I understand the basic concept of wireless power transfer.
I wanted to make some wireless LEDs (Similar to this concept) and was trying to figure out the minimum component count I required in order to make the boards as small as possible.
I'm assuming that the inductive charging used in phones utilises some sort of full wave rectification and a voltage regulator inside the phone in order to feed a fixed voltage DC level into the battery. (Please correct me if this is wrong)
Now the circuit I was thinking is as shown below:
So on the transmitter so I'd use a micro to create a square wave at a similar resonant frequency to the coil.
On the receiver side I'd use a single diode for some half wave rectification and a capacitor to smooth it out and use it to power the LED. I'm hoping that if I use a coil with a resonant frequency of 10-20kHz then this will be fast enough to overcome the capacitor discharging too much and will give a roughly stable DC-ish voltage.
Or can I go more simple than this and just have a resistor and an LED without worrying about any rectification? As long as the reverse voltage across the LED isn't too high during the negative half cycle.
I assume the LED would be dimmer overall as it's essentially like running an LED at 50% duty cycle with PWM but aside from that is there any other problems that might occur?
The other product on the market seems to use only 4 components from what I can see (coil, 2 caps and an LED) but can't quite figure out how it would be possible if anyone has any insights?