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USB power supply puts 220 Mains power out on USB jack

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Re: USB power supply puts 220 Mains power out on USB jack

#151

Post by rlpb »

sitharus wrote: post #8
0xffff2 wrote: post #7

Can someone explain why the transformer is on the DC side of the circuit in the diagram he draws at the beginning of the video?

This is a switch mode power supply. In order to use a smaller transformer it uses very high frequency AC rather than 50/60Hz mains frequency. In order to do this it rectifies the mains input to high voltage DC (330/220Vish, depending on the mains voltage) then using a power transistor rapidly switches this on and off at around 1-10kHz. Then the transformer outputs low voltage AC which is re-rectified and filtered to…

> the chip runs on 5v or similar

How does the chip get 5V, out of interest? Given that it's not allowed to be connected to the non-isolated side?

Re: USB power supply puts 220 Mains power out on USB jack

#152

Post by calgoo »

lucaspiller wrote: post #145
basicplus2 wrote: post #111

A true isolation transformer has an earthed copper shield wound in between and physically separating the primary from secondary windings, anything less is unsafe. One of the many reasons I detest "double insulated" equipment, as it is impossible to determine if it has been designed for safety or not without ripping it apart and destroying it. This is a real issue in Australia as our regulators do no regulating and mo…

> even though manufacturers lie and put standards compliance numbers on them The CE marking in Europe is the same (in most cases). It just means that the manufacturer declares it is compliant, not that it has been approved and tested by anyone. https://en.wikipedia.org/wiki/CE_marking

I found that at least in the past, the S markings from Sweden where quite good. Now, I have not been back for 20 years so no idea if it still valid...

Re: USB power supply puts 220 Mains power out on USB jack

#153

Post by hatsunearu »

jklp wrote: post #66

Not sure if HN knows about Mehdi Sadaghdar's (aka ElectroBOOM's) YouTube channel, which is somewhat similar - but takes a more lighthearted view on electronics. E.g. Compare Big Clive's mention of a full bridge rectifier in the video vs Mehdi's YouTube video of the same thing :) https://youtu.be/sI5Ftm1-jik

Man, I know I shouldn't have taken his videos seriously, but I got a little careless playing with my Nixie Tube Clock project with 170Vdc on it, thinking that it wouldn't hurt me.

It hurt A LOT. Granted, my hand was wet a little, but man it fucking hurt.

Re: USB power supply puts 220 Mains power out on USB jack

#154

Post by basicplus2 »

basicplus2 wrote: post #146
mavhc wrote: post #113

Earlier quoted context omitted.

Does the Australian Standards body require that devices are sent to them for testing? Then there could be a database you could check as to whether a device has passed.

technically yes.. but it is not enforced

I should also add that if you are an Australian manufacturer, you have to submit your product for testing for design compliance and you won't last long if you dont, but importers can import anything with none, yet another impediment to Australian manufacturing.

Re: USB power supply puts 220 Mains power out on USB jack

#155

Post by HeyLaughingBoy »

makomk wrote: post #53
cm2187 wrote: post #19

Earlier quoted context omitted.

Including sexual lubricants https://www.youtube.com/watch?v=5i7_-NtJeB4 Someone has to review them...

From Poundland, which - for any non-Brits who haven't come across it - is our more upmarket equivalent of a dollar store and sells all kinds of interesting items that he's done videos about.

Poundland? Sex lubricant? The marketing just writes itself...

Re: USB power supply puts 220 Mains power out on USB jack

#156

Post by HeyLaughingBoy »

paddy_m wrote: post #61
yoodenvranx wrote: post #38

Earlier quoted context omitted.

If you are into machining then check out Clickspring, oxtoolco, Abom79, Keith Rucker, Keith Fenner, Shadow HKW, ... If this is not enough then go and visit this list: https://www.reddit.com/r/ArtisanVideos/comments/3v264a/meta_... (But be careful, this is the ultimate rabbit hole)

Keith Fenner is astounding. Years ago my girlfriend said "enough Keith Fenner videos, You have to take a welding class", I did and it was amazing. As a side note, I'm starting a blog where I interview heavy equipment operators and write about heavy equipment. Anyone here interested in that?

Fuck yeah.

Um, I mean, yes. Yes, I am interested.

Re: USB power supply puts 220 Mains power out on USB jack

#157

Post by sitharus »

rlpb wrote: post #151
sitharus wrote: post #8

Earlier quoted context omitted.

This is a switch mode power supply. In order to use a smaller transformer it uses very high frequency AC rather than 50/60Hz mains frequency. In order to do this it rectifies the mains input to high voltage DC (330/220Vish, depending on the mains voltage) then using a power transistor rapidly switches this on and off at around 1-10kHz. Then the transformer outputs low voltage AC which is re-rectified and filtered to…

> the chip runs on 5v or similar How does the chip get 5V, out of interest? Given that it's not allowed to be connected to the non-isolated side?

Normally though an additional winding on the transformer.

Switch mode transformers have three or four sets of windings. The primary (high voltage), secondary (low voltage) a bootstrap winding (for the chip) and sometimes a flyback winding.

The bootstrap winding takes off a variable voltage depending on the local supply and uses a linear regulator to produce the required voltage.

For a better explanation than I can manage in text the EEVBlog channel goes in to all sorts of regulators and how they work: https://www.youtube.com/watch?v=cM7t1Mpu7s4&list=PLn-ZIFhWxh...

Re: USB power supply puts 220 Mains power out on USB jack

#158

Post by ktRolster »

DanBC wrote: post #116
ktRolster wrote: post #106

Earlier quoted context omitted.

I think that video has been sped up somewhat....

Why do you think it's sped up? There's surprising amounts of skill in these unskilled / semi-skilled jobs. If you're sitting at a machine winding transformers for 8 hours a day, and paid for each item you make (and fined for each item that fails test) you quickly get faster at winding transformers.

  >Why do you think it's sped up?
Primarily because of the extreme precision when moving the arm over a long distance

Re: USB power supply puts 220 Mains power out on USB jack

#159

Post by otsdr »

jklp wrote: post #66

Not sure if HN knows about Mehdi Sadaghdar's (aka ElectroBOOM's) YouTube channel, which is somewhat similar - but takes a more lighthearted view on electronics. E.g. Compare Big Clive's mention of a full bridge rectifier in the video vs Mehdi's YouTube video of the same thing :) https://youtu.be/sI5Ftm1-jik

I much prefer Clive's joke-to-useful info ratio.

Re: USB power supply puts 220 Mains power out on USB jack

#160

Post by k_sze »

seany wrote: post #28
yoodenvranx wrote: post #5

Earlier quoted context omitted.

Big Clive is _the_ channel for teardowns of everyday electronic stuff. I am actually not that interested in this kind of stuff but somehow I still watch most of his videos. If you are into more... entertaining teardowns you should have a look at AvE. Even if you don't like it you will still learn some useful canadian terms ;) (edit: just to make it clear, AvE is actually very knowledgable. His "boltr" teardown series…

Mikes electronic stuff is also quite good.

You mean this? https://www.youtube.com/user/mikeselectricstuff
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