BLU-BOARD, Control Your Home With Blue Tooth!




hi i enjoy making ludicrisly over the top and complex devices.... Being an ameture engineer, I r...

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

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

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

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

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

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.

Step 6: Finish Populating the Board

now add the last two header connections to the board like so, and plug your new main board into the modified relay module.

Step 7: Upload Firmware

this step requires the arduino ide and the included firmware to make this thing operate, i designed this to work with the cp10102 uart tool for programming so you may need to make a special adapter to use a different programmer, but its fairly simple. when the board has its firmware the led should blink once when it turns on to let you know its alive and running.

Step 8: Plug It In!

now you can install the bluetooth module by simply plugging it in as shown in the photo, after which you can power it up and use a bluetooth dongle with your computer to send it commands. the board should be listed as hc-06 when you scan for the device and you can use the arduino ide to send it commands, to control it send a 1 or a 2 to control the first relay and 3 or 4 to control the second relay.

Step 9: The Case

this step is entirely optional but adds a nice finished product touch to it. to make it easy i had the case manufactured by ponoko and you can order one here
lso i included the original svg file if you happen to be lucky and already have access to a laser cutter 

Step 10: Final Thoughts

it was a long time coming to getting this far to the release of this to the public but i just want to let you know i went through 5 different iterations of the main board to get it all working right, but in the end it was totally worth it 

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    72 Discussions

    kyle brinkerhoffjestrada483

    Reply 3 years ago

    sorry, you will have to reverse engineer from the pcb :P its been a while since i made this and this instructable is all that survives of the files


    5 years ago on Introduction

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

    1 reply

    5 years ago on Step 8

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


    5 years ago on Introduction

    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 !

    2 replies

    5 years ago on Introduction

    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.

    11 replies

    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.

    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, 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.