3 ms·

It feels like it is over-engineered. If a cheaper charger does the job (assuming it's not so cheap it violates safety regs) isn't this a case of over-optimisati

by wr1472 14y ago

It feels like it is over-engineered. If a cheaper charger does the job (assuming it's not so cheap it violates safety regs) isn't this a case of over-optimisation? PS: I'm not an electronics engineer so please educate me, on why this "filtered" and "cleaner" power supply is necessary to charge a phone?

kens 14y ago
Bad power really messes with the touch screen. Capacitive touch screens need to sense pico-Coulombs of charger, and this is really hard when the power supply (and the display) create tons of noise. This is a bigger problem as phones get thinner because it's harder to shield the touch screen. For details, see http://www.cypress.com/touch/Noise_Wars_Projected_Capacitance_Strikes_Back.pdf http://www.cypress.com/touch/Noise_Wars_Projected_Capacitanc... My totally hypothetical theory is that Steve Jobs tried a prototype charger, the touch screen didn't work well, and he said to do whatever is necessary to make sure that didn't happen again. (edit: more info)
- av500 14y ago
  but that does not help if the customer buys a 2nd 5$ charger and uses that e.g. at work. Then the touchscreen will behave less good and the customer will blame Apple...
  - koide 14y ago
    I doubt the customer will blame apple if all that's changed is the new $3 charger.
georgieporgie 14y ago
They link to another tear-down of a fake charger that takes potentially dangerous shortcuts. Also, it generates noise which can interfere with the touch-screen. http://www.arcfn.com/2012/03/inside-cheap-phone-charger-and-why-you.html http://www.arcfn.com/2012/03/inside-cheap-phone-charger-and-...
- deleted 14y ago
  [deleted]
- alter8 14y ago
  I submitted that 1 month ago - http://news.ycombinator.com/item?id=3903705 http://news.ycombinator.com/item?id=3903705 - and my nick ranit8 has been killed. I found a possible reason yesterday, it was a duplicate of http://news.ycombinator.com/item?id=3699293 http://news.ycombinator.com/item?id=3699293 Damn, you are dead since 3 days thanks to this: http://news.ycombinator.com/item?id=4027951 http://news.ycombinator.com/item?id=4027951 . And you are much more active than I am.
pranjalv123 14y ago
Noisy power supplies interfere with capacitive touchscreens so you can't use the phone while it's charging.
superuser2 14y ago
Not necessarily the case here, but "go with the cheapest thing that doesn't violate regulations" tends to get combined with "this regulation is inconvenient, let's get rid of it - if it were actually unsafe, nobody would do it" which doesn't end well for anyone (except, maybe, the lawyers).
shimon_e 14y ago
Apple probably doesn't care about the 1c saving by cutting component to bare requirements to be safe. Also you need to include the engineer's time.

by wr1472 14y ago

kens 14y ago

Bad power really messes with the touch screen. Capacitive touch screens need to sense pico-Coulombs of charger, and this is really hard when the power supply (and the display) create tons of noise. This is a bigger problem as phones get thinner because it's harder to shield the touch screen. For details, see http://www.cypress.com/touch/Noise_Wars_Projected_Capacitance_Strikes_Back.pdf http://www.cypress.com/touch/Noise_Wars_Projected_Capacitanc... My totally hypothetical theory is that Steve Jobs tried a prototype charger, the touch screen didn't work well, and he said to do whatever is necessary to make sure that didn't happen again. (edit: more info)

av500 14y ago
but that does not help if the customer buys a 2nd 5$ charger and uses that e.g. at work. Then the touchscreen will behave less good and the customer will blame Apple...
- koide 14y ago
  I doubt the customer will blame apple if all that's changed is the new $3 charger.

georgieporgie 14y ago

They link to another tear-down of a fake charger that takes potentially dangerous shortcuts. Also, it generates noise which can interfere with the touch-screen. http://www.arcfn.com/2012/03/inside-cheap-phone-charger-and-why-you.html http://www.arcfn.com/2012/03/inside-cheap-phone-charger-and-...

deleted 14y ago
[deleted]
alter8 14y ago
I submitted that 1 month ago - http://news.ycombinator.com/item?id=3903705 http://news.ycombinator.com/item?id=3903705 - and my nick ranit8 has been killed. I found a possible reason yesterday, it was a duplicate of http://news.ycombinator.com/item?id=3699293 http://news.ycombinator.com/item?id=3699293 Damn, you are dead since 3 days thanks to this: http://news.ycombinator.com/item?id=4027951 http://news.ycombinator.com/item?id=4027951 . And you are much more active than I am.

pranjalv123 14y ago

Noisy power supplies interfere with capacitive touchscreens so you can't use the phone while it's charging.

superuser2 14y ago

Not necessarily the case here, but "go with the cheapest thing that doesn't violate regulations" tends to get combined with "this regulation is inconvenient, let's get rid of it - if it were actually unsafe, nobody would do it" which doesn't end well for anyone (except, maybe, the lawyers).

shimon_e 14y ago

Apple probably doesn't care about the 1c saving by cutting component to bare requirements to be safe. Also you need to include the engineer's time.