Safe In-Wall AC to DC Transformers??

[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.

[petewill]

@ServiceXp Thanks! I wonder if I can steal one of those from an existing device. Any idea what those would be used on?

(OTP, OVP, SCP)

Also, is that Over Temp Protection, Over Voltage Protection and Short Circuit Protection??

These say they are certified and have temp, voltage and short circuit protection. Think it can be trusted?
http://www.ebay.com/itm/351418782712?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[sundberg84]

This post is deleted!

[Moshe Livne]

@petewill @ServiceXp here is the datasheet http://www.hlktech.net/product_detail.php?ProId=54

it seems to have SCP and OCP but the OTP part seems to be left to the elements. I don't see OVP. I understand nothing of this.... Again, these looks well made, none of the crude soldering and flimsy elements you can see in the other converters (including the ones you get from wall warts). However, it being fully enclosed hides most of the details.

[Didi]

@Moshe-Livne said:

@petewill @ServiceXp here is the datasheet http://www.hlktech.net/product_detail.php?ProId=54

I will give them a try and order some for testing in a flush box.

[Moshe Livne]

@Didi Shame you won't be able to get them for the 4th of July

[petewill]

@Didi said:

I will give them a try and order some for testing in a flush box.

Great! Let us know what you find. Thanks for doing this!

[RJ_Make]

@petewill said:

@ServiceXp Thanks! I wonder if I can steal one of those from an existing device. Any idea what those would be used on?

(OTP, OVP, SCP)

Also, is that Over Temp Protection, Over Voltage Protection and Short Circuit Protection??

These say they are certified and have temp, voltage and short circuit protection. Think it can be trusted?
http://www.ebay.com/itm/351418782712?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Yes that is correct, and I don't think the HLK-OM01 has OTP, so for me, it's out. You looking for a 1 off transformer, or do you have some projects in mind?

[petewill]

@ServiceXp I was thinking about replacing a wall switch. So far all my projects have been outside a wall and I want to make sure I don't do anything stupid with this one. So, one off for now but I may make more in the future.

[DrJeff]

I'm seriously thinking it skipping all of these and build a transformerless circuit directly to the board like a true in wall switch, Pete do you want to share this project. I've been playing with this for a little while but haven't had time to put it all together. I can point you to all the places but a board will need to be designed for the switch, that's almost where I'm at!

[sundberg84]

Just à thought... I have these cheap 1$ 240 to 5 v USB power adapters charging 5-6 different equipments every day. These was sent with the equipment as standard so why are they not be safe?

[tbowmo]

@sundberg84

Some of the aftermarket wallwarts on ebay are very flimsy builds.. Lot's of teardown videos around, describing the different problems with them (like isolation distances not being kept at correct sizes etc).

[Moshe Livne]

@tbowmo @petewill @didi @ServiceXp I think I found the perfect one!!!!
http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2155823_-1
http://www.mouser.com/ds/2/260/GS05U-USB-spec-33533.pdf

it is made by meanwell, so not flimsy. has all protections. 8$ at jameco and mouser and I am sure my meanwell supplier on aliexpress can get it for me at half price... it is a shame that they do not sell the inside separately but nothing is perfect.
the only problem might be breaking it apart. Meanwell really make sturdy enclosures.
let me know what you think...

[Moshe Livne]

@sundberg84 I am using these as well, but not enclosed in a box or in the wall. Big difference.... when enclosed, the temp builds up and all the warning signs are hidden so its too late when you see smoke coming out of the wall. If a wall-wart combust on the outside of the wall chances are nothing serious will happen. If it does that inside the wall, with wooden frame nearby its a bit of a worry.

[sundberg84]

@tbowmo @Moshe-Livne Thx - good points.
Might be a good idea not to use them at all then... since you are not always home and can detect the smoke before its to late.
Hope this HLK-PM01 can be any good use... i dont want to pay 30$ and use z-wave in all in wall switches if i can do it cool and safe with mysensors... then you can play around with motion, light at the same time in the wall socket

[Moshe Livne]

@sundberg84 everything is a trade off... you take calculated risks all the time, weather you know it or not. With good external ventilation and not being overloaded I think these are safe enough. The meanwell wall wart is probably far superior but I am not sure I want to replace all my zillion wall warts. especially since it only comes with US plug i think and remains to be seen how easy it is to open.

