themselves in trouble, but not enough to stay out of it. Such an approach can lead to people getting hurt.


This kind of application is really fun to work with if the proper precautions are taken. Best of luck working on the software side of this!
kyle brinkerhoff (author)  Patman271 year ago
then were do you suggest i find a ul rated relay module
Kyle, you probably can't buy a module. What you can do is buy suitable relays, such as Hong Fa JZC33F, that has 4kV coil to contacts breakdown (not 1.5kV like the Songle SRD in the module you used - AFAIK UL mandate 3.75kV). Unlike the Songle it also has pinouts that will easily allow 6.4mm between contact traces and coil traces on a PCB. Then you make you own PCB, ensuring at least 6.4mm between contact side and coil side traces. Use a ULN2803 or discrete transistors to drive the relay.

When you put it in a box, terminate the mains wires to the board and bring the cord(s) out through properly strain relieved glands. Keep the mains wiring physically segregated from all low voltage wiring. There should be barriers such that if a mains wire comes loose it cannot move and touch anything on the extra low voltage side - it's called two layers of defense, and helps people stay alive.

The relay module you used looks like one of those that have an opto-isolator coil drive circuit. That provides no safety, it is simply a noise abatement strategy. It is possible, with inductive mains loads, for enough noise to couple back through the relay from contacts back to the coil circuit, to upset a microcontroller. The opto-isolator reduces that risk.

Here's an idea for you: Build a mains power supply straight onto your own PCB. That way you eliminate the connection for the wall wart, and no human can ever touch any part of the circuit. Suddenly the need for isolation has gone away. The control signal comes in wirelessly.
kyle brinkerhoff (author)  SPLatManOz1 year ago
this is the correct rely?
Kyle, that looks like the one. We use thousands of those in our boards.
kyle brinkerhoff (author)  SPLatManOz1 year ago
no biggie, Im not an engineer so i only design things to work, not necessarily to be safe as well.
Not an engineer yet.   :)
BTW, Kyle, sorry if I stomped on you a bit hard before. After a career of doing the right thing I get a bit sensitive about transgressions. Maybe a bit more so because we (SPLat Controls) sometimes get hit in the marketplace by products, mainly from you-know-where, that don't do the right thing. With modest volumes, and using proper quality parts and design rules, we get beaten up on price. And of course, "they" fail to point out that their products could be unsafe to use.
Stupid question but what kind of knife is that in the background?
kyle brinkerhoff (author)  MattBothell1 year ago
gerber paraframe. and i freakin love it
fr0sty01 year ago

Very cool! How does the case fit together, does it snap or is it glued? Looks great, Thx for sharing!
kyle brinkerhoff (author)  fr0sty01 year ago
glued, but I'm considering a snap together system
Cool, so I guess you plan on not easily taking them apart afterwards? :)
Snap in would perfect it!
kyle brinkerhoff (author)  fr0sty01 year ago
with the glue method, the front panel is just pressure fitted to hold it in place, to do this I engineered the board in such a manner to cause it to bow the bottom piece of plastic ever so slightly to create a reasonable amount of pressure to hold it in place
Troels1 year ago
Where did you get the Bluetooth module from, and what is its name?? :D
kyle brinkerhoff (author)  Troels1 year ago
prasenjit1 year ago
need much money for that !!!!
shead35051 year ago
Well done Kyle! nice project. Good luck with Kickstarter.
kyle brinkerhoff (author)  shead35051 year ago
litris1 year ago
Very nice!

App for iPhone?
Please ;-)

kyle brinkerhoff (author)  litris1 year ago
sorry, need a mac first....
kyle brinkerhoff (author)  Stefniamoo1 year ago
money :(
Way to stick with it and nice work on the project !
Looks great !
Build_it_ Bob
kyle brinkerhoff (author)  Build_it_Bob1 year ago
electracks1 year ago

I can offer this enclosure for about 5$ plus shipping if you want. Just contact me at
kyle brinkerhoff (author)  electracks1 year ago
kyle brinkerhoff (author) 1 year ago
Please comment! the more input the better it can become!
Very nice.

One thing that I always look for in an article like this is a schematic. Often I'm not looking to recreate a project exactly but to gain inspiration or insight and am more interested in how something works than how to make it.

In this case it would be pretty simple to reverse engineer, but it would still be a nice addition to complete this article.

Also nice to have would be links to the parts used. In particular, the relay control board.
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