Velleman&reg; Steam-Engine Sound Generator Kit Just What Choo Need if you want to sound like a steam engine, and who among us doesn't? This Velleman steam-engine sound generator kit comes with circuit board, components, battery connectors, speaker and instruction sheet. You add solder, a soldering iron and a 9V battery. Volume and (implied) speed are adjustable and there's a horn button, so it'll go both choo-choo and whoo-whoo. Great for train hobbyists or people bored with their doorbell.