[NavinF]

> "Experts say it cannot be done; amateurs accomplish it every day."

I love this because I seem to encounter situations like that every day. Who came up with this saying?

Recent example: This guy asked a very simple question about something that's commonly done in industry (wiring two power supplies in parallel and balancing the current between them): https://www.reddit.com/r/AskElectronics/comments/1g84zd7/usi...

Literally 95% of the replies in that thread are irrelevant bullshit from "experts" that have no idea how redundant server PSUs work. I replied to some under the same username. Meanwhile another guy successfully wired two 100W USB-C ports in parallel to power an entire PC. He had no idea that the resistance of his crappy wires kept the two smps control loops stable and divided the current evenly between the two ports ensuring that neither one trips OCP: https://www.reddit.com/r/UsbCHardware/comments/1g8pser/let_m...

[baq]

I guess there's the armchair expert and the actual, real expert and these two are completely different beasts.

I wouldn't feel comfortable with this guy's usb-c setup but probably not for 'it's all going to burn down' reasons, more like 'the connection will get loose somewhere and I'll lose my work'.

[NavinF]

He posted the photos as soon as he got it working; It's obviously not his permanent setup. My point is that he posted it on the same day that ~60 people claimed this was somehow a difficult task.

[bambax]

> Who came up with this saying?

I was not aware of that specific formulation but there's a maxim by Mark Twain that says "They did not know it was impossible so they did it".

[Workaccount2]

Since I actually work in this field:

Redundant switching power supplies are purpose built to be redundant. They usually have a current share circuit (to balance the load) and output diodes (to stop one supply from feeding the other one). Without that one supply will "over power" the other, fill it's output caps, and then the feedback of that supply will go "Hey the output caps are charged so why do I need to do anything!?". You end up with an erosion of power balance.

You are riding a pretty high horse, but the commenters in that thread are not wrong and if you think cheap 5V USB chargers are anything like redundant server PSU's. I don't think putting random USB chargers in parallel will cause a fire or anything, but it's just needlessly bad engineering that will be anything but robust.

A programming analogy to help people here: You can write a program that is tens of thousands of lines of if statements. It might probably work maybe for some inputs? But damn if it not bad engineering. No one would ride around on the high horse of "See the program worked! The "experts" were wrong!".

[NavinF]

The linked post shows why all that is unnecessary. Paralleling PSUs is so easy that people get it working by accident.

> You end up with an erosion of power balance

Unlike you, the guy powering his PC with two USB-C ports quantified how imbalanced it is. 65W+75W in his photo.

>tens of thousands of lines of if statements

Terrible example because that takes more work than the correct solution. btw the correct solution in this case involves FETs, not diodes. Look up "ideal diode circuit"

[vasco]

"Random person on reddit" doesn't qualify as experts.

[NavinF]

Everyone in that thread pretended to be an expert despite being clueless. This is normal, but you'd only notice it if you're familiar. Also see Gell-Mann amnesia effect

[jijan]

Amsyar hensem

[NavinF]

who?