A marvellous combination of the analog magnetic levitation technology from the 70´s and wireless energy technology from the 90´s.
A large electromagnet, constructed from old 400VA transformers, is controlled via a Class-D amplifier.
The analog control-signal originates from a set of Hall-sensors, converting the distance between the 2 magnets to a linear voltage, and controls the current in the electromagnet.
A RF- antenna-loop around the electromagnet generates a RF-magnetic field of 4W RF-power, at 6,78 MHz, supplying the rectifier in the lamp with 2 – 3 W energy.
To handle the 3 magnetic fields; from electromagnet, sense-field Hall-sensors, and RF power-field, in same area without any interference, special shielding was needed. Levitation-distance can be set and modulated between 2 and 10 cm.