Safe In-Wall AC to DC Transformers??

[petewill]

@TD22057 Thanks for posting! It's great to get more info on this. Maybe someone else can weigh in who has more experience but this is comforting "While it is not great, I would consider using it on my own projects..."

[TD22057]

One more note: There is also an HLK PM03 which outputs 3.3V.

[Soloam]

Hello, did any one attempted to make this project? what is the feedback? Is it safe? I was looking for something like this, but I must confess that this is a big step! I never liked using mobile chargers, I always asked my self if they are safe to use... If this is a step up to make my project safer, I would give it a go!

[sundberg84]

I did: https://www.openhardware.io/view/13/In-Wall-ACDC-Pcb-for-MySensors
But still there are many questions - I dont know what happens if it fails for example and if the components meant to protect it is good enough.
I have some temp test but not been able to test it with overload and stuff like that.

Also a relay board with HLK PM01: http://forum.mysensors.org/topic/1540/110v-230v-ac-to-mysensors-pcb-board

[Pierre P]

Do you want some tips to make "safe" crash tests ? Like putting it in a closed electrical box and switch on and off an old vacuum with no electronic ? Or make a shortcut make the relay ko... Because you cannot test that if you don't have a good electrical installation at home...

[sundberg84]

@Pierre-P That i have tested (the vacuum test) and the fuses blew... i was thinking about a long but not high overload.

[alexsh1]

@punter9 said:

http://lygte-info.dk/review/Power Mains to 5V 0.6A Hi-Link HLK-PM01 UK.html

Please see this:

https://skippy.org.uk/5v-acdc-converter-switch-power-supply-module-3w-700ma-industrial-voltage-regulators/

1. It does not comply with the UK standards (I live in the UK)
2. It is dangerous and not safe.

[sundberg84]

Yes, if you read the threads about this - we have alof of those examples... thats why we are using the HLK-PM01 and are having this discussion. That link is not about the HLK-PM01 @punter9

Edit: that guy you linked to tested the HLK as well:

"While it is not great, I would consider using it on my own projects, however it would need filtering on the mains side if I was going to use it in a project I was going to place on the market (read as sell), as under my control I can keep an eye on it causing unwanted interference with other equipment, this is why we have the limits set in the standards."

and if you read our conclusions from this thread its the same.

[alexsh1]

@sundberg84 Did you see it? The guy is using fuse (Farnell part number 2464451) and varistor (Farnell part number 1004390) for HLK-PM01. It is 0.8A fuse

[sundberg84]

@alexsh1 Yea i saw it - and the text say: "I got this generic even cheaper board" - its not a HLK he is testing...

[alexsh1]

@sundberg84 Yes it is - sorry I am now talking about this link https://skippy.org.uk/quick-look-at-the-hlk-pm01/

This is the fuse he is using
http://uk.farnell.com/bussmann-by-eaton/c310fc-800-r-tr1/fuse-pcb-0-8a-250vac-fast-act/dp/2464451?selectedCategoryId=&exaMfpn=true&categoryId=&searchRef=SearchLookAhead

This is a fast act 250V 0.8A fuse

[sundberg84]

@alexsh1 - Yea, ok - we have discussed that test above in this thread as well.
As far as I know the HLK is the best so far.

We also have another test where we have got different advice about fuses, (normal/temp) and varistor (see above).
Im accually using a 0,2A fuse for 240V. Read through this post if you are interested - its a great discussion.

[alexsh1]

@sundberg84 I have gone almost through the whole topic. Excellent discussion!

I think the difference is that you are using the slow blow fuse 0.2A and he is using fast acting 0.8A one. I really wonder which one would be more safe. I know slow blow fuses are used with inductive load (like motors), but not sure about this application.

I know it has been mentioned here as well, but did you make any provision for a thermal SEFUSE (say, 73C) or do you think it would be too much?

[m26872]

Let's hope skippy.org.uk also will recommend some good EMC line filters for the HLK-PM01 soon.

[m26872]

And about that cheap converter test. Since is an open type one with high res pictures from seller - too bad he didn't test an arbitrary other where the failed "visual inspection" could have passed simply by a look at the pictures. (I even think those blue caps could be small ceramic safety ones).

Btw, found a version of EN 60335 here.

[alexsh1]

@m26872 said:

Btw, found a version of EN 60335 [here].

I've used this link

[m26872]

@alexsh1 Thanks, it was better in every sense.

[sundberg84]

@alexsh1 said:

I think the difference is that you are using the slow blow fuse 0.2A and he is using fast acting 0.8A one. I really wonder which one would be more safe. I know slow blow fuses are used with inductive load (like motors), but not sure about this application.

I know it has been mentioned here as well, but did you make any provision for a thermal SEFUSE (say, 73C) or do you think it would be too much?

Its a good a releveant question... im not sure about slow or fast, but when i read the slow blow can tolerate high levels of voltage for a short period and a fast (or quick) blow fuse is a fuse that bursts instantly when high power voltage is passed through it.

How i see it, we have the protection against high quick power voltages allready in the Varistor? (Im not educated in this - this is my brain/logic trying to add everything up). Allthough what i read is what you are saying - slow blow are often used in motors and fast blow on home appliaces.

In my PCB I use a 73dgr therma fuse as well, im using the exact same circut that petewill has in its first post in this thread.

[alexsh1]

@sundberg84

The varistor is against high voltage transients and surges. The fuse is for overcurrent.

I have just ordered 0.8A fast blow fuses - they will be installed on my boards.

[sundberg84]

@alexsh1 - yes offcourse, you are right - mixed that up.
I have some 0.5 fast blow - sounds like thats a better idea than slow blow @petewill.