Safe In-Wall AC to DC Transformers??

[hek]

Ok, removed the ebay link from the buying guide. If someone finds an alternative ebay seller with genuine modules, let me know.

[dbemowsk]

Sorry, I didn't mean to imply that I bought them from that link. Never the less, it sounds like those are not genuine.

[matz]

Hi Guys,

What a huge topic :)

Has anyone tested this 3,2 $ module ? Do you think it is safe to put it in the wall socket ?

AC-DC Isolated AC 110V / 220V To DC 5V 600mA Constant Voltage Switch Power Supply Converter Module

In the comments on guy disassembled it :

Regards

Matz

[korttoma]

@matz why not use the HLK-PM01 that is known to be safe?

http://www.hlktech.net/product_detail.php?ProId=54

[matz]

Hi

I understood that the HLK-PM01 can not be directly used out of the box, and that we need to solder it to a pcb with Varistor etc. but i may be wrong

I dont have the skills to do that for something potentially dangerous. I need something that can be used out of the box and connect it directly to a wemos mini d1

[Nca78]

@matz said in Safe In-Wall AC to DC Transformers??:

Hi

I understood that the HLK-PM01 can not be directly used out of the box, and that we need to solder it to a pcb with Varistor etc. but i may be wrong

I dont have the skills to do that for something potentially dangerous. I need something that can be used out of the box and connect it directly to a wemos mini d1

But from the pictures, it doesn't look like this is safer than an HLK... much more like the opposite.

They didn't even bother to make slots to increase creepage, while high voltage and low voltage sides are clearly way too close. You can compare with layout on the HLK here, there's way more distance between the too sides of the board, but still they added a wide slot under the optocoupler (on the side, next to R6) to increase creepage.
http://lygte-info.dk/pic/USB PS/P01 Hi-Link HLK-PM01/DSC_1454a.jpg

There's also no filling in the enclosure for extra isolation, to even the heat generated and to protect components from environmental pollution. It should be ok for dust because opening is small but not at all for humidity...

If you look at the product description of the exact same power supply (without the box) on AliExpress you can see they advise much more extra components than for the HLK: input fuse and at the output: RC filter, extra ceramic capacitor for high frequency noise, TVS diode and Y2 safety capacitor.
https://www.aliexpress.com/store/product/1PCS-SANMIN-AC220V-to-DC3-3V-600MA-3W-Power-supply-Isolated-switching-power-supply-module-220V/923896_32799372973.html

If you don't trust an HLK with extra safety (fuse + MOV) in your wall you shouldn't trust that thing. It doesn't seem to have much consideration for high/low voltage sides isolation and it's just been put in a plastic box like it is a complete and safe power supply, while the safety components advised by the original maker were not added...

[matz]

@nca78

Thanks a lot for this complete answer. I understand that i should use HLK but put in on a PCB and add varistor and fuse like described in the edit of the first post. The problem is that I really don't know a lot about eletronic. For arduino things in 5v or 3,3v I have no problem to try to do myself, in order to learn, but for 220v i prefer to use a finished product... Is there exist somewhere a finished product with the HLK and all necessary pieces, ready to wire to the 220 v and to the arduino/nodemcu ?

Regards

Matz

[sundberg84]

@matz I have made a breakout board. But using this and the pre-defined components you are on the right track. It's all easy to solder components (temp fuse can be a little tricky) . I don't have much time to source and solder assembled projects but have a look and you might get some ideas.

https://www.openhardware.io/view/504/HLK-PM01-breakout-board

[matz]

@sundberg84

Thanks a lot it is very useful and i'm sure i can do it myself with tour board already designed.

Juste one question : what are the sizes of the bard in all 3 dimensions ? I need to be sure it will fit in the wall where i need to put it before ordering the components. I could not find these info on the page you sent me.

[sundberg84]

@matz hmm, traveling now so can't measure but 50 long I'm sure. It's probably 35-40mm wide.

[matz]

@sundberg84
Quite small, so.

In a link above i've seen a review of the HLK from one guy who seems to know about electronics.

He recommends using the VIGORTRONIX VTX-214-005-105 AC/DC PCB Mount Power Supply . He said "for only a few quid more you win a switch mode PSU that stands a chance of not requiring external components to pass Class B!"

Anyone here has tested the Vigortronix ? Is it better than HLK ?

[dbemowsk]

@matz Never tried the Vigortronix, but I tried some from a company called Recom that were pretty good. Quite a bit higher in price though too.

[matz]

@dbemowsk
Ok thanks. I will try to build the sundberg84 board but i will try also to find a case built with a 3D printer as i prefer not to let all this stuff unprotected in case someone else than me in the futur open the wall socket

[dbemowsk]

@matz Now that I have had my 3D printer for a year, I don't know why I didn't get one sooner. FOr these very reasons. If I need a case for something, I cad it out and make it.

[matz]

@dbemowsk
I'm planning to buy one, i'm sure there are plenty usage of it (sorry for my bad english i'm french :))

Concerning the PSU, one question : we could just disasemble an iphone charger, the small one is 5cm x 1,5cm x 3 cm, and reuse it in the wall. IMHO it is more safe than build ourselves a PSU. Has anybody tried this ?

[dbemowsk]

@matz Why disassemble it other than to solder on some external power wires. Leave the original protection in place and you shouldn't have to worry about shorting anything out.

[matz]

@dbemowsk
I'm afraid it won't fit in the wall socket because of the metal stem, so it would be better to solder the power wires to it :

[Nca78]

@matz said in Safe In-Wall AC to DC Transformers??:

(sorry for my bad english i'm french :))

Ce n'est pas une excuse valable :P

@matz said in Safe In-Wall AC to DC Transformers??:

@dbemowsk
I'm afraid it won't fit in the wall socket because of the metal stem, so it would be better to solder the power wires to it :

It doesn't look like an official charger, or even a branded one ? Then you would meet the same safety problems than the cheap power supplies. In that case have a look at http://lygte-info.dk/ to check if you can find a charger that's on the "safer side" of things.

[sundberg84]

@matz the problem with phoneadapters are all the fake and truly unsafe ones. Just Google phone charger teardown. If you are sure you are buying a genuine one it's most likely quite expensive. Safety vs money is one of the key aspects in this thread and offcourse you can probably buy smaller and safer ones but you are going to pay for it.

[arp5z5]

Hi guys (and gals?) new member here, and probably an absolute novice compared to most of you; however, I have been following this thread for quite some time. I recently acquired the components listed out by @petewill (thank you for the inspiration to try the project), and I have constructed the circuit in tune to the schematic also generously provided by @petewill. The only difference in my set up is that I have gone with a WeMos D1 mini instead of the arduino/radio combo solely due to having one laying around. The WeMos to relay connection works (as in flicks on/off the LED on the relay) in tune with the automation software I am using when the WeMos is being powered by micro USB. However, when attempting to power the circuit via a 120V outlet, I seem to keep blowing the 250V 300mA Slow Blow Fuse. In short, the LED on the WeMos briefly emits light, and then shuts off. When troubleshooting the circuit with a multimeter, I find that no current is flowing through the Slow Blow Fuse (therefore blown). I was wondering if anyone might have some ideas as to why this is happening despite the fuse being rated with the proper current and voltage ratings. I assume that there is a short occurring somewhere in the circuit; however, due to my novice knowledge, I have no idea why. I would greatly appreciate any and all pointers/criticism! Thank you. https://imgur.com/0Iy0UwY https://imgur.com/a/ZuSlb