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Kinetic Phone Charger

Discussion in 'General Electronics Discussion' started by James Williams, Mar 4, 2016.

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  1. James Williams

    James Williams

    Mar 4, 2016
    I'm a student who's building a kinetic phone charger for my project in engineering.

    The problem is that when I test the kinetic device directly with the multimeter I get between 10 - 40 v AC. The second I solder the device to the PCB and test it at that point, I'm not even getting 1v AC. This is before any resistance can effect anything as I'm testing it at the same point as before, only connected to the PCB. The component I'm soldering it on to is a rectifier, so converting AC to DC but again I'm not testing it after its converted, I'm testing it before I am.

    I have scrapped off the enamel on the copper wirer and soldered it. Still same problem. Then soldered wirers onto the copper and tested it and it works, but again when I solder it onto the PCB I get below 1v AC.

    Another thing I tried was soldering it to a 50v max voltage, three pin connector and tested it before, getting again 10-40 volts. But the second I connect the other connecter, I have the same problem as with soldering it onto the PCB.

    If anyone has any ideas or can see the stupid thing that I've done, please help.
  2. dorke


    Jun 20, 2015
    Welcome to EP.
    Sound like you have soldered a diode directly across the output of the device.
    A clear photo may help.
  3. BobK


    Jan 5, 2010
    Agree with Dorke, but, even with the circuit corrected, do expect a drop in voltage as soon as you connect a load.

  4. Alec_t


    Jul 7, 2015
    Exactly what is your AC generator? What is its impedance?
  5. James Williams

    James Williams

    Mar 4, 2016
    Thank you
    This is the device soldered onto the PCB (wide view) and the device directly soldered onto the PCB to the rectifier. After the rectifier you have some super capacitors, then voltage regulator and a small capacitor. Then a set of resistors for the data connectors for the USB connection.

    Little update, replaced the rectifier with a new one and soldered it on, but not the DC pins. I did get a 10-30 AC voltage from the soldering points (not like before). But then as soon as i soldered the two DC connections i get the problem again, i get between 0-1 volts. So must be the PCB or other components??

    At this moment i decided the de-solder some of the super capacitors (6.3 DC voltage) and i know that the value of them has to be greater than the voltage input and the PCB was originally made for a device making more voltage so i removed some, leaving only 6. (37.8v). But still it hardly generates anything.

    Attached Files:

  6. Bluejets


    Oct 5, 2014
    I'd say yout "generator" is not as you expect.
  7. dorke


    Jun 20, 2015
    It is most likely that the charging current of the "super caps" is large ,
    so that the "generator" is overloaded and it's voltage drop's.
    i.e your generator has very low power capabilities

    Try using a "lighter load" instead of the "caps",
    like a 5k to 10k (variable) resistor to verify this.
  8. Alec_t


    Jul 7, 2015
    If your generator is a series of piezoelectric discs then they have such a high impedance that you will get very little current out of them. Their output voltage gets attenuated dramatically by a low-impedance load. Their average output power is miniscule.
  9. AnalogKid


    Jun 10, 2015
    So the kinetic device isa moving-magnet generator? If so, then we need a schematic of the circuit.

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