Hi all,

**UPDATE April 17 2016 **
The latest version of this board is available HERE.

After spending a few months on this forum and a few prototypes later, I decided I wanted to build a small but cheap PCB which could be placed in either the wall behind the light switch, or above the lamp.

Besides the boards I've seen on this forum, I wanted these boards to contain a module to go from 230v AC to 5/3.3v DC in order to power an Arduino nano and the NRF module. I eventually ended up with a PCB which is about 4 by 4.5cm. So with all components attached I'm hoping to get in stuffed in a 5x5x3cm plastic printed case.

Modules which I've used to power the board:
[http://www.aliexpress.com/item/5-pcs-HLK-PM01-AC-DC-220V-to-5V-Step-Down-Power-Supply-Module-Intelligent-Household/32319202093.html?spm=2114.32010308.4.19.8oKfZg

UPDATE: 2015/09/18
As promised, I've got an update for this project. The board has been tested in the past week, and everything is working as expected. Compared to the previous board I've posted, I have updated the following:
• Solder pads of LE33CZ have been placed a little wider apart to avoid short circuit while soldering.
• Solder pads of the resettable fuse (Fuse2) has been placed closer together to better fit the fuses of the BOM.
• Moved the NRF24L01 connector a bit away from the solid state relay. Should make it easier to solder.
• Moved Fuse2 to another location on the board, away from the 230v circuit.

Some 3D pictures (Top and bottom):

Anyone who is interested can order the PCB HERE

Some documentation, complete list of required components and all gerber / DipTrace files (in case you would like to make some modifications) can be found here: MySensors board v3.2.3.zip.

For those who wanted to see some pictures of the board:

Small notice: These pictures are of a slightly older design. The newer design has a few minor changes like better component placement and a permanent fuse instead of this resettable fuse. But these pictures should at least give you an idea on how everything looks like, and shows how really small it actually is.
Also, I reinforced the traces of the 230v lines, which I absolutely recommend to do! (Although I do recommend to do it slightly more professional than I did on this prototype :))

As promised, I've got an update for this project. The board has been tested in the past week, and everything is working as expected. Compared to the previous board I've posted, I have updated the following:
• Solder pads of LE33CZ have been placed a little wider apart to avoid short circuit while soldering.
• Solder pads of the resettable fuse (Fuse2) has been placed closer together to better fit the fuses of the BOM.
• Moved the NRF24L01 connector a bit away from the solid state relay. Should make it easier to solder.
• Moved Fuse2 to another location on the board, away from the 230v circuit.

Some 3D pictures (Top and bottom):

Anyone who is interested can order the PCB HERE

Some documentation, and all gerber / DipTrace files (in case you would like to make some modifications) can be found here: MySensors board v3.2.3.zip.

Wow, this thread has been really active in the past few months! I'm sorry for my absence, but I kind of got dragged into other projects..

A new version of the board will be shared soon! Compared to the current board following changes have been made:

• A second solid state relay has been added. This 2nd relay is optional, so if only 1 device needs to be controlled just 1 relay needs to be installed and everything will still work fine.
• The board size has been increased just a little bit to fit this 2nd relay. Size is still 5x5cm only.
• Some components have been moved in order to make it easier to solder them (This was a bit tricky on version 3.2.3 because some components were really close to each other).
• Traces between the relays and the connectors are now 'open air'. So there is no mask on top of the traces. This way it is possible to reinforce the traces. By doing this it shouldn't be any problem to connect a 2A load to the board.
• A temperature cut-off has been added to the board.
• The varistor for the low voltage circuit has been removed because it's not really needed anymore with all the extra security measures on the high voltage side of the board.

Currently this board is still on it's way from China, but as soon as I've received this board I'll share all the documentation and everything else which is needed on this forum! This will probably happen in 3-5 weeks from now, so stay tuned!

Thanks for the detailed information about this project! I was/am looking for a similar solution to check whether doors are opened or closed.
Have you ever considered drilling a hole in the top of the door, and placing the entire node inside this drilled hole like the video below? Similar to this video?
That was something I planned to do, but your solution seems really nice as well in case drilling a hole in the door doesn't work out as expected.

As promised: In the attachment of this post you can find all required information to build this board.
The zip file includes all required Gerber files, bill of materials, as well as the Schematic and PCB design (drawn using DipTrace).

One remark: I've slightly adjusted the design to optimize the reception for the NRF24L01. The antenna of this chip is now placed slightly next to the custom PCB. Hopefully this will result in a better RF reception.
Size is approximately 47 by 42mm.

Download (Please be aware that this board is still untested at this moment, so please doublecheck things yourself before ordering!):
Check latest post for updated version.

Hi @shabba.
I assume you mean version 3.2.3 of the board?
Besides the silkscreen of the LE33 being the other way around, there are a few other things to keep in mind:

• The drill holes of the fuse/varistor on the 230v side might be a bit small. So it is advised to either make those holes a bit bigger, or to make the legs of the fuse/varistor a bit thinner using some sandpaper.
• Make sure to solder the components in the correct order (As mentioned in the Word document, which is part of the ZIP file of the opening post).

I'll update the first post of this topic in a few weeks, which includes the newer board version that fixes all the problems as stated above.

Any chance you will be creating a 'panelized' version of this board? With these small sizes 4 boards can be fitted on a 5 by 5cm board, while still keeping the same price. I'd be happy to order a few if that's available!

