![]() ![]() Transistors cannot amplify source voltage Vcc.Generally people think amplifiers can amplify any signal up-to any level but that is not so true. Pressing the button over here will light up the LED because now the circuit becomes complete from power source to ground. But a small base signal is enough for it to operate. This simply means if we applied signal (voltage/current) across collector and emitter but not on the base, the transistor will not work. Power (+5V) → resistor 280 W → LED → Collector-base-Emitter → ground It just bypasses the signal present of the collector while having active base condition.Īs soon as we press the button a signal (in form of voltage and current) will be received by the base of BJT which in turn allows electric current to pass from collector to emitter.Ĭurrent can flow through the circuit in this way (electrons flow in opposite direction of current): When a positive signal (+) present on its base it will make a path for collector current to go through from the base towards the emitter. Now we will see how the transistor works as a switch, here we are using an NPN transistor. When the base current is removed the transistor will turn off completely, This stage is known as the Cut off Region.This stage is named Region of Saturation. If this transistor is fully biased then a maximum of 100 mA can flow through the collector and emitter.Conclusion with statement 2 and 3 is, 0.5 mA base current IB drive 10 mA Collector current IC and 5 mA IB can drive 100 mA IC.To bias a transistor we must supply a base pin with current, The current (IB) is limited to 5 mA.The maximum current able to flow through the Collector pin is 100 mA, We can not therefore connect loads which consume more than 100 mA using this transistor.Gain value of BJT BC547 is between 110 to 800.It is mainly used for signal amplification. ![]() In NPN majority charge carriers are electrons while in PNP majority carriers are holes. Most common category of Transistors is BJT – Bipolar Junction Transistor.Īs these are semiconductor devices, they are of two types one is NPN and other is PNP. Transistor is a three terminal semiconductor device which is used in switching and to amplify the base signal but now they are mostly used in embedding integrated circuits. ![]()
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