[sundberg84]

Well, at the moment im building a relay much like the one in petewills video.
I used one of these cheap EU plugs from ebay/China.

Unforntually i got profe of how things can go if you do it wrong (and also proved my point above wrong). I removed the tiny cables to 240v and replaced it with thicker and longer cables... just in case. I must have used to much solder and got to close to another solder because when i powered it up - the plug lit ut like a blue firework for half a second before my main fuse couldnt take it anymore.

Well i was at a safe distance, and this is nothing to be proud of... but as a warning and "be safe"...
Even if this error for surtain was a man-made error I dont think i will be the last to try cheap wall wart plugs - so if we can find a satisfying "easy-to-use" converted that will be fine.

[petewill]

@DrJeff said:

I'm seriously thinking it skipping all of these and build a transformerless circuit directly to the board like a true in wall switch, Pete do you want to share this project. I've been playing with this for a little while but haven't had time to put it all together. I can point you to all the places but a board will need to be designed for the switch, that's almost where I'm at!

That sounds great! I just don't know if I have the experience to do all that. I'm fine with soldering and following wiring diagrams but that's pretty much the limit to my knowledge. I have a couple other projects on the list before this one but I would be happy to help in any way I can. Also, how easy would it be for other people to replicate the finished product? I think it would be really cool if it could be easy enough for people to build themselves.

[petewill]

@Moshe-Livne said:

@tbowmo @petewill @didi @ServiceXp I think I found the perfect one!!!!
http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2155823_-1
http://www.mouser.com/ds/2/260/GS05U-USB-spec-33533.pdf

it is made by meanwell, so not flimsy. has all protections. 8$ at jameco and mouser and I am sure my meanwell supplier on aliexpress can get it for me at half price... it is a shame that they do not sell the inside separately but nothing is perfect.
the only problem might be breaking it apart. Meanwell really make sturdy enclosures.
let me know what you think...

Those look good! The only problem I potentially see is that it's meant for external use. I would love to find a universal transformer that could be used for everything without having to modify it. Good find though!

[Moshe Livne]

@petewill Technically this is not true. The circuit inside the plug was made to be enclosed. Unlike other non brands I trust Meanwell. I have seen the insides of their LED transformers and a friend (that know much more then me) reviewed them as well for lights we built and they are excellent. Everything is always above spec. They are the reference when it comes to CC or CV transformers.

[RJ_Make]

@Moshe-Livne said:

@tbowmo @petewill @didi @ServiceXp I think I found the perfect one!!!!
http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2155823_-1
http://www.mouser.com/ds/2/260/GS05U-USB-spec-33533.pdf

it is made by meanwell, so not flimsy. has all protections. 8$ at jameco and mouser and I am sure my meanwell supplier on aliexpress can get it for me at half price... it is a shame that they do not sell the inside separately but nothing is perfect.
the only problem might be breaking it apart. Meanwell really make sturdy enclosures.
let me know what you think...

I think that one would be a good candidate for some testing.

[petewill]

@Moshe-Livne @ServiceXp Cool, thanks! By testing, what sort of testing could I do to know it's safe? Also, would I be able to open it up or would I need to keep in in the packaging?

My ultimate goal is to make a in wall switch similar to what I did with the "smart plug" (https://youtu.be/oNpMDN4QqD8). Do you see any other potential problems with putting those electronics in a wall? I want to make sure I don't do anything stupid before I attempt any of this...

I am planning on using relays like this: http://www.ebay.com/itm/261099571172?rmvSB=true

I would be powering lights so I shouldn't be anywhere near the 10A limit on these relays.

Thanks for all the help!

[Didi]

@petewill said:

@Moshe-Livne @ServiceXp Cool, thanks! By testing, what sort of testing could I do to know it's safe?

I have ordered 5 of them and i will test them at full 600 ma for 4 weeks in a flush box and protocoll data.I think if they don´t smoke we can use them on pcb

[RJ_Make]

@ServiceXp

Testing as in:

Ripple / Noise (if you don't have a scope just make sure the sensor does lock up on long run times at max load.)
Measure the heat it generates during full load (find something that can draw 1 amp).
Check to see if you can even fit it and the other components inside of a box that already has wire/switch run to it.

Personally, I would want to crack one of these open and see how it was designed. Making sure it's Ok, the specs look good on it, but you never know....

