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How do I buy quality external power supplies ("Adapter"/"Wall wart") from China?

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John_doe:
First, kindly look at the little flag next to where it says "Country" on the left. That tiny image means that I am not as privileged as someone living in some other parts of the world. Here, when you buy locally, you usually get the same cheap crap from China, only it costs about 10 times as much.

I'm also asking in general but more so for a specific case: Currently I'm advising some guy on a forum about something related to electronics. He does not have any electricity or electronics knowledge or skills. He needs a low power 10V adapter. 300mW will be more than apt.
AliExpress (and probably eBay too) is full of options, like this one for $2.49 USD:
https://www.aliexpress.com/item/32961533195.html

But as someone who has had a lot of experience with these kind of adapters, I don't trust them at all. I really don't want the guy to burn down his house because of my advice.
But where can I find something safe (and preferably accurate + not too noisy) in a sane price range?
If I'm any judge of a good circuit (as much as you can from a photo), then this module for $2.3 is actually kind of nice (and the reviews also support my opinion):
https://www.aliexpress.com/item/4000391310693.html


But the aforementioned man can't solder wires, nor would I want him anywhere near the "business end" of 230VAC.

Right now my best option is to advise him to buy this somewhat external 12V module and hope the adjustment pot can take it down to 10V:
https://www.aliexpress.com/item/1005003135918220.html

But I really don't like this option. For a whole slew of reasons.


So... Any advice?

NiHaoMike:

--- Quote from: John_doe on February 20, 2022, 10:41:02 am ---I'm also asking in general but more so for a specific case: Currently I'm advising some guy on a forum about something related to electronics. He does not have any electricity or electronics knowledge or skills. He needs a low power 10V adapter. 300mW will be more than apt.

--- End quote ---
Get two cheap but good quality 5V phone chargers and make a cable to connect them in series. Show him this video explaining how to solder, an electronics hobbyist who doesn't know how to solder is not going to get very far beyond plugging together Arduino stuff.

John_doe:
Not sure if you were joking or not, but I didn't mean that kind of electronics, more like consumer electronics, you know - plug sockets to jacks and such.
Also aside from my current case, I'd really like to know the answer for other times I had different situations which required a good quality adapter.

mariush:
10v 0.3W is very low amount.  That's basically less than 50mA

For such a low power requirement there are PCB mountable transformers
You could advise him to get a 9v AC transformer, rectify it using a bridge rectifier and a capacitor to around 12v then use a generic linear regulator like LM317 to get exactly 10v.

As an example, let's take this 9v 111mA (1w) transformer that costs 2$ : https://www.tme.com/il/en/details/bv302s09010/pcb-transformers/zettler/
So you add a bridge rectifier or 4 diodes to rectify the 9v ac to DC, add a capacitor (if we aim for max 50mA and minimum 11v we're looking at  C = Current / 2 x ac frequency x (peak dc voltage - minimum dc voltage)  = 0.05 / ( 2 x 50 x (11.5v- 11v) = 0.05/50 = 0.001 Farads or 1000uF so let's go with a 1500-2200uF capacitor)  then use a lm317 or some other linear regulator to get 10v.
 
He could power it using a 12v wall wart and put a linear regulator on the board to regulate 12v down to 10v ... at 30mA or whatever, no need to worry about heatsink-ing any regulator.
You can buy some wall wart power supplies for 3$ .. 3.5$ if you want them with barrel jack connector : https://www.tme.eu/en/details/zsi12_0.3-p/plug-in-power-supplies/espe/
... and they have certifications and more likely to be better built than aliexpress / ebay power supplies.

Alternatively, use a generic 5v phone charger and a boost (step-up) regulator to obtain 10v ... step-up boards are like 1-2$ on eBay (using super common chips that boost 3v or more to whatever voltage you set)

Karel:

--- Quote from: John_doe on February 20, 2022, 10:41:02 am ---First, kindly look at the little flag next to where it says "Country" on the left.

So... Any advice?

--- End quote ---

First, kindly look at the little flag next to where it says "Track Orders" on the top right:

https://il.farnell.com/



https://www.digikey.co.il/en


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