@Jan-Gatzke You are absolutely right. No idea on why I've never thought about that!
I have now redesigned the board to fit a relay as well. Size is still limited to 45 by 45mm, so it should be quite easy to place them behind a light switch.

I hope to receive my PCB boards next week, after which I'll add all components to the board and start testing it. If all goes well, I'll be submitting the new design with relay to dirtyPCBs to have those printed too.
Just a sneak peak of the new board:
Top:

Bottom:

In the following days I'll start designing a 3d-printable casing to fit the board.
As soon as I have confirmed that the board with relay is working fine, I'll submit the PCB design here together with the 3d printable casing. Due to slow shipping and limited spare time I expect this to happen in about 4 to 7 weeks.

I'm really happy to hear that these HLK power modules are considered to be safe. I've been using them for a few weeks already, but didn't have a clue what was inside (and whether they were ACTUALLY safe).

One question regarding the varistor and PTC fuses though:
Any reason (or specifications) why you chose those specific components? I've been looking for myself as well, but came up with slightly different components.

Fuse1 and 2: PTC Resettable Fuses 250V 1A TRF250-1000

Varistor1: [10D391K 10K391 390V varistor diameter 10mm AC 250V DC 320V]
(http://www.aliexpress.com/item/Varistor-10D391K-10D-391K-VDR-10K391-Metal-voltage-dependent-resistor-50pcs-bag/1912418587.html)

Varistor2: [5.5V Varistor original Varistor resistor]
(http://www.aliexpress.com/item/SMD-1206-5-5V-Varistor-original-Varistor-resistor-100pcs-lot/32243046238.html)

If anyone with a bit more experience could have some feedback on these components, that would be really really appreciated!!

@Soloam I'm actually not using 2 100nF capacitors, but 1 100nF and 100 uF capacitor. Exactly for the reason that scalz mentioned. I'm not saying these are the perfect values to use, but I came across similar values some time ago, and these give me a decent and stable voltage.

The width of my copper traces is 2mm for the entire high voltage circuit. I have used a trade width/thickness calculator, and it should be more than sufficient to power the HLK-PM01.
However, it is not sufficient for the traces between the relays and the connectors because it should be able to handle up to 2A (limiting factor of the solid state relays). That's why I have designed this board with open air traces between the relays and the connectors. That way it's possible to reinforce the traces with solder, after which it should be able to withstand 2 Amps.

And good luck with designing your version of the board! If there is a way to decrease the board size even further that would be great!

@jemish
It's on the middle of the board on the top side. 4 pins are present to use as switch inputs. 2 pins are ground, and then pin 4 and 7 are available as well.
By closing the connection between pin 4 and ground you will switch te status of relay 1. When closing the connection between ground and pin 7 you'll switch the status of relay 2.

@Samuel235
I assume you were referring to the 2 resistors at the high voltage circuit? These were actually used as placeholders for the temp cutoff and the slow blow fuse. As I didn't have these component in DipTrace I used resistors to replace them in the scheme. But I have updated the schematic to avoid any confusion!

As for the EAGLE software: Is does meet all the needed requirements, but I just find DipTrace to be way more user-friendly.

@Samuel235 At the moment I have one board (version 3.3.1, which is missing the temperature sensor) up and running for over a week. It's in a small closed box, and it has two lamps attached to it which are powered on every evening. So far everything seems to be ok. Temperature is still low inside this box after a few hours (couldn't perform any specific measurements yet, so that's why I added the temperature sensor in this one).

@Cliff-Karlsson I just soldered the thermal fuse really quick. But maybe some other kind of heatsink would be useful! So any suggestions are welcome for this.

@Samuel235 I have been using DipTrace to design all my PCBs, and I must admit that the schematic view in this software kit isn't the best.. I'll see what I can do to have the schematic quality improved! But all components which are on the schematic are on the PCB, so no components are missing on the board itself.

The latest version of this board is available here!
Because of the large number of request a second (optional) solid state relay has been added to the board. Enjoy!

@Sefi-Ninio
Yes, it will be perfectly possible to just install 1 relay on the board and it will still work fine.
More news in the next few days!

@jemish
Then your wait is almost over! I'm currently doing my latest tests on the board, and so far everything works perfectly. I'll try and see if I can post everything during next weekend.

Have you ever considered adding a weight/pressure sensor underneath the legs of your bed?
Lets say if the weight of your bed would be 100kg, that the arduino is configured set to toggle at 110kg?

Hi @shabba.
I assume you mean version 3.2.3 of the board?
Besides the silkscreen of the LE33 being the other way around, there are a few other things to keep in mind:

• The drill holes of the fuse/varistor on the 230v side might be a bit small. So it is advised to either make those holes a bit bigger, or to make the legs of the fuse/varistor a bit thinner using some sandpaper.
• Make sure to solder the components in the correct order (As mentioned in the Word document, which is part of the ZIP file of the opening post).

I'll update the first post of this topic in a few weeks, which includes the newer board version that fixes all the problems as stated above.

@jemish The boards were sent to me from China 5 days ago. I don't have a tracking number available, but usually it takes between 3 and 5 weeks before they reach me (Belgium). I already have all the necessary components, so within a week after I received the boards I'll provide this topic with an update.