Fun Devices: Engine DIY

Stirling Engine

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From EngineDIY: BUY NOW: Stirling Engine

Stirling Engine: a very pretty and fully functional model of the famous external combustion heat engine, powered here by a tiny alcohol lamp (with an almost invisible flame). Heat engines produce mechanical motion from a difference in temperature- here the glass cylinder and piston side is kept at high temperature via the flame (to expand the gas within), and the cool side is the metal cylinder and displacer piston which acts as a heat sink to re-cool (and contract) the gas and then send it back to be heated again each cycle. This module also includes a tiny generator and LED circuit. Swipe to see more detail and watch the engine power up. This closed-cycle regenerative heat engine design is attributed to Scottish engineer Robert Stirling back in 1816.

Thermobile: Nitinol Loop Engine

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From EngineDIY: BUY NOWNitinol Loop Heat Engine

Get a sample of Nitinol wire here:
From Educational Innovations: BUY NOW Nitinol Memory Wire Spring 

Thermobile: Nitinol wire loop heat engine- the memory wire straightens out when heated (contact with heat conducting small wheel) causing the wheels to spin, providing mechanical kinetic energy from a cup of warm tea water. Swipe for a demonstration of Nitinol wire, a special alloy of nickel and titanium that can be trained to a specific shape at high temperature- bend it up at room temperature and it will snap back into shape when exposed to moderate heat such as hot tea water. This remarkable property is a type of solid state reversible phase transition known as a martensitic transformation. 

Mini Acoustic Levitator

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From EngineDIY: BUY NOW: Mini Acoustic Levitator

Mini Acoustic Levitator: small pieces of styrofoam become trapped between areas of higher pressure induced by high frequency sound waves. Ultrasonic transducers placed at the top and bottom are basically speakers that emit sound waves at a frequency of 43,000 Hz, which corresponds to a wavelength of 8mm for dry air. If the transducers are positioned just right standing waves are produce with nodes of low pressure at half wavelength intervals- and low mass objects like these foam pellets will be suspended against gravity when placed near one of these nodes. Here we see a stack of three pellets with a spacing of about 4mm which is the expected distribution of the nodes. To place the pellets into the sound stream without disrupting the standing waves this device comes with a small screen with a handle which allows the sound waves to flow through the holes in the mesh and trap piece of foam. Although the device uses sound it appears silent as the frequency used is way above that which humans can hear (20Hz to 20kHz).

 


Tesla's Egg of Columbus

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From engineDIY: BUY NOW: Tesla's Egg of Columbus
This version comes with a 35mm solid aluminum sphere. 

Get the aluminum phiTOP "egg"  here: BUY NOW phiTOP 

Tesla’s Egg of Columbus: an aluminum ellipsoid egg (PhiTOP) mysteriously spins and stands upright in this modern version of Tesla’s famous demonstration from the 1893 World’s Fair in Chicago that first showcased the principles behind wireless power transfer and his AC induction motor. The base has no moving parts- instead special copper windings (very similar to Tesla’s original design) form four electromagnet coils on a circular steel core, and a special circuit supplies each with AC currents in such a way that a rotating magnetic field is created. This rotating magnetic field from the coils under the concave glass induces electric eddy currents to flow in the aluminum ellipsoid- these currents then create their own magnetic field which oppose the initial fields underneath and pushes the ellipsoid to spin. Finally, the ellipsoid top stands up vertically (when spun with sufficient rotational velocity) due to physics similar to that of the tippe-top.