If the testing looks good, I would not have a problem using it (I would try and keep it in it's case if at all possible, or have one made that will house everything). I do think you are going to need a pretty deep box to fit it all.

We really need a MySensors Micro solution here, but then there is the liability.....

[RJ_Make]

@Didi Would you mind pushing one to 1 amp for a while., and then 1.5 if possible. Just want to make sure the OCP activates before it goes up in smoke..

[Moshe Livne]

@Didi Would you mind testing the meanwell ones as well? I would have but being on a small island at the end of the world is a problem sometimes. Don't mind buying a few for you for testing - I really would like to have both a reliable wall charger and a power supply I could use in a box without too much worry and the meanwell looks so promising....

[petewill]

@Moshe-Livne said:

I am sure my meanwell supplier on aliexpress can get it for me at half price...

Do you have a link for this? I just tried searching and I couldn't find these one ebay or aliexpress.

[rvendrame]

Adding my two cents, I have dissected two devices (one zwave from GE and one unbranded, non zwave) and both used a capacitor-resistor power supply.

Very dangerous, as it is "transformerless" --- In other hand, cheap and small footprint. By using X2 capacitors the risk is a bit lower. It is in my list for prototype/testing over next weeks.

[sundberg84]

@rvendrame So did i on a 433mhz relay sold quite common here... it looked as this capacitor-resistor power supply as well.

[petewill]

@rvendrame said:

Adding my two cents, I have dissected two devices (one zwave from GE and one unbranded, non zwave) and both used a capacitor-resistor power supply.

Very dangerous, as it is "transformerless" --- In other hand, cheap and small footprint. By using X2 capacitors the risk is a bit lower. It is in my list for prototype/testing over next weeks.

Interesting. Thanks for posting. I have very limited knowledge in this area so I'm learning a lot. I'm excited to get a good solution for this. It will be very useful for many things.

[Moshe Livne]

@rvendrame very interesting. The link mention only 100ma at most but I guess that they are using SSRs so don't face the problems we have with our relays. I wonder why there is no "off the shelf" unit like that. I would be a bit scared to construct something like that.

[Moshe Livne]

@ServiceXp @petewill @Didi here is another one! http://www.farnell.com/datasheets/606238.pdf

this one is reasonably smallish, has all the required protections. They are so well hidden....

[Didi]

@Moshe-Livne said:

@ServiceXp @petewill @Didi here is another one!

And pice is ok

Found one at ebay:
http://www.ebay.de/itm/5V-550mA-switching-power-supply-module-MYRRA-47122-PCB-mount-/301663807573?pt=LH_DefaultDomain_3&hash=item463c906855

[rvendrame]

@Moshe-Livne , I believe there is no off the shell as if you dig in the details, you will see that the impedance of the consuming circuit ( arduino + radio + relay in our case) direct influence the overall performance of the capacitor/resistor model.

Usually triacs consume less than relay (something between 10 and 50mA), and you can also control the bright of a light or speed of a motor, instead just turn them on or off.

The downside, you need a snubber circuit as well as a zero-cross detection circuit. The snubber is also recomended for relays, though.

So at the end you don't reduce the footprint or costs --- But triacs tend to last longer than relays, as no mechanical commutation occurs.

[DrJeff]

@rvendrame I'm right with you on all of this have been trying to do this for a couple months with no time right now. Actually it has been longer I was originally building all this for another system using XBees and then found it better to use esp8266 then said better yet use Mysensors so here we are! Transformer less is key at least I think so! Only problem no off the self builds.

[scalz]

Hi,

I found an application notes from enocean regarding power supplies design. I think it could be helpful, and good to remember, so I share the link.
http://www.enocean.com/fileadmin/redaktion/pdf/app_notes/AN101_POWER_SUPPLY_LAYOUT_2015.pdf

[rvendrame]

I'm currently studying this doc STEVAL-ILL004V1 AN2263 AppNote .pdf. I should prototype something over next week if family allows.

[scalz]

Hi. interesting link, I will read it when I will have time. It looks like u2008 or u2010 which are obsolete now (I have some in stock, cheap on aliexpress) but I didn't know your ref. thanks

[rvendrame]

@scalz, I'm trying to porting the capacitor-resistor power supply concept from that doc to our mySensor world. Specially for 1-wire dimmer, as described in chapter 3.1.

