16-02-2010, 10:36 AM
i am the student of electrical engineering dept. i want to do the project on 'van de graaff generator'. please help me by giving the description and the required tools for the generator. thank you.
16-02-2010, 10:36 AM
i am the student of electrical engineering dept. i want to do the project on 'van de graaff generator'. please help me by giving the description and the required tools for the generator. thank you.
16-02-2010, 05:59 PM
A Van de Graaff generator is an electrostatic generator which uses a moving belt to accumulate very high electrostatically stable voltages on a hollow metal globe on the top of the stand. The Van de Graaff generator can be thought of as a constant-current source connected in parallel with a capacitor and a very large electrical resistance.
This article discusses a MEMS implementation of a planar Van de Graaff generator in a standard MUMPs process.It can generate high voltages in autonomous MEMS devices. MEMS power conversion based on mechanical transport of charge analogous to the macro-scale Van de Graaff generator is discussed. electrical actuators, micro-combustion engines, vibrations, etc supply the mechanical energy needed for this conversion. Basic construction: In the typical Van de graaff generator a belt consisting of insulated conductive tiles is positively charged by a voltage source and the charge is delivered to and deposited in a hollow metal sphere (a dome). The conductive tiles are charged by another voltage source with a negative charge of the same magnitude as the one they delivered up, and then travel back to ground. A positive charge accumulates on the dome and potentially very high voltages accumulates on the dome. MEMS implementation A planar Van de Graaff generator prototype was designed in the standard MUMPs process(a surface micromachining process).Also, a metal layer is desirable for the implementation of low-resistance contacts for the shuttle. The generator contains capacitor Cc and Cd bottom plates, and the contacts for the shuttle.The shuttle is made of a Poly 1 plate, reinforced with Poly 2.The main contribution to Cp comes from the capacitance between the shuttle rails and ground.Metal(gold) contacts are needed to connect the shuttle sequentially to Vc and Vo. semiconductor switching maybe utilised in the design. full report: van de graaff generator.pdf (Size: 565.56 KB / Downloads: 252) |
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