Safe In-Wall AC to DC Transformers??
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Something went wrong with uploading the file, I think.
Herewith a new schematic with a suggested bill of material.
It is highly experimental still, but I ordered the components yesterday.I am specially interested in working with the PTC fuse.
I hope the proposed circuit works for you. Please keep the maximim continuous output power in mind. It is only 3 Watts (600 mA).
In some cases you might need to add C1's (rule of thump 1 per chip or chip VCC) and/or need to increase the value of C2. This depends on the fluctuations in the power demand.With the proposed values for C1 and C2, the ripple remained below 50 mV at 500 mA.
Also keep in mind that a remaining oscillation frequency residue appears in the output of some 60kHz.. If capacitors are not able to filter that out, a small coil might be needed.Well it is experimenting that makes this fun, isn't it?
@Bertb can now see the scheme! thanks. But can't see the BOM
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... it must be friday ...
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As you please ...
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@Moshe-Livne said:
@rvendrame Considering cost of postage and logistics involved it would probably be cheapest to just order two units from Ali to him? its 8$ including shipping if i remember correctly
Yes, it makes all sense. The only downside is that if we buy all at same time probably he will get all from the same lot, but in my opinion it by far doesn't invalidate the testing.
So, myself, @Bertb , @Didi = 3 PSUs, better than 2. I will share with you both the ship-to address ok? Thanks a lot!
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I'm really happy to hear that these HLK power modules are considered to be safe. I've been using them for a few weeks already, but didn't have a clue what was inside (and whether they were ACTUALLY safe).
One question regarding the varistor and PTC fuses though:
Any reason (or specifications) why you chose those specific components? I've been looking for myself as well, but came up with slightly different components.Fuse1 and 2: PTC Resettable Fuses 250V 1A TRF250-1000
Varistor1: [10D391K 10K391 390V varistor diameter 10mm AC 250V DC 320V]
(http://www.aliexpress.com/item/Varistor-10D391K-10D-391K-VDR-10K391-Metal-voltage-dependent-resistor-50pcs-bag/1912418587.html)Varistor2: [5.5V Varistor original Varistor resistor]
(http://www.aliexpress.com/item/SMD-1206-5-5V-Varistor-original-Varistor-resistor-100pcs-lot/32243046238.html)If anyone with a bit more experience could have some feedback on these components, that would be really really appreciated!!
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@Moshe-Livne said:
@rvendrame Considering cost of postage and logistics involved it would probably be cheapest to just order two units from Ali to him? its 8$ including shipping if i remember correctly
Yes, it makes all sense. The only downside is that if we buy all at same time probably he will get all from the same lot, but in my opinion it by far doesn't invalidate the testing.
So, myself, @Bertb , @Didi = 3 PSUs, better than 2. I will share with you both the ship-to address ok? Thanks a lot!
@rvendrame said:
@Moshe-Livne said:
@rvendrame Considering cost of postage and logistics involved it would probably be cheapest to just order two units from Ali to him? its 8$ including shipping if i remember correctly
Yes, it makes all sense. The only downside is that if we buy all at same time probably he will get all from the same lot, but in my opinion it by far doesn't invalidate the testing.
So, myself, @Bertb , @Didi = 3 PSUs, better than 2. I will share with you both the ship-to address ok? Thanks a lot!
:+1:
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I'm really happy to hear that these HLK power modules are considered to be safe. I've been using them for a few weeks already, but didn't have a clue what was inside (and whether they were ACTUALLY safe).
One question regarding the varistor and PTC fuses though:
Any reason (or specifications) why you chose those specific components? I've been looking for myself as well, but came up with slightly different components.Fuse1 and 2: PTC Resettable Fuses 250V 1A TRF250-1000
Varistor1: [10D391K 10K391 390V varistor diameter 10mm AC 250V DC 320V]
(http://www.aliexpress.com/item/Varistor-10D391K-10D-391K-VDR-10K391-Metal-voltage-dependent-resistor-50pcs-bag/1912418587.html)Varistor2: [5.5V Varistor original Varistor resistor]
(http://www.aliexpress.com/item/SMD-1206-5-5V-Varistor-original-Varistor-resistor-100pcs-lot/32243046238.html)If anyone with a bit more experience could have some feedback on these components, that would be really really appreciated!!
