Pulse-driven electromechanical pendulum

Description

Discover the fascination of a pendulum that never stops! This pulse-driven electromechanical pendulum keeps swinging by making up for friction losses. At the heart of the system is a Hall effect sensor (A3144) that detects the bob as it passes and drives two cascaded NPN transistors, which in turn energise a coil, producing synchronised magnetic pulses that give the pendulum the push it needs.

The flashing RGB LEDs add a cyclic light effect, creating a hypnotic visual display that runs independently of the movement. Elegant and full of technology, it makes a perfect desk ornament or collector’s piece.

Soldering required for assembly. The kit is supplied complete with assembly instructions.

Circuit diagram

The pendulum’s striking light effect in the dark

Technical specifications

• Power supply: 5 V DC regulated, about 500 mA (adjustable down to ~4.5 V).
• Pendulum: cylindrical magnet Ø11 mm × 4 mm, magnet-to-core height 8–10 mm, Plexiglas support with plastic tube.
• Operation: swinging is sustained by making up for friction losses; the coil delivers synchronised magnetic pulses that push the pendulum.
• LED: flashing RGB with a cyclic effect independent of the mechanical movement.
• Adjustments: magnet-to-coil distance and supply voltage, to set the amplitude of the swing.