Heat sinks are needed for power transistors because they pass large currents. Waste heat is produced in transistors due to the current flowing through them. Crocodile Clipĭo not confuse this temporary heat sink with the permanent heat sink (described below) which may be required for a power transistor to prevent it overheating during operation. A standard crocodile clip can be used as a heat sink. Transistors can be damaged by heat when soldering so if you are not an expert it is wise to use a heat sink clipped to the lead between the joint and the transistor body. Transistor Leads for Some Common Case Styles Soldering Transistor ![]() This is the opposite of IC (chip) pin diagrams which show the view from above. Please note that transistor lead diagrams show the view from below with the leads towards you. The drawings on the right show the leads for some of the most common case styles. If you are lucky the orientation of the transistor will be clear from the PCB or stripboard layout diagram, otherwise you will need to refer to a supplier's catalogue to identify the leads. Please take care with this because a wrongly connected transistor may be damaged instantly when you switch on. Transistors have three leads which must be connected the correct way round. They have different circuit symbols and properties and they are not (yet) covered by this page. These terms refer to the internal operation of a transistor but they are not much help in understanding how a transistor is used, so just treat them as labels! In addition to standard (bipolar junction) transistors, there are field-effect transistors which are usually referred to as FETs. The leads are labeled base (B), collector (C) and emitter (E). If you are new to electronics it is best to start by learning how to use NPN transistors. Most transistors used today are NPN because this is the easiest type to make from silicon. The letters refer to the layers of semiconductor material used to make the transistor. There are two types of standard transistors, NPN and PNP, with different circuit symbols. The amount of current amplification is called the current gain, symbol hFE. In many circuits a resistor is used to convert the changing current to a changing voltage, so the transistor is being used to amplify voltage.Ī transistor may be used as a switch (either fully on with maximum current, or fully off with no current) and as an amplifier (always partly on). Transistors amplify current, for example they can be used to amplify the small output current from a logic chip so that it can operate a lamp, relay or other high current device. Thus, the control circuit can be independent of the circuit being controlled. two terminals act like switch contacts, while the third is used to turn the switch on and off. Transistors, on the other hand, have three terminals. They only respond to switch the voltage across them. They are mainly used in chopper and inverter applications.ĭiodes are uncontrollable switches having only two terminals. ![]() In power electronics, where the main objective is the efficient control of power, transistors are invariably operated as switches. Transistors have two basic types of applications: amplification and switching. Transistor is made from semiconductor materials i.e. Transistor is an three layer PNP or NPN semiconductor device with two junctions.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |