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AliExpress LED power supplies - almost OK
It's kinda frustrating when you come across a design of a power supply that is really quite good, but then the manufacturer skimps on a few components that then makes the unit dangerous to use.
In this case it wasn't just the substitution of an important safety capacitor with an ordinary one, but also the corner cutting on the transformer that results in the mains voltage 120/240V primary being in physical contact with the low voltage secondary winding. If they'd used wire with thicker insulation or even just a bit of sleeving, then that risk could have been reduced massively.
That might not result in an immediate risk, but all it takes is something like an electrostatic discharge or time and heat related degradation to result in the output of the power supply becoming referenced to the mains input side. The scary bit being that the output will still put out 12V and everything will seem to work, but it will be referenced to the mains and capable of giving a bad shock.
If I found myself in a situation where I had no other power supplies, and it was a simple load like fixed LED lighting, then I would probably earth/ground the negative of the 12V output to ensure that any insulation breakdown could result in a proper fault current path to trigger protection and reduce the voltage that the output could rise up to.
I didn't do a load test on these supplies. But the power ratings of products like these are best treated as being "ambitious".
In summary
Pros:-
Nice case
Rugged terminals
Nice sensible circuit layout
Proper snubber network
Cons:-
Earth terminal is floating
Class Y capacitor substituted with ordinary one
No input noise filtering
Transformer lacking proper separation
Windings are copper coated aluminium
If you enjoy my videos enough to buy me a coffee or cookie, you can do so by supporting me on Patreon. I release videos without adverts for critique and feedback on Patreon as soon as they have been made. I also release Patreon-only backstage videos when I'm working on shows.
https://www.patreon.com/bigclive
Alternatively, for a single contribution you can use PayPal:-
https://www.paypal.com/paypalme/bigclive
#ElectronicsCreators
...
https://www.youtube.com/watch?v=MOAIm2crPYk
In this case it wasn't just the substitution of an important safety capacitor with an ordinary one, but also the corner cutting on the transformer that results in the mains voltage 120/240V primary being in physical contact with the low voltage secondary winding. If they'd used wire with thicker insulation or even just a bit of sleeving, then that risk could have been reduced massively.
That might not result in an immediate risk, but all it takes is something like an electrostatic discharge or time and heat related degradation to result in the output of the power supply becoming referenced to the mains input side. The scary bit being that the output will still put out 12V and everything will seem to work, but it will be referenced to the mains and capable of giving a bad shock.
If I found myself in a situation where I had no other power supplies, and it was a simple load like fixed LED lighting, then I would probably earth/ground the negative of the 12V output to ensure that any insulation breakdown could result in a proper fault current path to trigger protection and reduce the voltage that the output could rise up to.
I didn't do a load test on these supplies. But the power ratings of products like these are best treated as being "ambitious".
In summary
Pros:-
Nice case
Rugged terminals
Nice sensible circuit layout
Proper snubber network
Cons:-
Earth terminal is floating
Class Y capacitor substituted with ordinary one
No input noise filtering
Transformer lacking proper separation
Windings are copper coated aluminium
If you enjoy my videos enough to buy me a coffee or cookie, you can do so by supporting me on Patreon. I release videos without adverts for critique and feedback on Patreon as soon as they have been made. I also release Patreon-only backstage videos when I'm working on shows.
https://www.patreon.com/bigclive
Alternatively, for a single contribution you can use PayPal:-
https://www.paypal.com/paypalme/bigclive
#ElectronicsCreators
...
https://www.youtube.com/watch?v=MOAIm2crPYk
View all episodes
By bigclivedotcomIt's kinda frustrating when you come across a design of a power supply that is really quite good, but then the manufacturer skimps on a few components that then makes the unit dangerous to use.
In this case it wasn't just the substitution of an important safety capacitor with an ordinary one, but also the corner cutting on the transformer that results in the mains voltage 120/240V primary being in physical contact with the low voltage secondary winding. If they'd used wire with thicker insulation or even just a bit of sleeving, then that risk could have been reduced massively.
That might not result in an immediate risk, but all it takes is something like an electrostatic discharge or time and heat related degradation to result in the output of the power supply becoming referenced to the mains input side. The scary bit being that the output will still put out 12V and everything will seem to work, but it will be referenced to the mains and capable of giving a bad shock.
If I found myself in a situation where I had no other power supplies, and it was a simple load like fixed LED lighting, then I would probably earth/ground the negative of the 12V output to ensure that any insulation breakdown could result in a proper fault current path to trigger protection and reduce the voltage that the output could rise up to.
I didn't do a load test on these supplies. But the power ratings of products like these are best treated as being "ambitious".
In summary
Pros:-
Nice case
Rugged terminals
Nice sensible circuit layout
Proper snubber network
Cons:-
Earth terminal is floating
Class Y capacitor substituted with ordinary one
No input noise filtering
Transformer lacking proper separation
Windings are copper coated aluminium
If you enjoy my videos enough to buy me a coffee or cookie, you can do so by supporting me on Patreon. I release videos without adverts for critique and feedback on Patreon as soon as they have been made. I also release Patreon-only backstage videos when I'm working on shows.
https://www.patreon.com/bigclive
Alternatively, for a single contribution you can use PayPal:-
https://www.paypal.com/paypalme/bigclive
#ElectronicsCreators
...
https://www.youtube.com/watch?v=MOAIm2crPYk
In this case it wasn't just the substitution of an important safety capacitor with an ordinary one, but also the corner cutting on the transformer that results in the mains voltage 120/240V primary being in physical contact with the low voltage secondary winding. If they'd used wire with thicker insulation or even just a bit of sleeving, then that risk could have been reduced massively.
That might not result in an immediate risk, but all it takes is something like an electrostatic discharge or time and heat related degradation to result in the output of the power supply becoming referenced to the mains input side. The scary bit being that the output will still put out 12V and everything will seem to work, but it will be referenced to the mains and capable of giving a bad shock.
If I found myself in a situation where I had no other power supplies, and it was a simple load like fixed LED lighting, then I would probably earth/ground the negative of the 12V output to ensure that any insulation breakdown could result in a proper fault current path to trigger protection and reduce the voltage that the output could rise up to.
I didn't do a load test on these supplies. But the power ratings of products like these are best treated as being "ambitious".
In summary
Pros:-
Nice case
Rugged terminals
Nice sensible circuit layout
Proper snubber network
Cons:-
Earth terminal is floating
Class Y capacitor substituted with ordinary one
No input noise filtering
Transformer lacking proper separation
Windings are copper coated aluminium
If you enjoy my videos enough to buy me a coffee or cookie, you can do so by supporting me on Patreon. I release videos without adverts for critique and feedback on Patreon as soon as they have been made. I also release Patreon-only backstage videos when I'm working on shows.
https://www.patreon.com/bigclive
Alternatively, for a single contribution you can use PayPal:-
https://www.paypal.com/paypalme/bigclive
#ElectronicsCreators
...
https://www.youtube.com/watch?v=MOAIm2crPYk