Build this simple Magnetic Pendulum with very few components. Hall effect sensor is used to detect the presence of magnetic field, and "push" the pendulum in the exact moment. Electromagnet is "ON" during only 20mS and battery power drain is low.
Step 1: Images of Device - Watch Video on Last Step.
Step 2: Phase 1
Step 3: Phase 2
Step 4: Phase 3
Step 5: Circuit & Main Components
Hall sensor: UGN-3503-U
IC1: LM358N( dual OP amp )
IC2: CD4001(quad cmos nor gate )
FET1: IRFD-120( n-channel power mosfet )
Step 6: Hall Sensor Operation
Step 7: Direction Detector
IC1 output will be low when pendulum is approaching it. It will be high when it is moving away.
Step 8: Monostable
when IC1 out is high, monostable IC2 will trigger with a 20mS output pulse.
Step 9: Driving FET
pulse from IC2 biases mosfet gate and electromagnet L1 conducts pushing pendulum. It also drives LED on.
Step 10: Voltage Drop
diode D1 drops 6V from battery to around 5.3v ( optimum voltage ) . Hall sensor will break down above 6v.