Electronics > Beginners
USB charger problem - live cable
Jeroen3:
Won't help much if the phone has any metal parts. Or headphones with metal.
And some capacitive touchscreens are inoperable with this 50 Hz hum on them.
I'd toss the charger. Such a low 5W supply shouldn't be giving a noticable tingling. Only measurable.
Whales:
--- Quote from: Jeroen3 on February 01, 2020, 11:05:44 pm ---Won't help much if the phone has any metal parts. Or headphones with metal.
And some capacitive touchscreens are inoperable with this 50 Hz hum on them.
I'd toss the charger. Such a low 5W supply shouldn't be giving a noticable tingling. Only measurable.
--- End quote ---
50Hz shouldn't effect the touchscreen scanning, much higher frequencies (ie switching noise, higher-freq interference from mains dimmers) would be the culprits in that situation.
Using larger Y caps adds more tingle but is otherwise not a reliable indication of a charger being "lower" or "higher" quality. In fact larger Y caps (more tingle) suggest there might better noise suppression, but really this depends on the whole design (not just one part).
Lee697: The only reliable methods of determining whether or not a charger is a good one are not are (1) extensive testing and (2) disassembly to inspect the design. There are lots of forum topics, blog posts and videos on the latter (inc by Dave). Again: tingling from Y-caps is not an indication of charger quality or safety.
Car analogy: should you buy the car with the louder/quieter horn because it's safer? No, you need to consider the whole car when judging safety, not just the horn. A loud or quiet horn may be annoying, but it's not an overall indicator of quality or safety.
wraper:
--- Quote from: Jeroen3 on February 01, 2020, 11:05:44 pm ---Won't help much if the phone has any metal parts. Or headphones with metal.
And some capacitive touchscreens are inoperable with this 50 Hz hum on them.
I'd toss the charger. Such a low 5W supply shouldn't be giving a noticable tingling. Only measurable.
--- End quote ---
Really? 0.2mA is completely acceptable (calculated from voltage drop over 10k resistor). And these days chargers have way more than 5W rating. One in question has 17W rating.
tooki:
--- Quote from: Jeroen3 on February 01, 2020, 11:05:44 pm ---Won't help much if the phone has any metal parts. Or headphones with metal.
And some capacitive touchscreens are inoperable with this 50 Hz hum on them.
I'd toss the charger. Such a low 5W supply shouldn't be giving a noticable tingling. Only measurable.
--- End quote ---
:-DD
Then you’re limiting yourself to cheap, dangerous, non-compliant Chinese crapola chargers. The suppression caps in any properly made charger are enough to be tingly sometimes.
wraper:
--- Quote from: tooki on February 02, 2020, 10:19:46 am ---Then you’re limiting yourself to cheap, dangerous, non-compliant Chinese crapola chargers. The suppression caps in any properly made charger are enough to be tingly sometimes.
--- End quote ---
Nokia chargers from the past did dot have this noise suppression cap. IIRC they used shielding between windings. And it worked fine even with phones having capacities touchscreens. If regular transformer is used without Y cap between primary and secondary sides, capacitive touchscreens of connected devices will simply stop working or will have very erratic behavior.
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