Are Chinese power supply chargers that dangerous to use ?

[ahmedadelhosni]

@petewill Thanks a lot. I actually read all the replies in your thread and I now understands safety requirements better than before.

Waiting for your great projects :)

[petewill]

@ahmedadelhosni It is a long thread :)

I am torn between all the projects on my list. I thought I would have more time this winter but so far that hasn't been the case. I am still hoping to get to this one soon but a few others have taken priority :(

[icebob]

Hi,
3 weeks ago I ordered some $0.99 USB power supply from Aliexpress: http://www.aliexpress.com/item/Hot-5V-2A-Travel-Convenient-EU-Plug-Wall-USB-Charger-Adapter-For-Samsung-galaxy-S5-S4/32362543740.html

Today arrived. I opened and I think it is not bad, isn't it?

[ahmedadelhosni]

@icebob After I have read almost most of the replies in the thread "safe in wall ... " I would tell you don't ever use this. This is even worse that charger number 1 and 2 which I posted above.

After reading about safe circuits. The idea is that you need to protect all your component from damage and to avoid any overheating + you want a clean steady output.

What i see now that there is no fuse nor varistor components at the AC input. The circuit uses only one diode for rectifying - the one at the upper right - not too bad but I read that a full wave rectifier with four diodes gives cleaner output. Other good circuits have an IC to control the output with feedback and has inbuilt over voltage / over current / over thermal protection. This one uses only transistor with - I guess - the other transistor for feedback. Another bad thing is that there is no isolation at all between high side voltage and low side voltage. The optocoupler in the middle should handle this in a better circuit desing, plus, there is no Y capacitor for isolation. ( See charger number 3, you will find an empty space in the middle and a blue component which is the Y capacitor )

Thus this is a really simple AC to DC charger but with less protection and probably won't provide you with stable voltage. I don't encourage you to use this. You can check the two threads in my origianl post. They use HLK which is a great circuit design as a step down converter.

[icebob]

@ahmedadelhosni thank you for you explanation. I won't use it.

[ahmedadelhosni]

@icebob you are welcome. I am not an expert but that is a breif of what I have understood after reading the thread safe in wall...

[epierre]

one led driver nearly exploded through my head once ... some vendors are now showing this:
http://www.aliexpress.com/item/100-genuine-Original-2A-EU-Plug-Wall-Charger-USB-Power-Adapter-Travel-For-Samsung-S4-I9500/2048345033.html

[m26872]

@epierre Hehe. The "fake" one looks really good compared to the one @icebob showed us. IC, fuse and big trafo.

Interesting design choice to squeeze the electrolytic cap between mains input btw. 😰

[ahmedadelhosni]

@m26872 hehehe yeah right :) Actually I can't see an IC in the original one while the fake one has IC and fuse :D maybe hidden at the back or something. but 9$ are a lot though.

[RoDl]

Hello, is this Samsung USB charger fake or real ? It was purchased in retail store, not eBay...