Safe In-Wall AC to DC Transformers??

[petewill]

Does anyone know of any 120V AC to 5V DC transformers that are safe to put in a wall electrical box? I have been using old cell phone chargers for most of my projects but I was recently pondering putting something right in the wall. Since shipping can take so long I thought I'd ask now before I even start on the project.

I did some searching and couldn't find anything so I thought I'd ask the experts here.

Thanks in advance!

EDIT 9/7/2016
Watch out for Fakes! Read more here: https://forum.mysensors.org/topic/1607/safe-in-wall-ac-to-dc-transformers/355
If in doubt you can get them directly from the vendor here: http://www.hlktech.net/product.php?CateId=10

EDIT 12/28/2015
After MUCH discussion on this here are the findings of this thread (as of now):

Here is the diagram for how things should be wired:

These are the parts I ordered. I haven't tested any of these parts yet as this project has been put on the back burner for now :(. I am in the USA so this is spec'd for 120 VAC. If you're using 240 you will need to change the size of the Varistor but everything else should be fine for 240.

Also, see these posts for more discussion/ideas if interested:
http://forum.mysensors.org/topic/1540/110v-230v-ac-to-mysensors-pcb-board
http://forum.mysensors.org/topic/2488/in-wall-pcb

Varistor for 120VAC - http://www.ebay.com/itm/321024816822?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

73°C Thermal Fuse - http://www.ebay.com/itm/221560426284?_trksid=p2057872.m2749.l2649&var=520415979885&ssPageName=STRK%3AMEBIDX%3AIT

250V 300mA Slow Blow Fuse - http://www.ebay.com/itm/111433875797?_trksid=p2057872.m2749.l2649&var=410420838583&ssPageName=STRK%3AMEBIDX%3AIT

HLK-PM01 - http://www.ebay.com/itm/351418782712?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Pete

[Didi]

@petewill said:

Does anyone know of any 120V AC to 5V DC transformers that are safe to put in a wall electrical box?

here you go
http://www.recom-international.com/pdf/Powerline-AC-DC/RAC03-SCR_277.pdf

http://www.tracopower.com/products/tiw.pdf

[Moshe Livne]

@petewill got these http://www.aliexpress.com/item/Free-Shippingn-2pcs-lot-HLK-PM01-AC-DC-220V-to-5V-mini-power-supply-module-intelligent/32296988259.html in the mail today. not as sexy as the ones @Didi lists but maybe cheaper? Haven't tried them yet.

[scalz]

Hi,
I have ordered same as @Moshe. I think those @Didi listed are larger and expensive. It is not very easy to find something small and cheap, or it needs to make your own.

[Moshe Livne]

@scalz I actually ordered the same as you :relaxed:
they look very well made. I am not equipped to test any of the parameters but i am sure that for me they will do.

[scalz]

@Moshe Livne : yep! it is the smallest and cheapest I have found. What could be great would be to find cheap and little core transformer to make custom step down.

[sundberg84]

As long as they dont catch fire and deliver 5v im happy! :fearful:

[Moshe Livne]

@scalz How do you connect these to the mains? direct soldering and heatshrink over?

[Didi]

@sundberg84 said:

As long as they dont catch fire and deliver 5v im happy! :fearful:

That´s the problem i see with the cheap ones

[Moshe Livne]

@Didi These are huge... they are 5x5cm. Do you have any idea of their pricing?

[Didi]

@Moshe-Livne

About 20-25 euro

[Moshe Livne]

@Didi ouch!

[Didi]

@Moshe-Livne said:

@Didi ouch!

Yes,but they have over temperature protection :wink:

[Moshe Livne]

@Didi it is cheaper to buy better fire and life insurance :wink:

[Didi]

@Moshe-Livne said:

@Didi it is cheaper to buy better fire and life insurance :wink:

That´s a good point :joy:

[scalz]

@Moshe Livne: it is ordered, I have not them yet. I hope it will be good quality.I don't know.
I agree with you for fire and co. But I think in commercial products they don't use big things.
As we can see on some picture here : http://www.aliexpress.com/store/product/Free-Shipping-Livolo-Luxury-White-Crystal-Glass-Switch-Panel-EU-Standard-VL-C701-11-110-250V/500715_512886492.html
Sure it is maybe not top quality, but I think in fibaro or other it's near the same thing. but I am not sure as I have none. And of course they have enclosure (maybe flame retardant).
Maybe I am not enough paranoid...or you can for example put an onboard temperature sensor for additional security.
But of course, ac is very dangerous, you must know what you do if you don't want to die. You have to take all securities like you said.

[petewill]

Thanks for the quick replies! I am torn. The ones @Didi posted look great but they are large and expensive. The ones @Moshe-Livne and @scalz ordered look appealing because of cost and size but I don't want to sacrifice safety for cost. It looks like they have temperature protection but I don't know enough about electronics to test for safety. Hmm...

[BulldogLowell]

@petewill

I wonder if you could open one of these and solder to the USB power leads...

[petewill]

@BulldogLowell Yeah I was thinking about that too. I'm really trying to keep costs down though. When I hit the $25 price point it's almost as much as a standard z-wave switch when all the other parts and time are included.

[RJ_Make]

My only recommendation; (if you are going to put this in side a utility box, in the wall) might want to find a solution that has the 3 standard safety features. (OTP, OVP, SCP)

These work well, but you need to follow the data-sheet for noise and ripple control.