[scalz]

@rvendrame : I tried something similar once. I didn't remember exactly how all was connected but with triac, in one wire, even if I was not toggling anything, I had brown reset at start (maybe I could find my schem). With two wire, I had no problem but a little flickering (zero cross detection done by arduino). Maybe it was that which restarted. Next, I did another test with mosfet pwm, in one wire config again. This time, it started ok, and as I was increasing pwm it restarted for pwm = 170-200 (I don't remember exactly) .But I jumped onto another project I am finishing.
I will follow your results with interest as your link is interesting , and at my home it is one wire too.

[rvendrame]

@scalz, with the 1-wire circuit , the maximum you can reach is like 80% - 90 % of light bright, as you need to keep the triac/mosfet "off" for a short period, in order to recharge the PSU capacitor. Maybe that explained why it re-started on your test at PWM 170-200. (and would also confirm that it works 'as designed', good to know)

[ThinkPad]

I would be careful when stripping cheap USB-powersupplies and tucking them into a box in the wall. Read this page: http://www.lygte-info.dk/info/indexUSB UK.html and this page: http://www.lygte-info.dk/info/usbPowerSupplyTest UK.html to see how badly constructed some of these powersupplies are.

He also explains how he is testing those powersupplies: http://lygte-info.dk/info/usbPowerSupplyTestHow UK.html
Very informative i must say.

[Moshe Livne]

@ThinkPad Fascinating read.... If you read through the thread you will see that we actually go to the same conclusion. The meanwell charger should be good - they are respectable company and it has the 3 safeties we were looking for. It is not a very common charger - I have never seen it being sold before.

[petewill]

@ThinkPad Thanks for posting. It's good to see how the tests are performed. Unfortunately I don't have the equipment or skill to know how to test. Hopefully we will be able to find a safe one that we can all use.

@Moshe-Livne have you been able to find the meanwell chargers from anywhere besides jameco?

[Yveaux]

@petewill Mouser carries them, and also the european version (GS05E-USB). Please see here.

[Sparkman]

@ThinkPad Thanks for posting that. Great info there. Looks like you get what you pay for with the cheap power supplies.

Cheers
Al

[Didi]

@ThinkPad said:

I would be careful when stripping cheap USB-powersupplies and tucking them into a box in the wall.

Thanks for the information.The most powersupplies are horrible.
The engineers have developed them must go to jail.
Safety must be the major goal not the price.

[petewill]

@Yveaux Thanks. I was hoping there would be a cheaper way to get these. With shipping it's pretty pricey. Probably not as pricey as a fire though...

[Moshe Livne]

@petewill I have a supplier on ali that sells meanwell reasonably cheap. I used to buy all the power supplies for the LED lights I made from him. I will ask him for a quote. The downside is that he ships everything DHL.... still might be cheaper. where are you located?

[petewill]

@Moshe-Livne Ok, thanks! I live in Colorado, USA.

[jemish]

so finally....plz...tell me which power supply is the best to put inside in the wall?

I want required 5v for Relay, arduino mini, and radio.

[Moshe Livne]

@petewill My supplier is not selling these
apparently they are new
@jemish It is still a work in progress. @didi will do some tests and we are trying to get some more for testing.
Based on http://www.lygte-info.dk/info/indexUSB UK.html I would choose the apple one (http://lygte-info.dk/review/USBpower Apple USB power adapter UK.html)... But YMMV. I am not sure it has OTP

[Yveaux]

@jemish Be safe and buy something like: http://www.recom-international.com/pdf/Powerline-AC-DC/RAC03-SCR_277.pdf
Live on the edge (having a decent fire insurance) and tear down a USB charger or buy one of the few $$ versions from China .

[Moshe Livne]

I have asked the guy who made this excellent list to test the meanwell - hopefully he will oblige. I still haven't been able to find anything with OTP even remotely in this price bracket....

@petewill said:

@ThinkPad Thanks for posting. It's good to see how the tests are performed. Unfortunately I don't have the equipment or skill to know how to test. Hopefully we will be able to find a safe one that we can all use.

@Moshe-Livne have you been able to find the meanwell chargers from anywhere besides jameco?

[jemish]

@Yveaux this RECOM AC to DC converter will safe or not for put it to in the wall.

because I have to start live HOME Automation.

