Lego SP Daylight Locomotive with Steam Generator - Stationary

This video shows the operation of a water-based steam generator built into a Lego model of the famous SP 4449 Daylight locomotive. The steam generator is based on the working disc of an ultrasonic humidifier which creates a stream of mist. The control board is located in the tender. Besides driving the driver wheels, the motor internal to the boiler drives an air pump which gives a puff of air into the stack once per revolution of the wheels. The water has a small amount of food coloring added to make the steam more visible.