Safe In-Wall AC to DC Transformers??
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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.
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@rvendrame So did i on a 433mhz relay sold quite common here... it looked as this capacitor-resistor power supply as well.
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@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.
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@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.
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@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....
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@Moshe-Livne said:
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
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@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.
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@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.
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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
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I'm currently studying this doc STEVAL-ILL004V1 AN2263 AppNote .pdf. I should prototype something over next week if family allows.
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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
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@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.
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@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.
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@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)
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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.
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@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.
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@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?
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@ThinkPad Thanks for posting that. Great info there. Looks like you get what you pay for with the cheap power supplies.
Cheers
Al
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@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.
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@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...
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@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?
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@Moshe-Livne Ok, thanks! I live in Colorado, USA.
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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.
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@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
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@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 .
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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?
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@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.
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@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.
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@Yveaux thank you for your reply....
You mean that I can put this RECOM inside the wall box...behind the switch board.
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@jemish yes
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@Yveaux where may I can buy it?
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@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.
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@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
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@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.
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@scalz these are new i think and beibg propagated to shops. Every time I search i get more....
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Powersupplies arrived
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@Didi sharpening your knives and putting the plier in the fire?
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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!!!
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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
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@rvendrame would be interested to see how you wire everything together
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@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 mouserCool, thanks!
@Didi can't wait to hear how they work! That was fast shipping!!
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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
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@Bertb, thanks for the advise!
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I have also bought the Hi-Link modules, 10 arrived today, they seem very well built, but I have yet to try them.
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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.
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@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.
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@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.
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@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.
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@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?
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@Qu3Uk there is something called liquid tape. It's expensive.... Cool stuff though
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@Moshe Livne. thank you for the trick. I didn't know this. it could be very useful sometimes.
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@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....
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@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.
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@Didi Any initial results? curiosity is killing me....
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@Moshe-Livne said:
@Didi Any initial results? curiosity is killing me....
Sorry Moshe no tests,i was in holidays with my kids
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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.
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@Bertb Great news! Looking forward to the results.
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@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
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@Bertb Cool, always handy to have people like you on forums
I'm also looking forward to the results!
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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.
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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.
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For us none dutch talking people... Good or Bad? (Yes, I see the big PASSED text
)
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@hek I'm Dutch but I also have troubles interpreting the results...
But hey, I'm a software guy!
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i guess fluke can set to eng,thanks @Bertb for the results,think you don´t make it at home
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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.
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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
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And I found the AP8012 chip inside. It has the following features:
_1286955514_oj99d4.pdf
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@Bertb Thanks Bert! Good digging!
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@Bertb thanks! Good detective work! It seems the chip provide all the protections needed. That is very encouraging
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Thank you very much. I agree with you ap8012 seems to be a good chip. As we can see, it is difficult to make it smaller if we want all securities...and for the price including shipping I think they will sell lot of these things!
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@Bertb it is hard to see from the photos, are the capacitors rated for 105c?
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@Moshe. Yes they are. I did not yet dug into that, but is that good news?
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Observe the air gaps.
I also tried to incinerate the gum stuff that is inside the module with a cigaret lighter.
After a couple of seconds it starts to glow, then, after some 10 seconds, the material starts to burn. But this stops within some 20 seconds ofter removal of the lighter.
I made a film, but it is too large to upload.I am not an expert on AC-DC converters, but I am quite impressed by the layout of the design.
The only thing that worries me is that I do not see how the OVP is created. On the other hand, this can be easily solved by adding a fuse and a ovp zener in the primary circuit.
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@Bertb yes,although to be expected. Did you see the comparison mentioned a bit earlier in this thread? That is the first thing he checked
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In the datasheet we can see it is implemented in the chip (in the block diagram) and how it works is explained at page 7. If VCC not well built, the chip would not work well I think.
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I do not totally agree with this. When I take a look at the example circuit and read the ovp text, I can only conclude that the output is protected, because the circuit seizes to work when VCC rises to high. Whatever happens to the input circuit, I don't know. Therefore I prefer a fuse and and a varistor.
Have a look at the tutorial link text
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@Bertb thank you for your testing!!! Although I don't know much about hardware I am gathering by the posts here that it is mostly good news!
So, now for the big question... If I were to add an external fuse like pictured here does everyone agree this is safe to put in a wall?
And, a follow up question if the answer is yes. Are there any basic tests we can do at home to verify the performance should be the same as what was tested here?
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@Bertb, thanks a lot. I guess you mention to put a varistor/fuse right at output of this device, for example a 7K 14V varistor in parallel, and a 500mA fuse in series?
And what about the fire burn test --- Perhaps is there a method to measure it (and compare to some standard?).
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I agree with you about varistor. it is a good idea.
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I did not finish the automated power tester, but I put an HLK with a DS18B20 temp sensor in a closed flush box(is that the English word for the box in the wall, used for domestic wiring?).
A simple resistor acts as a load and draws a 800 mA from the power supply. That is 33% more than the max continuous value. Voltage across the leads is 4.96. That is 5.08 without load. Not too bad. At 600 mA (100% load) the voltage is also 5.00.
The Dallas says that the surface temperature at the HLK is 48.19 c ( F: 118.74).
Also do not forget to mount adequate capacitors to reduce ripple.@petewill and @rvendrame ... Every country has directives regarding flammability. I cannot say which one is valid. I have seen some testing in the past. They put a burner under the device under test and waited to see what happened after removal of the source. In general (without any warranty whatsoever) when there are no flames or when they extinguish autonomic is good. If there is no hot material dripping from the DUT, that is also good. The test I carried out is described above. No dripping en self extinguishing. So I am satisfied.