@aproxx I would say that the 50 mA fuse is too weak. The HLK draws between 0.1 and 0.2 Amp and can surge 10 Amp. So, I think the 1A version is good for both situations input and output. The varistor is only good for the output.
One thing to consider though. This is also chinese stuff ... is it really safe or are we introducing a new problem? :smile: -
@Bertb Aaah yes now I see. It does seem to draw much more peak current than I expected! Then I'll just use the same component as I'm using for Fuse 2.
What do you mean by "The varistor is only good for the output."? You're using one as input and one as output in your diagram as well or am I missing something?And yes, I know this is Chinese stuff again.. But single (chinese) components never failed on me (until now). :smiley:
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@Bertb Aaah yes now I see. It does seem to draw much more peak current than I expected! Then I'll just use the same component as I'm using for Fuse 2.
What do you mean by "The varistor is only good for the output."? You're using one as input and one as output in your diagram as well or am I missing something?And yes, I know this is Chinese stuff again.. But single (chinese) components never failed on me (until now). :smiley:
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@Bertb I see what is getting both of us confused.
Apparently something was wrong in the link of my previous post, resulting in the 2nd varistor not being listed. So now your comment about the varistor only being good for the output makes sense as well. :smiley:
I've fixed the link of my post above! -
@Bertb I see what is getting both of us confused.
Apparently something was wrong in the link of my previous post, resulting in the 2nd varistor not being listed. So now your comment about the varistor only being good for the output makes sense as well. :smiley:
I've fixed the link of my post above! -
Short update ... yesterday I asked or Chinese friends from Alie to send a HLK module to our test friend.
I also did an insulation test with 1000 Volt. The test shows more than 1000 MOhm between ac and dc. So far so good.@Bertb said:
Short update ... yesterday I asked or Chinese friends from Alie to send a HLK module to our test friend.
I also did an insulation test with 1000 Volt. The test shows more than 1000 MOhm between ac and dc. So far so good.:+1:
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Not a big fan of soldering SMD components and I cannot find standard components, how essential is the 2nd fuse and varistor on the 5v side?
@Atomfire said:
Not a big fan of soldering SMD components and I cannot find standard components, how essential is the 2nd fuse and varistor on the 5v side?
We are trying to make it as safer as possible... Assuming such modules will stay in a wall box, very close to wires and/or other potential fireable materials, we should try to mitigate risks as much as possible.
As I mentioned above --- This is DIY, also means 'risk it yourself'. Don't tell your insurance company ;-)
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@Atomfire said:
Not a big fan of soldering SMD components and I cannot find standard components, how essential is the 2nd fuse and varistor on the 5v side?
We are trying to make it as safer as possible... Assuming such modules will stay in a wall box, very close to wires and/or other potential fireable materials, we should try to mitigate risks as much as possible.
As I mentioned above --- This is DIY, also means 'risk it yourself'. Don't tell your insurance company ;-)
@rvendrame said:
@Atomfire said:
Not a big fan of soldering SMD components and I cannot find standard components, how essential is the 2nd fuse and varistor on the 5v side?
We are trying to make it as safer as possible... Assuming such modules will stay in a wall box, very close to wires and/or other potential fireable materials, we should try to mitigate risks as much as possible.
As I mentioned above --- This is DIY, also means 'risk it yourself'. Don't tell your insurance company ;-)
That is why I prefer to use fuses that blow, like the ones I mentioned earlier.
The resettable fuses also get warm. Can't wait for the package from Conrad to arrive. I am dying to do some further testing.With respect to the brave HLK ... it is on for some three days and it is stable.
