How to measure voltage on an android

Discussion in 'General Electronics Chat' started by Pavle, Dec 9, 2015.

  1. Pavle

    Thread Starter Member

    Dec 6, 2015
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    How to measure voltage at micro usb port on android with multimeter???
     
  2. #12

    Expert

    Nov 30, 2010
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    Connect the black (-) lead of the meter to, "ground" or, "common". Connect the red lead of the meter to the point you want to measure. Something in the range of zero to 5 volts is to be expected.
     
  3. Pavle

    Thread Starter Member

    Dec 6, 2015
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    I connected black wire to the ground and red wire to red wire but is not showing anything on display.
     
  4. #12

    Expert

    Nov 30, 2010
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    I don't know the color codes of an Android or a USB connector. Perhaps some other person could help.
     
  5. Lestraveled

    Well-Known Member

    May 19, 2014
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    The connection to a Android in an input. Plus +5 volts should not be present. You might get some voltage on the data pins if there are pull-up resistors.
     
  6. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Which end of it? The charger or the phone?
    A charger should give 5V between the outermost terminals IIRC.
    A phone could be giving out 5V, but it just as well might not. That depends on the hardware of the phone and if it supports USB OTG.
     
  7. Pavle

    Thread Starter Member

    Dec 6, 2015
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    I want to know how much voltage is android giving out???
     
  8. Lestraveled

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    That would be a little difficult since the battery voltage in cell phones is about 3.6 volts.
     
  9. Pavle

    Thread Starter Member

    Dec 6, 2015
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    How can I do that???
     
  10. Lestraveled

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    I do not think a cell phone will output voltage on the micro USB connector. It is designed to receive 5 volts to charge the battery.
     
    DerStrom8 likes this.
  11. Pavle

    Thread Starter Member

    Dec 6, 2015
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    My S3 Neo supports USB OTG but it cannot provide enough voltage to otg devices.
     
  12. Pavle

    Thread Starter Member

    Dec 6, 2015
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    How to fix that???
     
  13. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    The USB OTG spec says 4.4V to 5.25V, so the phone obviously needs to do a boost conversion from the battery voltage. Not too difficult with modern minitaturization, but still a hassle, which is why not too many devices have this.
     
  14. Pavle

    Thread Starter Member

    Dec 6, 2015
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    How to boost conversion from battery voltage???
     
  15. kubeek

    AAC Fanatic!

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  16. Lestraveled

    Well-Known Member

    May 19, 2014
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    From https://en.wikipedia.org/wiki/USB_On-The-Go

    It does so by periodically measuring the capacitance on the USB port to determine whether there is another device attached, a dangling cable, or no cable. When a large enough change in capacitance is detected to indicate device attachment, an A-device will provide power to the USB bus and look for device connection.

    It will not provide power until it senses another device.
     
  17. Pavle

    Thread Starter Member

    Dec 6, 2015
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    Is there a way to power otg device without y cable???
     
  18. kubeek

    AAC Fanatic!

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    no, unless you have an OTG host deivce.
     
  19. Pavle

    Thread Starter Member

    Dec 6, 2015
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    I cut android usb cable and connected red wire with red wire,black wire with black wire and plugged in usb port to pc and micro usb port to android and multimeter says 4.76 volts.
     
  20. Lestraveled

    Well-Known Member

    May 19, 2014
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    I am pretty sure that the voltage is coming from the PC. What happens when you open the red wire. Is there voltage on the android side?
     
    DerStrom8 likes this.
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