Made a Charger but mobile won't draw any current.

Discussion in 'General Electronics Chat' started by Qasim Raza, Aug 6, 2015.

  1. Qasim Raza

    Thread Starter New Member

    Aug 6, 2015
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    I made a charger using 7805 and used a PNP to increase current. Output side was connected as shown in figure.
    7N84m.png
    But when i connect it to mobile, mobile shows that it is charging and drawing 1200mAh
    Screenshot_2015-08-06-09-56-16.png
    But battery goes on decreasing and when i connected a multimeter, it showed that no current is going into the phone.

    Then i removed phone and connected a 3.3 ohm 5 Watt resistor, circuit was perfectly working. Can anyone suggest a solution?
     
  2. Jampo

    New Member

    Aug 6, 2015
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    I'm not very clued up on this, but I would like to ask a few questions. How well does your circuit's characteristics, i.e. volts, ampere, match that of the branded charger? Does the phone charge through a branded charger? (Has the phone been damaged?) How can it be that there is no current going into the phone if the reporting software tells you on the screen there is something going on?

    Maybe there is (most likely) some sort of protection circuitry in place in the phone. The charging circuitry may be separated from the input to the reporting software. These systems may run in parallel and not in series.

    Then, something seen on sspence's Green-Trust site - knowledge new to me - your charging voltage has to be higher than the battery's stored voltage.
     
  3. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    How did you connect the multimeter to test current? When measuring amps you must put the meter in series with it, meaning you need to break the positive wire and put the meter between the two halves.

    In order to get the phone to charge, you really shouldn't be using it while plugged in. Otherwise you may be draining it faster than you're charging.
     
  4. TheButtonThief

    Active Member

    Feb 26, 2011
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    What's your calculated wattage of the charger and what's the mAh value on the phone's battery?
     
  5. Qasim Raza

    Thread Starter New Member

    Aug 6, 2015
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    Voltage was 5.07 v as measure by multimeter.
    I broke the charging cable and soldered it petmanently to the ckt as i didnt have the female USB port. So current measurement was not a problem because I only had to melt the soldering and put ammeter.
    My circuit was efficient because with 3.3 ohm resistor connected, 1.4 amps was going through thr resistor and 4.98 vilts were accross the resistor. Good load regulation.
    Yeah might be some kind of protection.
    By the way I am try to charge my Note 3, phone is good because it is charging whith any other chargers.
     
  6. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
    1,190
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    You need to post the whole circuit here not have . Also 2 lines are power and the others are data .. I could be wrong here but I believe that apple products are the only one that uses the resistor network to get a higher charging rate or even charge.. Most times I just run to my local flea market for chargers for a buck a piece.
     
  7. Qasim Raza

    Thread Starter New Member

    Aug 6, 2015
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    5V 5A power supply.jpg
    I used this circuit
     
  8. Metalfan1185

    Active Member

    Sep 12, 2008
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    Some USB devices use a pulldown/pullup resistor on a separate pin to "enable" charging (most of the time its molded into the smaller connector on the charge/data cable. I have done something similar to what you are trying to accomplish here and I found that i needed to pull one of the pins low. I dont remember which one it was a long time ago. Are there any other pins in the connector of the phone besides the outside shield, +5, GND, d+, and d-?
     
  9. Qasim Raza

    Thread Starter New Member

    Aug 6, 2015
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    Yeah a pin that tells whether it OTG cable or Normal USB cable. But it is not connected during charging process.
     
  10. Veracohr

    Well-Known Member

    Jan 3, 2011
    550
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    I don't have any insight into the current issue but the 7805 has a 2V dropout voltage. To get regulated 5V out you need at least 7V in.
     
  11. Qasim Raza

    Thread Starter New Member

    Aug 6, 2015
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    No drop out sir. Perfect 5.07 Volts.
     
  12. Qasim Raza

    Thread Starter New Member

    Aug 6, 2015
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    I'm going to change data pin connections to see what happens.
     
  13. KLillie

    Member

    May 31, 2014
    126
    14
    What input voltage are you using on your voltage regulator circuit? And did you change data pin connections?
     
  14. bertus

    Administrator

    Apr 5, 2008
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