Joe Doakes from Como Park emails:
My Android cell phone makes a noise when I plug it into the charger, kind of a “boink-boink” sound. I plugged it in at work, a few minutes ago. Worked fine, then started making that noise. Quit now. Never does it at home.
I suspect power fluctuations in this building. I bet every time somebody starts a microwave down the hall, my cell phone senses the power drop and thinks it’s been unplugged, then immediately senses the power rebound and thinks it’s been plugged back in. boink-boink. Boink-boink.
I mentioned to a buddy who is a Master Electrician. He says:
“More likely power factor issues. The power factor is screwed up by all the fluorescent lights and computers. Those are shifting the power so that voltage sine is out of phase with the amperage sign. That’s the power factor. AC electricity flows in a sine wave, if all is well. When a coil load or capacitor load is introduced the impedance and/or reactance will shift the power out of phase with itself. One shifts the voltage forward, one shifts the amperage forward. As they get out of phase the amperage has to go up to compensate for the loss of actual power because the voltage times amperage of the power as it is actually used is not the same as the multiple of each measured separately. Yes the voltage measured is 120 and amperage measured is 10, but they don’t reach those points simultaneously. As a function of simultaneous use when voltage is 120 amperage is only 9.7 and when it reaches 10.3 the voltage is already sliding back down to 116.5. Your phone and charger may be sensing that.”
Not power fluctuation, power factor. Well, that’s me told, then.
Joe Doakes
one of the scariest days of my life – in a completely unrelated story – when I was when I have an electrician over to my house to look at a circuit that was acting funny. He took it apart, and said “you’re lucky to be alive”.
Good thing I didn’t have a self on the plug into it!
Not quite sure that’s true; the classic “dummy” power supply simply has a lot of spikes and puts a lot of 3rd, 5th, and 7th harmonics (180, 300, 420 Hz) and noise onto the lines, which in turn overloads wiring without the electrician seeing a lot of current at 60Hz. Switching mode power supplies (the current standard/requirement) are supposed to alleviate some of this, but I believe that’s the problem.
What your electrician is talking about, power factor, is actually usually associated with inductive loads like motors. I would be surprised if there was enough inductance or capacitance in a power supply to throw off power factor much.
So yes, DC power supplies can throw things off electrically, but I’m not sure the electrician named the problem correctly. It’s also worth noting that one big reason for electrical problems in houses are amateur electricians who will do stupid stuff like miswiring hot, neutral, and ground. Overseas it can be worse; a colleague of mine in Thailand tested the 110V circuits in a factory there, and found that all of them were dangerously miswired–hot and neutral (white and black) switched, neutral swapped with ground, etc..
My family owns my grandparents farm. Rents out the fields and we maintain the buildings and yard. Everytime I go into the empty (but maintained) house, and turn on some lights, I think to myself “the wiring was put in here around 1920, probably never worked on since then”. I’ve stayed overnight there a small number of times. I always bring 2 smoke detectors, sleep on the couch by the front door, and keep my shoes right by the door, in case I have to bolt out of there in a hurry.
I’m no Master Electrician, but I am a Ph.D. in EE.
I rather doubt the power factor explanation. I’ve had issues with that when we ran wind tunnels and the power company made us dump massive caps to correct the power factor (the wind tunnels are essentially massive motors so you need the C to counteract the L), but I’ve never seen power factor come into play in anything house sized or office building sized. Factories are different, but office buildings tend to be relatively benign. Not to say that a government building won’t do wacky things (one of the things the government is good at is assuming laws [both of man and of nature] don’t apply to them), of course, but it’s unlikely.
More likely it has more to do with your charger and phone. Some phones are more picky on power fluctuations on the USB line; Motorola phones are notorious for that. And most chargers, especially bargain chargers, don’t put out very clean power and that power quality gets worse as components age. And all of that assumes that your USB cable and connectors haven’t gotten worse with age.
If asked to guess, I’d take a 0.01% chance of PFC issues and the rest USB issues. And yes, I have designed USB chips so I’m pretty familiar with the games other folks play. cough, hack, cough
Aside: A couple houses ago I opened up a panel during a home inspection and said, “The guy who wired this up had a very bad day when he installed this.” Waaayyy too many scorch marks. I came later to realize he was more likely incompetent since I found half the outlets in the house wired up incorrectly.
Ditto what BB said (I think).
RE: ““you’re lucky to be alive” – Among the more fun days when I was an electrician was telling an occupant (homeowner or commercial tenant) either “who put this device (switch, light, etc) in, this is all screwed up!” or the old stand-by “you’re lucky to be alive”. It helped them accept the bill a little more easily when it came due – I was a ‘lifesaver’ after all.
Interestingly a tech just pulled this on me the other day. We switched phone service at home from one provider to another as we changed our cable-internet-phone service bundle. A few days after the switch over I noticed that the phone didn’t work. Turns out the installing tech failed to connect it. Now we don’t really even use the landline and in fact only have one wired telephone in the whole house, in the kitchen. But it was part of the “bundle” we are paying for and my spouse felt strongly that we were getting ‘ripped off’. So a second tech came out and after dicking around (technical term) for 45 minutes came in and told my wife that he had hooked up the phone but it would only work on the one jack in the kitchen because “whoever hooked this up before really screwed it up ’cause that’s what that company (his competitor) does.” My spouse was getting ready to argue and I told him: “Great. Thanks for coming out and hooking it up.” That evening I went out and within 5 minutes had every jack in the house working even though we only use the jack in the kitchen.
Get a power conditioner that puts out a “pure” sine wave and see if problem persists. Good ones are pricey.