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This is based on a project by Marko at 4hv,org. I laidout the PCB in Express PCB.
"The idea behind the project was to create a small tabletop demonstrator of magnetically coupled wireless power transfer, resembling a miniature version of the MIT 'witricity' device. The goal was to keep the circuit simple with easily obtainable parts, and to keep voltage and power levels low so the device is safe for handling and doesn't require special methods of cooling.
The basic idea is to feed a parallel LC tank circuit from an AC voltage source at it's resonant frequency, which allows large reactive current to circulate in the circuit while only real power is being drawn from the source. This sets up a large alternating magnetic field in the inductor, which is designed as a single conductive loop in this case.
Now, another LC tank with load attached is brought in proximity to the excited LC circuit, significant amounts of power can be transferred via weak magnetic coupling between them. This is because AC current itself in the transmitting loop is very large, and inductive reactance of the receiver loop is canceled out by the capacitor.
For a practical device, the AC voltage source had to be substituted with an appropriate oscillator, which would take feedback from the tank circuit itself and hence always drive it at it's resonant frequency.
The circuit of choice was a slightly modified royer oscillator, such as popularly used in CCFL inverters and for flyback drivers.
Input voltage was limited to 15V for safety and because the circuit tends to become unstable at higher voltages."
Folding Flex PCB Paper Cutout of Canine Scull nRF51822 Bluetooth Telemetry Implant. Wireless Power, Inertial Sensors and Dual Rosette Strain
running v1.41 (really) of VoluMaster™.
its neat to see in person, when you switch outputs (from speaker amp to headphones via the dedicated outboard phones amp) you get a whole SCRIPT of things happening!
- volume slow fades down to mute
- current amp is turned off at the power outlet via x10 wireless relay device
- new amp is turned on via x10 device in a similar way
- turn-on delay timer is started
- after delay, volume is ramped up from mute to last set value
its orchestrated perfectly. to switch devices is graceful and power efficient ;)
similar things happen when the 'sleep timer' (yes, there is one!) expires. the volume is ramped down, a message is displayed on the lcd (lol) and all amps are turned off.
note that this is JUST for development and playing with. the final version will be in a 'proper' case and with proper pc boards and no 30 year old faded-white protoboards (lol).
Simple S Gate. Ground goes to one side of thin double copper clad board. Second Parasitic plate is copper and attaches to the coil. Front tube is the copper resonating cavity it attaches to negative side of LED.LED with AV plug attaches to other side of coil.
Microchip and Powercast jointly developed the Lifetime Power® Energy Harvesting Development Kit for Wireless Sensors, which is the world’s first RF energy harvesting kit that enables battery-free, perpetually powered wireless applications. The combination of Powercast’s RF Energy Harvesting System and Microchip’s eXtreme Low Power PIC® Microcontrollers eliminates batteries in a wide range of applications. For more information, visit: www.microchip.com/RFEnergyHarvesting
Prototype wireless implantable Rosette Strain Gauge transceiver. Three Instrumentation amplifiers connected to Nordic 8051 based 2.4GHz transceiver ADC's.
Testing Integrated Circuits such as 65nm bionic eye chip require PCBs to analyze chip functions on the bench top.
Wireless Charging iPhone 4 and iPhone 3G- Wireless Charging receiver cases and charge pad, inductive charger.
Wireless Charging iPhone 4 and iPhone 3G- Wireless Charging receiver cases and charge pad, inductive charger.
External 7M3728MHz Wireless Power Transmitter. Includes 2.4GHz RF telemetry to control Class-AB coil driver and coil oscillator.
A great gadget if you already have a Nokia charging plate but want to charge devices with microUSB port...