[Yveaux]

@jemish Its dimensions are especially chosen to fit in a standard round wall enclosure; its round and very flat, so it can be mounted behind a switch or some electronics inside a wall.
here you can find some use cases.

[jemish]

@Yveaux thank you for your reply....
You mean that I can put this RECOM inside the wall box...behind the switch board.

[Yveaux]

@jemish yes

[jemish]

@Yveaux where may I can buy it?

[Yveaux]

@jemish Depends on where you live. I bought mine from Conrad, and I know Farnell and Mouser also sell it.
Just google for some local suppliers.

[Moshe Livne]

@petewill @didi found a cheaper source:
http://www.tme.eu/en/details/gs05e-usb/mains-power-supplies/mean-well/
shipping to the US 9.90. still ridiculously expensive but not as bad as mouser

[scalz]

@Moshe Livne: interesting. I didn't know that tme has it. They have nice enclosure too, like those for wall ac adapter http://www.tme.eu/en/katalog/enclosures_100431/#id_category=100628&s_field=artykul&s_order=ASC&page=1
I live in EU. And for shipping I think they are good, regarding Rs, farnell, and mouser too. But not the same catalog unfortunately.

[Moshe Livne]

@scalz these are new i think and beibg propagated to shops. Every time I search i get more....

[Didi]

Powersupplies arrived

[Moshe Livne]

@Didi sharpening your knives and putting the plier in the fire?

[scalz]

aaaaaaah, you are lucky, I have not received mine yet!!!
I am thinking about something for OVP and OTP:

• at my job we use MCP9509 for OTP. As OTP is for output load (and not for input I think), it could be possible to use MCP9509 and P Mosfet to cut off the load if any temp problems occurs. I think it could be sufficient like this.
• for OVP, why not using a varistance at the input??? And then if a problems, your fuse in your electrical service box would blow.

I think this module has others protection.. so maybe it could do the job. I am not sure but like this I think it couldn't burn. It is just an idea as I am not expert. But can't wait to see how it is inside!!!

[rvendrame]

Mine arrived too. But I don't have equipment / knowledge to test it properly. So I will go for "real-life test". The wall boxes / wires here are fire-proof (and placed into brick walls), so the risk of real fire is reduced.

And I'm running my Arduino-dimmers for 6 months now, all powered by really cheap phone charges, so hopefully these modules will be a bit safer

[Moshe Livne]

@rvendrame would be interested to see how you wire everything together

[petewill]

@Moshe-Livne said:

@petewill @didi found a cheaper source:
http://www.tme.eu/en/details/gs05e-usb/mains-power-supplies/mean-well/
shipping to the US 9.90. still ridiculously expensive but not as bad as mouser

Cool, thanks!

@Didi can't wait to hear how they work! That was fast shipping!!

[Bertb]

Hi,
I am new here and decided to join this forum, because of this interesting discussion.
Some weeks back, I was looking for a cheap AC-DC converter and ran into the Hi-Link modules. The have very nice specs, but I discovered that there are no stamps to prove it.

I too plan to bring an offer to the gods of AC-DC, so I will build a module into a safe box and see what happens when I start annoying it.

I'd like to finish for now with a remark to rvendrame, if I may:
It is true that stone is very difficult to ignite, but fire and heat also melts the plastic coating of the elektric wires and this can lead to high currents that are just not high enough to blow the fuse in the mains fusebox and this can ultimately lead to fire elsewhere in your house.

Regards,
Bert

[rvendrame]

@Bertb, thanks for the advise!

[Atomfire]

I have also bought the Hi-Link modules, 10 arrived today, they seem very well built, but I have yet to try them.

[Qu3Uk]

I got some hi-link modules a while back on a "I might need these in the future" type deal.

I was wondering though how to protect the connections. I got some fuses+pcb holders to add extra protection however there is going to be at least 4 points which will be exposed.

Can I just cover the joints with hot glue to stop them from making contact with anything? Call me paranoid but I like to be extra safe.

[ThinkPad]

@Qu3Uk For covering solder connections you can use 'heatshrink'. Kind of 'plastic' tubes that you put around a wire, apply heat (keep a lighter/match underneath (not in the flame) for example) and it shrinks around the connection.

