tailieunhanh - Build Your Own Combat Robot phần 5

FET một công trình một cái gì đó giống như một thực hiện bán dẫn của một relay. Một FET có hai nhân vật chính, được biết đến như là nguồn và cống, kết nối với một kênh vật liệu bán dẫn. Thành phần của vật liệu là như vậy mà hiện tại bình thường không thể lưu thông qua nó. Một dẫn thứ ba, được gọi là các cửa khẩu | 142 Build Your Own Combat Robot are called the Field Effect Transistor FET and the Metal Oxide Semiconductor Field Effect Transistor MOSFET . For the following discussions FET will be used as a generic term to represent both MOSFETs and FETs. Field Effect Transistor An FET works something like a semiconductor implementation of a relay. An FET has two leads known as the source and the drain connected to a channel of semiconductor material. The composition of the material is such that current cannot normally flow through it. A third lead called the gate is connected to a conductive electrode that lies on top of the semiconductor junction but is insulated from it by a thin non-conducting layer. When voltage is applied to the third electrode it creates an electric field that rearranges the electrons in the semiconductor junction. With the field present current is able to flow between the source and drain pins. When the gate is driven to a low voltage the electric field reverses and current is unable to flow. The FET acts as a voltage-controlled switch where an applied voltage to the gate will control the current flow between the drain and source. The layer of insulation between the gate and the source drain channel must be very thin for sufficient field strength to reach from the gate into the semiconductor channel. This thinness makes the FET vulnerable to being damaged by too high a voltage. If the voltage between either the drain or source and the gate exceeds the breakdown voltage of the insulation layer it will punch a hole through the layer and short the gate to the motor or battery circuit. This can be caused by connecting the FET up to too high a voltage or simply by zapping the FET circuit with static electricity. You should be careful when handling FETs and attached electronics to avoid accidentally discharging static electricity into them. It is also good practice to use FETs with a voltage rating of twice the battery voltage you wish to run your motors on .