| 00:03.05 | *** join/#qi-hardware dos1 (~dos1@unaffiliated/dos1) |
| 00:23.35 | wolfspraul | wpwrak: hmm. is it possible that that is just this greylisting stuff? |
| 00:24.01 | wolfspraul | where does this error msg come from - did you get a final "cannot be delivered" back into your mail client? |
| 00:25.11 | wpwrak | so far it's just trying to connect. is it MTA running ? on turandot, telnet localhost 25 -> telnet: Unable to connect to remote host: Connection refused |
| 00:26.02 | wpwrak | and the mail hasn't timed out yet on my side. don't remember what timeout i set. probably something relatively large |
| 00:26.37 | wpwrak | yeah, 5 days :) |
| 00:26.57 | wpwrak | but it'll start complaining after 4 hours |
| 00:39.30 | *** join/#qi-hardware sulky (~sulky@148.163.189.33) |
| 00:52.17 | DocScrutinizer05 | seems there's really stormy weather in the internets, eh? |
| 00:53.18 | wpwrak | looks more like some system upgrade at qi-hw, and the usual fallout such things produce |
| 01:08.23 | *** join/#qi-hardware mth (nzjmvmqg@88.159.34.112) |
| 01:15.27 | wpwrak | hmm, i wonder if AAA + diode + polyfuse would work for battery reversal protection |
| 01:16.22 | wpwrak | (as alternative to an "ideal diode") |
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| 01:21.50 | wpwrak | the sub-question there is what the damage mechanism is for battery reversal. i.e., what sort of current has to flow through the reversed AAA battery to actually do damage to the circuit |
| 01:22.31 | wpwrak | but i suspect that relatively little may be sufficient, i.e., a few hundred mA |
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| 01:52.24 | wpwrak | wolfspraul: thanks ! :) |
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| 02:52.33 | whitequark | wpwrak: there are ideal diodes. |
| 02:52.51 | whitequark | well, "diodes" with zero drop. they're available. it's actually a fet in a diode package |
| 03:08.45 | wpwrak | got an example ? |
| 03:09.21 | wpwrak | looking for "ideal diodes" i found some parts, but usually stuff that's far out of the range we'd need here |
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| 03:33.36 | whitequark | wpwrak: hm |
| 03:33.41 | whitequark | so there's this 55mV Schottky https://www.digikey.com/product-detail/en/fairchild-semiconductor/SS14FP/SS14FPCT-ND/5892130 |
| 03:34.25 | whitequark | I can't find the exact device I was looking for yet, but does it even matter for your application? |
| 03:39.01 | wpwrak | you mean the 0.55 V = 55 mV type ? :) |
| 03:39.35 | wpwrak | the golden rule still applies: if it's too goo to be true then it probably isn't ;-) |
| 03:39.47 | wpwrak | or, in the case of digi-key: then it's probably a typo :) |
| 03:40.07 | whitequark | ah right, it's a typo |
| 03:40.12 | whitequark | anyway, this is what I was talking about: https://www.maximintegrated.com/en/app-notes/index.mvp/id/636 |
| 03:48.22 | wpwrak | here is a "smart diode". alas, expensive (and designed for higher-current applications): https://www.digikey.com/product-detail/en/texas-instruments/SM74611KTTR/296-35688-1-ND/3911155 |
| 03:49.29 | wpwrak | ti's data sheet is from 2012. so maybe around 2030, when the patents expire, we'll see more such smart diodes ... |
| 03:50.29 | wpwrak | the maxim circuit with boost converter is interesting. haven't thought of that. |
| 03:51.36 | wpwrak | the FET circuits all have the problem of low voltage. it's hard to find FETs that are happy to admit ~ 1 A with a low drop and Vgs <= 1 V |
| 03:52.53 | wpwrak | a radically different approach would be to block this mechanically |
| 03:54.35 | wpwrak | not sure how well that would work, though. the "nipple" of an AAA cell is supposed to stick out by >= 0.8 mm. so an obstacle of about 0.5 mm around the contact should work. however, i don't remember ever seeing such an arrangement in real life. there may be a reason for it. |
