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# Wireless charger

#### islam Morsy

##### Newbie

As shown in the circuit above, I am trying to do a wireless charger system by using PWM waves and LC tank logic. After completing the the transmitter circuit and it was working successfully, and I get the wave using the oscilloscope in the receiver circuit as I wanted, but the voltage at the bridge recitifier was very low, which made the output voltage of the lm7805 3.5v instead of 5v.

After experiments and research, I used the ac power supply with a AC 12v input to the bridge recitifier, and I get the correct Voltage, but when reducing the current less than 100mA, the voltage decreases to 2 or 3v. This is what happens in my circuit, but I am not really sure , and also I do not know what the solution if it was problem

So is the problem really Current as I think or there is any another problem and how can I solve?

I guess the transformer is your stand-in model for two coils close together. Coupling coefficient is a way to simulate the effect of weakening magnetic flux over a distance. How to select coupling coefficient? This is hard to answer. 99%? 90%?

Your schematic appears to provide pulsed DC through your sending coil. This allows merely 50 percent utilization of the coil. Efficiency goes up when you cause it to emanate maximum power. Therefore send bipolar AC through it. A simple self-oscillating circuit is sufficient. Start with a lesser supply voltage than 12V.

Your receiver section needs to be tuned to the exact frequency beaming from the sending coil.

Your output section consists of several components, requiring that your receiving coil produce several volts. I believe that 2 led's anti-parallel by themselves can be powered from your coil.
Say a red led needs 2VDC 10mA. That's .02 W. Suppose you feed 1W to your sending coil.The led's should illuminate if you manage to obtain just 2% efficiency.