| Oksana | Hmm... Does Nokia N900/Maemo 5 Remantle have something like "Wake On LAN"? So that when one N900 says "low battery", it also emits "wake up" signal to another (powered down) Nokia N900, and once it wakes up, transfers/syncs all the stuff changed since last sync (contacts, SMS/IMs/calls, calendar | 04:50 |
|---|---|---|
| Oksana | events, web-browsing history, email/SMS/IM drafts, photographs/audio/videos)... | 04:50 |
| Oksana | And once both devices are in sync, the "low battery" device shuts down and the other one takes over the role of "everyday device", allowing user to seamlessly continue doing whatever user was doing, without having to interrupt for "change of battery" or "plug this device into a charger"? | 04:51 |
| Oksana | Granted, all this complication is unnecessary when it is possible to swap batteries for device while it is switched on. | 04:52 |
| r00t|home | Oksana: battery swap while running is possible, but rather fragile... it's been documented by somebody, i tried it | 05:12 |
| r00t|home | Oksana: syncing the whole device state is a fun idea... but it seems a bad idea to sync all at once, especially when low on battery... i'd guess continously syncing would be more useful... and probably easiest done by offloading everything to "the cloud"... :\ | 05:17 |
| Oksana | Or most of the data to be synchronised would be written down to memory card, and once one N900 is shut down, the memory card would go to another N900 (with full battery) | 05:46 |
| Oksana | Along with SIM card ^ In short, sounds troublesome | 05:47 |
| Oksana | "Cloud" is not a reliable concept, especially when cellular data is not only limited (and going over the limit is expensive), but also unavailable (say, intercity/interstate train - cellular reception isn't available everywhere) | 05:49 |
| Maxdamantus | Could probably just implement it using uswsusp, where you write the result over the network instead of to a file/partition. | 06:06 |
| Maxdamantus | (though that involves writing and reading up to the size of memory + swap over the network) | 06:07 |
| Maxdamantus | Well, need to somehow keep MMC/SD/NAND in sync too. | 06:08 |
| Maxdamantus | Yeah, what you want is pretty much just a dumb cloud device.e | 06:08 |
| sparre | Why not just carry a USB powerbank instead of an extra N900? | 06:31 |
| sparre | You have to find one that is wired correctly though. The one I bought for my wife doesn't work with my N900. | 06:32 |
| sparre | Apparently some USB ports and powerbanks are wired in such a way that the N900 can't get power from them. The "charging" ports on my Lenovo docking station are one example (but then I use the ordinary ports for charging). | 06:35 |
| KotCzarny | i've recently bought cheapo powerbank | 06:38 |
| KotCzarny | n900 had no trouble charging from it | 06:38 |
| KotCzarny | maybe i was just lucky | 06:38 |
| KotCzarny | it's half the size of n900, yet has ~4Ah@5V, which means it could charge the n900 4-6 times | 06:40 |
| KotCzarny | on the label it's written 5000mAh, but charge meter showed 4Ah | 06:40 |
| KotCzarny | what is cool is that i was expecting 1/4 of that for the price | 06:41 |
| sparre | KotCzarny: I may have been unlucky. I should try with some other powerbanks. | 06:52 |
| Maxdamantus | I'm guessing the issue would just be the lack of a bridge between D+/D-, which can probably be solved easily. | 07:18 |
| Maxdamantus | (if you're able to open it, you could probably just solder the pins together, or tape some aluminium foil over them if you aren't able to solder) | 07:19 |
| Maxdamantus | otherwise could just modify a cable (won't be usable as a data cable anymore). | 07:20 |
| Hurrian | a bit off topic, but I swapped fans on my UPS for slower, quieter models, and now it's throwing a fan fault thanks to probably a current sensing circuit. | 14:03 |
| Hurrian | how would I go around adding dummy current load to the fans in the laziest way possible? | 14:04 |
| KotCzarny | resistor in parallel? | 14:05 |
| Hurrian | ah right, didn't think of that | 14:14 |
| Hurrian | gonna need 2x 2W resistors :o | 14:15 |
| KotCzarny | or just add some nice blinkenlichts | 14:15 |
| KotCzarny | you can also add some SBC to use that power for something useful instead of just heat | 14:15 |
| KotCzarny | allwinner a20/a64/h3/h5 draw 0.5-2W in idle/under load | 14:16 |
| Vajb | put enough fans in series so voltage will drop :p | 14:16 |
| KotCzarny | s/0.5-2W/0.5-2A | 14:16 |
| KotCzarny | he doesnt want to drop voltage | 14:17 |
| KotCzarny | :) | 14:17 |
| Hurrian | Needs to take in 12V though - considering just replacing the current sense resistor with a normal resistor at fixed value but that's harder | 14:17 |
| Maxdamantus | increased current = decreased voltage | 14:17 |
| Hurrian | Not sure whats causing my UPS to switch to bypass mode though, theoretically even with a fan fault it should keep running | 14:18 |
| Hurrian | Suspecting increased heat thanks to the slower fans, so gonna keep it in front of the A/C for the night | 14:18 |
| KotCzarny | put a thermo probe and log? | 14:19 |
| Hurrian | if it's that, then I'll definitely just add a normal 120mm PC fan in it to keep the NTC thermistor happy :p | 14:19 |
| Hurrian | KotCzarny: doesn't really matter how many ohms resistor I use right? just that I get the right wattage to increase amp draw? | 14:39 |
| KotCzarny | i'm not an expert in electronics, but watts on resistor is tied to resistance | 14:41 |
| KotCzarny | so yeah | 14:41 |
| KotCzarny | p=i*i*r | 14:41 |
| KotCzarny | still, get an answer from someone skilled in electronics to make sure | 14:45 |
| Maxdamantus | The wattage rating is the maximum power dissipation for the resistor. | 14:46 |
| Maxdamantus | The power it draws still depends on the supplied voltage and the actual resistance. You're just not meant to use a voltage high enough that it uses more than that power rating, otherwise it will overheat. | 14:48 |
| Maxdamantus | (disclaimer: I'm also not skilled in electronics) | 14:48 |
| Maxdamantus | as KotCzarny said, P = I*I*R, or P = V*V*R, which should be simple enough to use when putting the resistors in parallel. | 14:53 |
| inz | P=V*V/R | 14:55 |
| Maxdamantus | er, yes, oops. | 14:55 |
| inz | High school pays off, wohoo. | 14:57 |
| bencoh | haha :) | 14:57 |
| Maxdamantus | so to dissipate 4 W over say 12 V, you need (V^2)/P = (12 V)^2/(4 W) = 36 Ohm of resistance. | 15:00 |
| Maxdamantus | (and the resistor needs to be rated at at least 4 W) | 15:00 |
| Maxdamantus | dunno what margins are like .. never played with power resistors | 15:01 |
| r00t|home | Hurrian: it's more likely the rpm sensor... nobody would monitor the current of a fan (that i can think of) | 17:01 |
| r00t|home | Hurrian: i had that with a dell server PSU... i ended up connecting the cpu fan's rpm sensor output to the power supply's fan connector's rpm input | 17:01 |
| Hurrian | thanks guys, got it to work - tried a huge 5W resistor and it stopped the fan from spinning, then tried a 1/2 watt resistor and it spun right up and cleared the fan error :D | 18:43 |
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