Experimental wireless lamps at 130 kHz

These leds are powerd by a strong magnetic field in the LW-band. The fiedstrength is below the limit for inductive systems.
In the air-cored coils of 20 mm a power of 100 mW is available within a distance of 100 mm.

With the high-Q ferrite rods (5*50 mm) this power can be drawn from a larger distance. Some of the air-coils are indirectly powered by the ferrite-coils.

The transmit-coil below is tuned at the working frequency and driven by a high efficiency RF-generator which consumes only 3 W from 12 V.

 

Wireless lamps at 13,56 MHz

At 13,56 MHz a much higher sensitivity and Q-factor is attainable in the receive-coils, so less copper and a much lower fieldstrength than at 130 kHz are needed.

These lamps below demonstrate the power absorption with single wire loops (blue LED's) and with small 8-turm 20mm loops (green LED's).

The magnetic field is generated with only 0,5 Amps in an 8-loop of single thin wire below the table. The transmitter feeds the 0,5 mm wire with 1 Watt, resulting is a local magnetic fieldstrength of 600mA/m, and <0,02 mA/m at 10 meters, far below the limits (EN300330: 0,125 mA/m at 10 meters).

The higher frequency of 13,56 MHz makes this system more energy-efficient than the ferrite-coils at 130 kHz.

At the table-surface a power of 100 mW is available, at a height of 50 cm this drops to 10 mW.