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What do you need to know about bipolar NPN transistors?
One other point to remember about Bipolar NPN Transistors. The collector voltage, ( Vc ) must be greater and positive with respect to the emitter voltage, ( Ve ) to allow current to flow through the transistor between the collector-emitter junctions.
How are negative electrons used in a NPN transistor?
So in a NPN Transistor it is the movement of negative current carriers (electrons) through the Base region that constitutes transistor action, since these mobile electrons provide the link between the Collector and Emitter circuits.
What is the relationship between base and emitter in NPN?
The voltage between the Base and Emitter ( VBE ), is positive at the Base and negative at the Emitter because for an NPN transistor, the Base terminal is always positive with respect to the Emitter. Also the Collector supply voltage is positive with respect to the Emitter ( VCE ).
How big is a defpom transistor cross reference?
TO-72 EBC 2N2857 NPN 15V 40mA 200mW 12,5dB 450MHz 1,6GHz 4,5dB 450MHz TO-72 2N3663 NPN 12V 30mA 350mW 1,5dB 200MHz 700MHz 6,5dB 60MHz TO-92 BCE 2N3904 (pdf) NPN 40V 200mA 625mW 300MHz 5dB 15,7kHz
How to calculate base current for NPN transistor?
Calculate the base current Ib required to switch a resistive load of 4mA. Therefore, β = 200, Ic = 4mA and Ib = 20µA. One other point to remember about NPN Transistors.
What are the properties of a bipolar junction transistor?
One of the most important properties of the Bipolar Junction Transistor is that a small base current can control a much larger collector current. Consider the following example. A bipolar NPN transistor has a DC current gain, ( Beta) value of 200. Calculate the base current Ib required to switch a resistive load of 4mA.
How big is the collector current in a BJT?
Collector current is 0.72 mA. Many saturated transistor circuits allow collector current to be ten or twenty times larger than base current, but not in this case – no current gain is required of the transistor (actually less than one). Not shown is the current that might flow from the 5v logic output.