But a small signal across the base is enough to make it work. We’ll focus on the two most common transistors BJTand MOSFET. It’s actually pretty easy, once you learn the basics. In this hands-on guide, you’ll learn how transistors work so that you can use them in your next circuit. This simply implies if we apply signal (voltage/current) across the collector and emitter but not across the base, the transistor will not work. The transistor is a simple component that you can use to build a lot of fun projects. And the transistor behaves like an open switch under the cut-off region. And a transistor operates as a closed switch under the saturation region.Īs soon as a positive signal (in form of voltage and current) is removed across the base of the transistor, the flow of electric current between the collector and emitter becomes zero. In order to use the transistor as a switch, it must be driven into the saturation region with enough base current. When we apply a high enough current at the base of the transistor, it makes a path for the collector current to go through the base towards the emitter. The regions responsible for a transistor to work as a switch are Saturation Region and the Cut-Off Region. When used as an amplifier the DC current gain of the transistor can be calculated by using the below formulaĭC Current Gain = Collector Current (IC) / Base Current (IB) Of the above types, common emitter type is the popular and mostly used configuration. This type of transistor arrangement is not very common due to its unusually high voltage gain characteristics. A transistor is a miniature semiconductor that regulates or controls current or voltage flow in addition amplifying and generating these electrical signals and. Some of the configurations used in amplifier circuits are: The Common Base Transistor Circuit This type of amplifier configuration is a non-inverting voltage amplifier circuit, in that the signal voltages Vin and Vout are in-phase. It can amplify power, voltage and current at different configurations. When base current is removed the transistor becomes fully off, this stage is called as the Cut-off Region and the Base Emitter voltage could be around 660 mV.Ī transistor acts as an amplifier when operating in Active Region. This stage is called Saturation Region and the typical voltage allowed across the Collector-Emitter (VCE) or Base-Emitter (VBE) could be 200 and 900 mV respectively. When this transistor is fully biased, it can allow a maximum of 500mA to flow across the collector and emitter. To bias a transistor we have to supply current to base pin, this current (IB) should be limited to 5mA. The maximum amount of current that could flow through the collector pin is 500mA, hence we cannot connect loads that consume more than 500mA using this transistor. The BC548 has a gain value of 110 to 800 which determines the amplification capacity of the transistor. The BC548 is an NPN transistor so the collector and emitter will be left open (reverse biased) when the base pin is held at ground and will be closed (forward biased) when a signal is provided to base pin.
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