Wireless Charger

Discussion in 'The Projects Forum' started by mamakuxa, Oct 14, 2015.

  1. mamakuxa

    Thread Starter New Member

    Oct 5, 2015
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    Hello,

    I am currently working on a wireless charger project, where I am to use a 120/24V transformer as a power source to create a wireless charger module for a regular 5V/<1A USB output plug. I have attached my transmitter circuit below. I am using a colpitts oscillator using a pair of 0.1uF caps and a 100uH inductor to produce a 73 kHz frequency. I am also getting a 11.4Vpp output. I have a couple questions if anyone can help.

    1) Where would I connect the other end of my transmitter coil? I get a output from the oscillator circuit but I dont know where to connect the other end to.

    2) Is 11.4Vpp enough to power my charger at the transmitter side? It is going through a bridge rectifier to a 5V regulator to a female usb plug.

    3) Anyone have a suggestion to improve this circuit? I heard a MOSFET would help in place of the BJT but how would taht affect my circuit?

    Thank you for the help in advance! I am working solo on this and any help would be appreciated
     
  2. ronv

    AAC Fanatic!

    Nov 12, 2008
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  3. mamakuxa

    Thread Starter New Member

    Oct 5, 2015
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    Thank you, @ronv. This helped a lot with the science background of it. I am still curious about what I can fix with my current circuit. I unfortunately, dont have enough time to completely rebuild my circuit right now. I have made some changes using the write up! Thanks!
     
  4. ronv

    AAC Fanatic!

    Nov 12, 2008
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    One of the most important things is that the transmitter resonant frequency be the same as the circuit driving it. So the transmitter needs to be a series resonant circuit at the same frequency as your oscillator. I don't think you can drive it directly with your oscillator.
    The bad news is you need to start over. :(
     
  5. mamakuxa

    Thread Starter New Member

    Oct 5, 2015
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    Can you elaborate of that statement? :/ I am assuming that the components R,L and C must have a special correlation like the "Q" factor. I read into the problem and seem I have a lot of work to do to fix these components. However, would it still be possible, after fixing these components, to drive a wireless transmitter with this "colpitts oscillator"

    btw, thank you so much for your continuous help.
     
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