Safe In-Wall AC to DC Transformers??
-
Did anyone look at the SwitchMote PSU over at LowerPowerLab? More info here. The kit is fairly expensive ($30) but I wonder how much it would be to source the components yourself since someone else has done all the design work.
@TD22057 I would say the cost of this PSU is dominated by the Recom converter onboard. Farnell charges E14,58 for single pieces (http://nl.farnell.com/recom-power/rac02-05sc/ac-dc-converter-2w-5v-reg/dp/1903060?searchRef=SearchLookAhead).
Rest of the components will be a few Euro's, and ofcourse the PCB (which contains a number of milled slots for isolation).
All together you will get fairly close to $30 when building it yourself. -
@Bertb Yes, it shouldn't be touched. It can be used with wall-mounted mains switches, though. Placed behind it.
-
@ceech said:
Yes, it shouldn't be touched
Nice! just label board !LIVE!
Not safe due to no fuse? Do share, making your own boards with solder mask?
-
So basically it is like any other consumer Zwave switch or X10 just box it up (3D printer on stand by) with 2 micro buttons with a rocker face and I want 10. :) But sorry I digressed from the OP in my excitement.
-
@ceech Yes I like the idea of course the board would be housed inside of a box, my idea is to incorporate the box with a daughter board with 2 push buttons on and off like Zwave switches use. Yes please send me, if you are worried I will use safely I was taught to work on all power 120v - 480v as if it is live so that you remain alive!
-
@ceech Yes I like the idea of course the board would be housed inside of a box, my idea is to incorporate the box with a daughter board with 2 push buttons on and off like Zwave switches use. Yes please send me, if you are worried I will use safely I was taught to work on all power 120v - 480v as if it is live so that you remain alive!
-
Another China iphone plug destroyed.
This has been working for 2-3 weeks without problems... the plug runs a 5v arduino and a normal 240-5v relay with button and led, standard sketch.
One day it just didnt started and i opened it up and saw a melted plastic cover and some burned component.
I have felt the relays a couple of times and noone has been really hot.
Im getting a bit shaky here... how far from disaster (big fire) is this?
-
BTW, the review of HLK PSU should be published in 'few days' according to the guy from http://lygte-info.dk . Can't wait for that!
-
@sundberg84 Yikes! That is exactly why I started this thread. I don't want to burn my house down...
@rvendrame Awesome! Can't wait either!
-
This is fantastic news!!
Would anyone be able to provide a parts list and wiring diagram based on the recommendations from the test site (pasted below)?
"A few notes for using it:
Electronic wears down faster when warm, especially capacitors, i.e. keep it as cool as possible for long lifetime.
I would place a fuse or fusible resistor before the converter, the fuse is not supposed to be replaceable, when it blows it is time to replace the converter.
A MOV accross the mains input would probably also be a good idea."
http://lygte-info.dk/review/Power Mains to 5V 0.6A Hi-Link HLK-PM01 UK.htmlOnce we have a that info I will update the first post so everyone reading this in the future doesn't have to read through 200+ posts to get to the conclusion. Thanks to everyone who helped with this!!!
-
The wiring is easy to describe.
Put a fuse in line between the "hot" mains AC input and the power supply module input (the "neutral" can go directly to the power supply). Put a MOV across the power supply input (on the PS side of the fuse).
For small spikes, the MOV would protect the PS by absorbing most of it. For longer surges, the MOV would cause the fuse to blow, probably sacrificing itself in the process.
Maybe others can help with component selection (for 120v and 240v mains). I see that in the case of Littelfuse, the fuse is rated by RMS AC voltage, so a 140v MOV would work for a nominal 120VAC mains). http://www.littelfuse.com/~/media/electronics_technical/application_notes/varistors/littelfuse_selecting_a_littelfuse_varistor_application_note.pdf
I don't know if RMS rating is standard, or if some are rated by their DC voltage conduction threshold, but one would want to be sure of that for the brand they are getting.
-
Some more thoughts from the guy who analyzed it:
"Hi Ricardo
It looks safe enough to me, except I want a fuse or fusible resistor before it. The purpose of the fuse is to blow when the module is worn down and maybe shorts. How fast it wears down will depend on temperature, at very high temperature it might be less than ½ year, at more moderate temperature it might be 10-20 years. The main culprit is the capacitors, their lifetime depends on temperature and quality of the capacitor.
Second risk for failure is large transients on the mains that may damage the module, again the fuse is there to prevent things getting out of hand if the module breaks down.The module can get hot if you pack it into the wall, especially if it is inside a lot of insulation. Doing a few test with a DMM and a temperature probe taped to the module inside the wall might be a good idea when running the module near full load.
I do not know the stuff used to fill with, but usual it will not easily catch fire." -
@rvendrame Thanks for getting this tested - that's a great result. The high temperatures he was testing at are for running at 1A of output but I thought that the 5V line is just for the Arduino and the radio which aren't going to use much current at all right?
-
@rvendrame Thanks for getting this tested - that's a great result. The high temperatures he was testing at are for running at 1A of output but I thought that the 5V line is just for the Arduino and the radio which aren't going to use much current at all right?
@TD22057 , exactly, under regular load (< 600ma), the unit should not get that hot. Once I get some time I will try the suggestion, by gluing a temp sensor on the unit and put it behind the wall switch.
Perhaps I will add the temp sensor permanently as a extra mySensor on the wall-relay, so I can capture the temp during the upcoming summer days. ;-)
-
Well, I must say, I am very happy with the result. Thanks for the testing.
So, I am already planning to use it in a number of devices. To avoid too high temperatures in confined boxes, it might be a good idea to glue a temperature fuse to it and wire it in series with the live mains wire. When the temperature rises above, lets say 75 degrees celsius, the fuse breaks down. -
It would also be good to link that temp sensor into the arduino. Then it could send out a "help my temp is to high" message before it shuts down. It should be possible to implement an overheated mode which would just blink a status LED on the front of the device and shuts everything else down until the temperature drops. Using the tricks of running a battery powered node should let the arduino power stay low enough for the PSU to cool down while still checking the temperature every few minutes and running the LED. The fuse would then be a fail-safe backup to the overheated mode.
-
Some more thoughts from the guy who analyzed it:
"Hi Ricardo
It looks safe enough to me, except I want a fuse or fusible resistor before it. The purpose of the fuse is to blow when the module is worn down and maybe shorts. How fast it wears down will depend on temperature, at very high temperature it might be less than ½ year, at more moderate temperature it might be 10-20 years. The main culprit is the capacitors, their lifetime depends on temperature and quality of the capacitor.
Second risk for failure is large transients on the mains that may damage the module, again the fuse is there to prevent things getting out of hand if the module breaks down.The module can get hot if you pack it into the wall, especially if it is inside a lot of insulation. Doing a few test with a DMM and a temperature probe taped to the module inside the wall might be a good idea when running the module near full load.
I do not know the stuff used to fill with, but usual it will not easily catch fire."@rvendrame said:
Some more thoughts from the guy who analyzed it:
"Hi Ricardo
*It looks safe enough to me, except I want a fuse or fusible resistor before it. The purpose of the fuse is to blow when the module is worn down and maybe shorts.
Would something like this be OK?
http://www.aliexpress.com/store/product/100pcs-LOT-PTC-Resettable-Fuses-TRF250-080-250V-0-08A-80MA-PPTC-Polymeric-PTC-PolySwitch-DIP/1653204_32267664975.html