| 04:18.48 | whitequark | yeah, the voltage is troubling |
| 04:22.21 | whitequark | oh, I remember now the proper name for the device I was looking for |
| 04:22.42 | whitequark | "MOS Rectifier" |
| 04:23.46 | whitequark | they do have lower Vf than regular Schottky diodes but I think not lower enough |
| 04:24.03 | whitequark | http://www.ttiinc.com/object/Vishay-45V-Trench-MOS-Barrier-Schottky-Rectifier |
| 04:24.10 | whitequark | 0.28V@5A apparently |
| 04:26.37 | whitequark | but those are unavailable... and I've definitely seen those in production |
| 04:28.56 | *** join/#qi-hardware DocScrutinizer05 (~saturn@openmoko/engineers/joerg) |
| 04:30.13 | whitequark | AHA! found it. |
| 04:30.15 | whitequark | wpwrak: http://www.ti.com/lit/ds/symlink/sm74611.pdf |
| 04:30.20 | whitequark | 26 mV at 8 A |
| 04:30.23 | whitequark | and that's not a typo. |
| 04:30.41 | wpwrak | see above :) |
| 04:30.51 | whitequark | nope |
| 04:30.53 | whitequark | read the datasheet. |
| 04:31.02 | whitequark | oh |
| 04:31.06 | wpwrak | ;-) |
| 04:31.14 | whitequark | oh, you found that device |
| 04:31.14 | whitequark | yeah |
| 04:31.42 | whitequark | I was under impression that there were more of them |
| 04:31.49 | whitequark | but this is exactly the thing I had in mind. |
| 04:34.20 | whitequark | the maxim circuit is basically the same thing as that diode, except discrete |
| 04:55.48 | whitequark | wpwrak: how about this? https://www.fairchildsemi.com/datasheets/FD/FDN327N.pdf |
| 04:55.57 | whitequark | Vgs=1.8 |
| 04:56.09 | whitequark | Rds(on)=120m, meaning Vf=120mV |
| 04:56.23 | whitequark | at your target 1A |
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| 05:29.16 | wpwrak | needs boosting. Vgs(th) is too high |
| 05:30.04 | wpwrak | after all, that little battery can only cough out 1.5 V when fresh, and with use, it gets worse |
| 05:31.36 | wpwrak | these are the results of the little search i did: https://defuse.ca/b/pYH84uqSKqz33KLH2YnlPT |
| 05:31.50 | wpwrak | i found no p-FET that looked truly convincing |
| 05:32.00 | wpwrak | i found two n-FETs that may be okay |
| 05:34.06 | whitequark | oh right, you have an AAA battery, not li-ion |
| 05:34.34 | wpwrak | but i wonder if there may be an easier solution. that variant with providing the gate voltage from the boost converter looks interesting. not quite sure if it would actually work, though. the path of components that are borderline operational gets fairly long. |
| 05:34.57 | wpwrak | yup. if i had 3.7+ V to burn, there would be no worry at all ;-) |
| 05:41.26 | wpwrak | the big concern is to avoid choking the battery too early. e.g., when current demand is high, battery voltage drops in the battery and then again at the FET. the resulting lower boost Vin makes it draw even more current. worse, since that reduced voltage is also Vgs, the FET becomes more resistive, further increasing drop and current demand |
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| 06:53.00 | eintopf | mhh, I like smartphones which getting hot when I turn on GPS. Then I have something to heat me up at the bus station when its winter |
| 07:00.43 | kyak | it get hot because of GR effects. You phone travels in time and space, and it is quite hot there |
| 07:01.16 | kyak | while waiting for a bus, don't forget what's your phone is going through |
| 07:01.27 | *** join/#qi-hardware sandeepkr (~sandeep@111.235.64.4) |
| 07:21.58 | xiangfu | wpwrak: Hi |
| 07:23.08 | xiangfu | wpwrak: we got 15 N900. one of them is very bad. the others looks like ok. but all used devices. vc.cheng@can.... should be send one email to you. with pictures. |