See also https://en.wikipedia.org/wiki/Heat-shrink_tubing

[Jan Gatzke]

@Qu3Uk You could protect the high voltage part of the circuit by mounting a plastic plate under the pcb using some spacers and screws. This way it would be impossible to touch the dangerous spots. I would not recommend hot glue because you never know how well it isolates. I don't think you will find electrical specs for hot glue.

[Qu3Uk]

@Jan-Gatzke Ah yeah that's probably a neater option as well I think. Sure I can find something suitable like that.
I have heatshrink but I just figured it wouldn't 100% cover the solder joints on the PCB.

[rvendrame]

@Qu3Uk , is a small plastic box a option? Maybe some 3D-printed, with some ventilation holes on two sides, as small as the PCB + components?

[Moshe Livne]

@Qu3Uk there is something called liquid tape. It's expensive.... Cool stuff though

[scalz]

@Moshe Livne. thank you for the trick. I didn't know this. it could be very useful sometimes.

[Moshe Livne]

@Qu3Uk Also, worse comes to worse, use PU construction adhesive. very messy but they are rated for electrical conductivity and fire. if you ever want to take this off, you are in big trouble....

[Qu3Uk]

@rvendrame Waiting on some boxes but I'm also wanting to protect the connections inside the box, figure it'll also be a little neater maybe.

[Moshe Livne]

@Didi Any initial results? curiosity is killing me....

[Didi]

@Moshe-Livne said:

@Didi Any initial results? curiosity is killing me....

Sorry Moshe no tests,i was in holidays with my kids

[Moshe Livne]

@Didi

[Bertb]

Last week I carried out an elektrical safety test on the HLK-PM01 to NEN 60101 (Dutch test for medical equipment) and it performed pretty well. I will try to post the file, after I removed some private information
Furthermore I am building a automated load tester that relates variable loads to output voltages and surface temperatures, based on an Arduino Nano.

[petewill]

@Bertb Great news! Looking forward to the results.

[Didi]

@Bertb said:

Last week I carried out an elektrical safety test on the HLK-PM01 to NEN 60101 (Dutch test for medical equipment) and it performed pretty well.

I can´t wait to see the results

[ThinkPad]

@Bertb Cool, always handy to have people like you on forums I'm also looking forward to the results!

[ThinkPad]

Maybe the "Samsung ETAOU10EBE" phone charger is also an idea to use. I have one for my phone, and it is very small.
I haven't opened it (i use it for my phone, dohhh), but the charger is small, so the PCB inside will be even smaller.

It is 5V @ 700mA with a microUSB wire. I got a second one from eBay, which was being sold as 'genuine'. And to be honest, i really don't see any difference with the one that came with my phone. It is working fine for more than a year.

[Bertb]

Well, here is the test file. I made it using test software named Ansur and a Fluke ESA640 tester in a Class II test setup.
The only problem is that some test results are in Dutch.

HLK-PM01 20150724 Fluke ESA620 IEC 60601-1 klasse 2.pdf

[hek]

For us none dutch talking people... Good or Bad? (Yes, I see the big PASSED text )

[Yveaux]

@hek I'm Dutch but I also have troubles interpreting the results...
But hey, I'm a software guy!

[Didi]

i guess fluke can set to eng,thanks @Bertb for the results,think you don´t make it at home

[Bertb]

Sorry for the language thing. I will try to get some tests in English in the future.
The tester used is designed for tests of medical equipment and this specific test proves that this specific HLK was safe. The problem is, however, that it does not prove anything with respect to the safety of other HLK's.

In the mean time, the same HLK is feeding a load of 730 mA. It's output voltage is 5.08 volts and the case temperature is Temp 46.81 Temp F: 116.26105.

@Didi. You are correct. I work in a hospital. I will try to setup the Fluke to English.

[Bertb]

Wait Mike, there is more ...
I sacrificed a device to the altar of success and opened it.
That was not very difficult. After scratching away some gum stuff the following was revealed.
I will try to remove the rest of the gum with acetone. I will also do some heat and burn tests.

This is quite funny to do

[Bertb]

And I found the AP8012 chip inside. It has the following features:
_1286955514_oj99d4.pdf

[Yveaux]

@Bertb Thanks Bert! Good digging!

[Moshe Livne]

@Bertb thanks! Good detective work! It seems the chip provide all the protections needed. That is very encouraging