Sorry, I cannot be more specific. I do not have the knowledge.@rvendrame: yes the fuse in series in the mains live wire en the varistor in parallel with the primary side of the HLK.
With respect to the varistor ... see the sheet below:
Take a value that is well above the normal AC tension of your mains power, but below the max input voltage of the HLK. so in Netherlands 250 volts will do.
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Now for the million dollar question ... would I mount a HLK in a flush box?
Well ... when equipped with varistor and fuse and with the load on the safe side ...
Yes, I would.
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@Bertb, thanks again. I got a bit confused, do you mean put the varistor + fuse into the PSU input (AC Mains)? I was more thinking in over voltage protection on output. So a low-volt varistor together with a fuse/ptc, both on the 5V output.
My concern is having something wrong into the PSU-PWM control, and somehow the AC mains leaking to the low-volt side, cause arduino+friends burn/flaming. But I'm a hobbyist, so maybe I'm guessing wrong here.
Maybe to be on safest side --- varistor + fuse/ptc on both AC mains and 5V rails?
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My initial safety is always toward the biggest danger ... mains in this case.
For the secondary part a simple semiconductor fuse and a zener (transzorb) will do.
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@Bertb that is actually a very good surface temp for overload from what I saw in the other tests. Very promising.
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At 535 mA, the temperature stabilizes at 39.81c /F 103.66
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From what I researched at internet, the most important safety measure is the isolation part. Most countries have similar standards. From the pictures above I see the PCB tracks from high and low voltage are clearly separated by at least 0.5cm , which I think is also a requirement in EU.
Maybe if we figure out a way to provide something between 7.5Kv and 10Kv into the its AC input for some seconds/minutes, and see what happens. This is the worst-case scenario --- A lightning event into the AC line during a electrical storm.
Despite it may (and will) burn inside completely, any high voltage should never be present at output, as well as no significant flame that may propagate fire should occur.
This of course requires costly and sofisticated lab equipment.
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The specs of the unit states that it resilient to high voltages. I tested it with 250 VDC across input and output.
As stated before in this threat, the specs are ok, it only lacks the stamps.
From what I have seen so far, the module is good for me.From the specs:
4.Safety Characteristics：
4.1Products designed to meet UL, CE safety certification requirements.
4.2Safety and electromagnetic compatibility
Designed with the input of 0.5A UL certified insurance;
PCB board using double-sided copper clad plate production, material for the 94-V0 fire rating level;
Safety standards: Compliance with UL1012, EN60950, UL60950
Insulation voltage: I / P-O / P: 2500VAC
Insulation resistance :I / PO / P> 100M Ohms / 500VDC 25 ℃ 70% RH
Conduction and radiation :comply with EN55011, EN55022 (CISPR22)
Electrostatic discharge :IEC / EN 61000-4-2 level 4 8kV / 15kV
RF radiation Immunity: IEC / EN 61000-4-3 See Application Note
4.3 Temperature safety design
At room temperature,the capacitors of this power , the inner surface of the main converter maximum temperature does not exceed 90 ℃;
Shell maximum surface temperature does not exceed 60 ℃
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Overall that looks like a pretty good AC/DC trans. The isolation boundary looks massive.
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@rvendrame @Bertb this guy detail his methods here http://lygte-info.dk/info/usbPowerSupplyTestHow UK.html
he has some kind of gadget that produce 2500v to 5000v.
Anyway, I am convinced that this is safe (or at least MUCH safer then what people here have been using). If one of the electrical wizards can detail the circuit with extra fuses, diodes and varistor (what is that???) I think it can help us all.
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@Moshe Livne, yes I think I saw that website. The list of equipment there is surely respectable, at least. I just wrote to the info@ there, asking if perhaps he would like to test one of this HLK PSU. I can send one or two of my lot, lets see if we get some reply.
The varistor is a device widely used for protection. It is connected in parallel with the AC mains. It will short the circuit in case the voltage exceeds its pre-determined value. The ideia is to use it burn an internal fuse, or trigger the house circuit breaker in case of over voltage. A 20K-250V varistor will short the circuit if voltage is above 250V, and it supports voltages up to 20KV without produce any flame.
Using a varistor in conjunction with a PTC fuse (a fuse that automatically resets after some time) creates a very good protection for over voltage, with small cost and footprint.
I do agree with @Bertb and @ServiceXp , this HLK PSU looks good and safe for what we intend to use. Surely it is better than a phone charger. But as in any DIY, each one of us must know where to step on, assuming the involved risks.
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@Bertb I live in the Netherlands just like you. If you're interested i can make some thermal images of the disassembled HLK unit if you send it to me. I expect my FLIR One (Android) to arrive probably next week.
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Just to be sure everybody understands the schematic, hereunder a schematic.
I am not a fan of blowing mains fuses ...
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@ThinkPad I am not sure it is still safe to operate.
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@Bertb The idea was to put it on my desk (with a mains cord soldered to it) running a resistor load, and then shoot some thermal pics of it
. I wasn't planning to touch the unit with my bare hands while it is powered hahaha
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@ThinkPad Well its your desk, so its fine with me.
Is there a way to get your address without shouting it from the rooftops?
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Don't suppose anyone could tell me what components (values) need to be purchased for 230v (UK)? I have bought 10 of these and wish to make them as safe as I can.
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@Bertb Have sent you a chat, see the chat balloon top right corner.
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@Atomfire I will come back to that tomorrow.
