How can this possibly work?

Post #425,406 by drook 9/8/18 7:38:33 PM 9/8/18 7:38:33 PM Reply	How can this possibly work? https://www.bhphotovideo.com/c/product/1226777-REG/sengled_eb_a19nae26w_everbright_1_pack.html Equipped with a built-in rechargeable battery, the Everbright 9W Bulb from Sengled is designed to keep your house lit during a power outage. The bulb uses smart circuitry to sense a power outage, and it will then automatically continue to provide illumination using power from an integrated lithium-ion battery. The smart circuitry is able to detect the difference between normal on/off operation and a power outage, so that the light will not automatically turn on when you have intentionally turned it off. Furthermore, once your power comes back on, the battery will automatically recharge using the bulb's standard power supply. The Everbright Bulb is a 9W lamp that emits up to 500 lumens of light. It features a color temperature of up to 3000K, and the bottom of the bulb is an E26 light base for compatibility with most light fixtures. Supposedly you can have this in a regular lamp or light fixture and turn it on and off like normal. If the power goes out, you can still turn it on via the switch. I get the battery backup, but how can it detect the difference between the switch being off and the power going out? -- Drew
Post #425,407 by boxley 9/8/18 8:58:25 PM 9/8/18 8:58:25 PM Reply	very well wordcrafted it carefully doesnt say it will automatically come on if the switch is in the off position and the power goes out. "Science is the belief in the ignorance of the experts" – Richard Feynman
Post #425,408 by drook 9/8/18 9:21:24 PM 9/8/18 9:21:24 PM Reply	They seem to be saying that after the power is out, the switch still works That can't be true. I don't trust the reviews even a little bit. The sites that review it all reprinted the same press release under the "reviewer"s byline, and the explanations in Amazon reviews sound bogus. "Q: I unplugged the lamp and moved it to another room and it didn't work. A: If you unplug the lamp it's no longer grounded." Bitch, when's the last time you saw a grounded plug on a lamp? -- Drew
Post #425,409 by boxley 9/8/18 9:36:28 PM 9/8/18 9:36:28 PM Reply	absolute crap, if its got a built in battery it doesnt need to be plugged in if you put it in a lamp it can probably sense resistance to the switch. If the power is out and it is plugged in and the switch is on there will be a measurable difference in the resistance from the bulb and the socket "Science is the belief in the ignorance of the experts" – Richard Feynman
Post #425,410 by drook 9/8/18 9:42:34 PM 9/8/18 9:42:34 PM Reply	So it's plausible it can tell the difference between turned off and power out? -- Drew
Post #425,411 by boxley 9/8/18 9:53:28 PM 9/8/18 9:53:28 PM Reply	Re: So it's plausible it can tell the difference between turned off and power out? since I answered off the top of my head I thought I should check a few things https://www.quora.com/How-do-I-find-the-electrical-resistance-between-the-two-leads-of-my-110-volt-wall-outlet-at-home If you have a doubt about the wiring being faulty or something and hence you want to measure the resistance then. first COMPLETELY DISCONNECT ALL SOURCE SUPPLY AND FULLY ISOLATE THE ENTIRE HOUSE WIRING, BOTH LIVE AND NEUTRAL. After that you could find the Resistance between any points in the dead wiring using a multimeter. The resistance in this case between the two leads of the wall socket should be very high. P.S. After the changed question details about resistance value of the source right up to generator / transformer. YES you can find out out that resistance but for that you will have to ask the power supply company to shut down the power supply to the nearest transformer before your house then you may use a multimeter. You can not directly do it with the supply on. You can not go beyond the nearest transformer because beyond that the supply is isolated. maybe a real electrical engineer can give a better answer. Alex? Others? "Science is the belief in the ignorance of the experts" – Richard Feynman
Post #425,414 by scoenye 9/9/18 12:10:03 PM 9/9/18 12:10:03 PM Reply	From those Amazon comments One reported it comes on if you short the base and the center contact. Another liked the fact that it does not come on if the power fails but it was already switched off. So, best guess: when the power goes out, there is no actual break in the circuit. There is a closed loop to the nearest transformer. The tip and ring of the bulb can still "see" each other. If that condition holds, but no line voltage is detected => bulb comes on. Flip the switch => tip and ring lose contact => bulb stays off. Well, rarely. Unless it comes with a side order of fried squirrel because someone didn't bury the line between the pole and the house properly...
Post #425,426 by Another Scott 9/11/18 8:04:38 AM 9/11/18 11:04:07 AM Reply	"No longer available" Metals are (to first order) "equi-potentials". It doesn't matter, to first order, where you measure the voltage drop between any place ~~and~~ on a metal and ground. So a simple bulb isn't going to know the difference between a switch being off in the lamp or the power being off at the circuit breaker. So, without some other voltage sense somewhere, it's not going to work as a battery backup light unless the switch between the bulb and the power is on. We have emergency flashlights at work that are plugged into 120V outlets. When the power is on, the flashlights are off. When the outlet loses power, the flashlights come on. (You can also remove the flashlights and turn them off.) I assume these bulbs work the same way, but it's hard to think of a use-case that matches using them in a lamp at home. Unless it has, say, a very sensitive Hall Effect sensor (to sense the magnetic fields from nearby AC power lines) or something similar. It does say it has some built-in intelligence, so maybe that's it. Since it doesn't seem to be available any more, at least not at B&H, perhaps its a moot point. :-) Cheers, Scott. Edited by Another Scott Sept. 11, 2018, 11:04:07 AM EDT Expand All History

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