Top notch Chinese 5V 1A PSU - Page 1
Forum section: electronics / general

author: itdontgo
author_rank: Regular Contributor
timestamp: July 30, 2012, 08:10:48 am
content: Look at this little beauty. That's a 2.2uF filter cap there with single diode rectifier with a single transistor oscillator and transformer driver.The output rectifier is the best 1N4148 in the world as this one can do an amp. In fact they seem to be a fan of the 1N4148 as it features twice in the HV section....and the whole thing is broken!

author: T4P
author_rank: Super Contributor
timestamp: July 30, 2012, 08:51:38 am
content: I see 1N400X's as output rectifiersLove the sarcasm there

author: Rerouter
author_rank: Super Contributor
timestamp: July 30, 2012, 10:04:55 am
content: looking at that image, i have to ask if the input caps are rated for rectified AC voltage?

author: itdontgo
author_rank: Regular Contributor
timestamp: July 30, 2012, 11:21:44 am
content: Quote from: T4P on July 30, 2012, 08:51:38 amNo that's the input recifier; output diode is a 1N4148. The input from the mains is a 1N4007! I'm amazed it's a 4007 when they could have scrimped on a 4004. It's not like they're looking for longevity or safety with this thing.What really amazes me about this kind of product is that whoever designed such a cheap and basic circuit must also know that it really isn't up to the job. Designing a 1-transistor switch-mode that works a million times over for pennies can't be that easy.

author: itdontgo
author_rank: Regular Contributor
timestamp: July 30, 2012, 11:22:35 am
content: Main cap is 400v and 105C!

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 30, 2012, 12:19:37 pm
content: mikeelectricstuff did a teardown and performance check video. this thing is excel and meant to.... cheap and irreducibly complex for non feedback single transistor smps. and not least... produced in millions infecting earth. cant blame the designer, the nature of "the harmonics of world economy" and the buzz of "portable devices" demands this kind of cheap stuffs.

author: SeanB
author_rank: Super Contributor
timestamp: July 30, 2012, 03:59:55 pm
content: I think all those components are fake as well, rebranded diodes and suspect capacitors from MisterLee down the load cleep cheep

author: OndraSter
author_rank: Contributor
timestamp: July 31, 2012, 12:05:41 am
content: That's some bad luck you are all having. I bought about two years ago cheap USB hub for $4 that had external power supply. It has got two, yes, TWO!! tranzistors, three elytes, many diodes...What I don't think is a good is that "9.5V - 4.5V, 800mA max" on the sticker

author: ftransform
author_rank: Frequent Contributor
timestamp: July 31, 2012, 01:22:34 am
content: I wish they could get even more ghetto

author: nitro2k01
author_rank: Frequent Contributor
timestamp: July 31, 2012, 02:59:59 am
content: idontgo, your PSU is exactly the same as the one Mike torn down. Here's the video:OndraSter: Yours is an engineering dream in comparison. A full wave rectifier on the input! What a luxury...I must also commend the people building this PSU for deciding to further minimize the creepage distance by letting the component öead reach out against the secondary side. That's such a brilliant and cheap optimization for minimizing the creepage distance!

author: SeanB
author_rank: Super Contributor
timestamp: July 31, 2012, 04:49:55 am
content: My one did only work for one cycle of the mains..........

author: itdontgo
author_rank: Regular Contributor
timestamp: July 31, 2012, 05:25:45 am
content: That's right it came with that crappy USB hub. My mouse kept going off when I checked the PSU it was at 0v.I'm actually moderately impressed at the economy of it considering it does actually work up to 100mA.What's really annoying is that you cant buy a USB hub anymore without it being junk. I've gone through lots of them and they never work. When you open them up they're always badly made and have hardly any passive components.

author: SeanB
author_rank: Super Contributor
timestamp: July 31, 2012, 03:35:24 pm
content: The best I bought were made by Belkin, quite good quality when I looked inside. Even has 2 PTC fuses, one per pair of outlets as well.

author: FenderBender
author_rank: Super Contributor
timestamp: August 11, 2012, 04:23:34 am
content: Got this beauty with my new cell phone off eBay.

author: amyk
author_rank: Super Contributor
timestamp: August 11, 2012, 08:25:31 am
content: I think the electrical design is basically sound, these could do their nameplate ratings if they used better components and physical design. Efficiency is another matter though.