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Showing 1 of 136 conversations about:
nickaa827
289
Apr 16, 2017
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100 mA is quite bad for power output on the USB ports. Guys, keep in mind that most phones charge adequately at 10 times that.
Apr 16, 2017
TipsyMacScotchslurpen
379
Apr 17, 2017
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nickaa827While I wouldn't buy this keyboard for other reasons, most of the things I would plug into the USB ports on my keyboard probably don't draw more than 100mA: mouse, thumb drives, card readers, mooltipass (a secure offline password storage device), and maybe a bluetooth dongle. I would use a usb extension cable or powered USB hub if I wanted to plug in an external HDD/SSD, headphone amp/DAC, WiFi card, a device that needs charging, or something that only requires power (like a USB-powered LED desk light).
Apr 17, 2017
nickaa827
289
Apr 19, 2017
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TipsyMacScotchslurpenYou'd be surprised. I tried to plug in my flash drive to my old Mac keyboard USB port and my computer gave me an error message saying it couldn't read the flash drive because of the low power output.
Apr 19, 2017
TipsyMacScotchslurpen
379
Apr 19, 2017
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nickaa827Out of curiosity, was it a high-speed drive of some sort? Like something that can support read speeds over 100MB/s?
Some of the recent USB3 thumb drives are almost solid state drives with a USB3 controller instead of SATA3 one. I have a Sandisk Extreme flash drive that can pull something like 130MB/s, but I've never tried to plug it into my old Corsair K95. I might have to dig it out and see what happens.
P.S. - I found the specs on my Mooltipass, and it claims it needs 5V 0.5A, so it may not work on 100mA.
Apr 19, 2017
nickaa827
289
Apr 19, 2017
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Apr 19, 2017
TipsyMacScotchslurpen
379
Apr 19, 2017
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nickaa827Haha, looking at the amazon questions for that drive one person claims that the drive gets ridiculously hot if a transfer takes more than 15 seconds. It probanly takes more than 100mA to heat up a drive that fast. ;)
It is interesting, though, that a drive plugged into a USB2 port would need the juice if it is limited to ~35-50MB/s (for practical purposes... technically the max transfer rate would be 60MB/s, but you have USB protocol overhead that limits actual data transfer) by USB2.0's max speed. USB3.0 devices are allowed to pull 900mA, so some of the high speed devices use multiple flash chips and a striping controller that reads/saves a chunk of the data to each chip simultaneously to reach those high speeds (similar to several drives in a RAID0 array). Because of this it is effectively several USB2.0 drives all plugged into one USB port.
Apr 19, 2017
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