Woohoo! 32k achieved!!! Finally I can post some new rant without risking some sudden overshoot 😁

So putting celebrations aside for a minute, a while ago I've noticed a tingle when I stroke my finger across metal areas of my tablet, or the sides of my phone (which probably has metal near it too) while it's charging. And it's been bugging me ever since.

Now, some things to note are that it only happens when my feet are touching the ground though slippers, and that the frequency is so low that I can actually feel the tingle when I slide my finger across the material. This to me at least seems like electricity flows through me into ground, and touching the ground directly provides a path so easy for the electrons to run away that I don't feel it at all. But if I lift my feet off the ground entirely, I just get charged up and after that, nothing else happens.

So those are my ideas. The answers on the subject on the other hand.. absolute cancer. Unsurprisingly, most of them came from Apple users. Here's some of them.

https://discussions.apple.com/threa...
- I've not noticed it, but if you're concerned bring the phone to Apple for evaluation.
- Me too facing same problem.. did u visit apple care?
And one good answer at least...
- google emf sensitivity, its real. You are right, there is a small current flowing through your body, try to limit your usage. The problem with this issue is those who aren't affected (lucky ones for now) will tell you these products are 100% safe. To a degree they are, i used my ipod touch for about 2 years straight vwith virtually no symptoms. then the tingling started and it gets worse.You will get more sensitive to progressively less powerful things. I dont want to scare you but just limit your usage like i didnt do 🙂

Overall that discussion was pretty good actually, aside from "bring it to the Genius Bar, they'll know for sure and not just sell you another unit". But then there's Reddit.
https://reddit.com/r/iphone/...
- Ok, real reason is probably that the extension cord and/or outlet is probably not grounded correctly. Either that or you are using a cheap knockoff charger.
Either use a surge protector and/or use the authentic Apple Charger.
- It's not the volts that hurt you, it's the amps
- I think you are in deep love with your phone. That tingling sensation is usually referred to as "love" in human language.
- Do less acid, I would advise.

Okay, so that's the real cancer. Grounding issue sounds reasonable despite it being wrong. Grounding is actually not needed when your charging appliance doesn't have any exposed metal parts. And isolation from high voltage to low voltage side actually happens through things like routering holes into the PCB, creating spark gaps, and using galvanic isolation through things like optocouplers. As for a surge protector? I'm using them to protect my PC and my servers, but the only purpose they serve is to protect from.. you guessed it.. voltage surges, like lightning bolts hitting the grid. They don't do shit for grounding or reducing this tingle! What a fucking tool.

It's not the volts that kill, it's the amps.. yeah I'm sure that the debunking of that is easy to find. Not gonna explain that here. And the rest of it.. yeah it's just fucking cancer.

Now what's the real issue with this tingle? It's actually a Class-Y rated (i.e. kV rated) capacitor that's on the transformer of any switch-mode power supply, including phone chargers. If memory serves me right, it helps with decoupling the switching noise and so on. But as it's connected to the primary side of the transformer, if the cap is sufficiently large and you are sufficiently sensitive, it can actually cause that tingle by passing a fraction of the mains electricity into your body. It's totally safe though, as the power that these caps pass is very small. But to some, it's noticeable.

Hope you found this interesting! And thanks a lot for bringing me to 2^15. I really appreciate it ♥️

Yet another rant about crappy electronic designs.

Just now I was cleaning my desk and stumbled upon some old hard drive in a caddy that I still had laying around.. I figured, let's plug it in and see whether the drive still works. And to some extent, it does! Except that every few minutes it craps out on me. And after disassembling the caddy, I think that I know why.

Just as background information, hard drives work at 12V and generally require about 10W to spin their motor. Meanwhile USB operates at 5V. So a boost converter needs to be present in the controller to step up the voltage and power the drive.

Now what's a boost converter? It's an inductor, a capacitor, a transistor and a diode in a specific arrangement (if you're interested in the design, check out https://youtube.com/watch/...), along with feedback circuitry to stabilize output voltage. Now that transistor is important.. it switches at very high frequency, and its rise and fall times create heat. In the particular transistor used in that controller, it apparently causes the transistor to operate at 65-68°C. That's quite toasty IMO, and overheating may be why the controller is so unstable. But the Chinese manufacturers thought that it's just fine and okay to be sold without heatsink or some research into transistors with better rise and fall times.

So the hard drive craps out on me and yet again it's because of certified shitdesigns. MOTHERFUCKTURERS!!!!