| 07:23.16 | xiangfu | wpwrak: let me know what should I do next? |
| 07:23.30 | xiangfu | but it is not easy to get 200 of them. I buy them slowly... |
| 08:47.41 | wpwrak | are all 15 from the same source ? and have they been cleaned properly, i.e., are they of similar quality as the refurbished we looked at some months ago ? or are they worse ? |
| 08:48.55 | wpwrak | (not easy) the messier the sourcing, the greater the glory ;-) |
| 10:05.12 | *** join/#qi-hardware pcercuei (~paul@137.71.226.54) |
| 10:06.29 | whitequark | wpwrak: the boost circuit really shouldn't draw any current |
| 10:06.44 | whitequark | maybe microamps. it has to run the charge pump once, and afterwards its job is done |
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| 12:04.49 | eintopf | it's not a good idea to glue your usb hubs on your table with a velcro fastener powerband... |
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| 18:42.54 | *** join/#qi-hardware infobot (ibot@rikers.org) |
| 18:42.55 | *** topic/#qi-hardware is Copyleft hardware - http://qi-hardware.com | hardware hackers join here to discuss Ben NanoNote, atben/atusb 802.15.4 wireless, anelok and other community driven hw projects | public logging at http://en.qi-hardware.com/irclogs and http://irclog.whitequark.org/qi-hardware |
| 18:42.55 | *** mode/#qi-hardware [+v infobot] by ChanServ |
| 18:47.11 | wpwrak | yes, i thought of that, too. the boost converter i'm considering has a "battery good" signal. i think it may be used for something like this, but need to check some more. |
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| 19:05.25 | DocScrutinizer05 | wpwrak: (mech reversal block) http://maemo.cloud-7.de/share-service/DSCF1916.JPG http://maemo.cloud-7.de/share-service/DSCF1917.JPG AA but the principle is the same |
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| 19:12.26 | DocScrutinizer05 | http://wstaw.org/m/2016/03/23/DSCF1914.JPG halfassed implementation, actually a fail |
| 19:19.44 | *** join/#qi-hardware mth_ (aaawcdhg@88.159.34.112) |
| 19:23.36 | wpwrak | kewl. so it does exist in real life. no FET or polyfuse needed then :) |
| 19:24.06 | wpwrak | the less gunk in the power path, the better |
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| 20:36.11 | wpwrak | hmm. too good to be true ? https://www.kickstarter.com/projects/olo3d/olo-the-first-ever-smartphone-3d-printer |
| 20:52.11 | mth | the campaign period does include April 1st |
| 20:52.50 | mth | if it's a light-sensitive resin, shouldn't it be kept in opaque bottles? |
| 20:56.15 | wpwrak | mth: yes, at heise.de they have a pretty long list of doubts: http://www.heise.de/newsticker/meldung/Olo-3D-Druck-mit-dem-Licht-aus-dem-Smartphone-Display-3149561.html |
| 20:56.18 | wpwrak | puzzling |
| 21:14.10 | mth | here is a company that claim to use daylight resins as well: http://www.photocentric3d.com/ |
| 21:14.19 | mth | all their bottles are black though |
| 21:15.12 | mth | maybe the tech is real but the video is faked since the kickstarter project has no working product yet? |
| 21:20.02 | mth | (which would violate kickstarter rules for hardware projects) |
| 21:29.12 | mth | hmm, in their demo video they seem to fill the tank from a black bottle |
| 21:30.41 | mth | so the bottles shown in the main video are probably not actual resin |
| 21:31.09 | mth | also, if it takes 4 hours to print a small object, is it actually a good idea to use a phone as the screen? |
| 21:31.26 | mth | well, if you have an old smartphone around that you no longer use as a phone, I guess |
| 22:34.25 | wpwrak | if the thing works, it would still be cheap if you add the cost of a new smartphone :) |
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