How can a PNP transistor be used as a switch?
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For a PNP transistor, the Emitter potential must be positive with respect to the Base. Then the transistor operates as a “single-pole single-throw” (SPST) solid state switch. With a zero signal applied to the Base of the transistor it turns “OFF” acting like an open switch and zero collector current flows.
What is CB configuration in transistor?
Definition: The configuration in which the base of the transistor is common between emitter and collector circuit is called a common base configuration.
How a transistor acts as a switch?
The transistor operates as a Single Pole Single Throw (SPST) solid state switch. When a zero input signal applied to the base of the transistor, it acts as an open switch. If a positive signal applied at the input terminal then it acts like a closed switch.
How the NPN PNP transistor works as a switch?
NPN Transistor as a Switch Based on the voltage applied at the base terminal of a transistor switching operation is performed. When a sufficient voltage (VIN > 0.7 V) is applied between the base and emitter, collector to emitter voltage is approximately equal to 0. Therefore, the transistor acts as a short circuit.
What is PNP switch?
PNP = Switched Positive. NPN = Switched Negative. “Switched” refers to which side of the controlled load (relay, small indicator, PLC input) is being switched electrically. Either the load is connected to Negative and the Positive is switched (PNP), or the load is connected to Positive and the Negative is switched (NPN …
What are the applications of CB configuration?
Applications. This arrangement is not very common in low-frequency discrete circuits, where it is usually employed for amplifiers that require an unusually low input impedance, for example to act as a preamplifier for moving-coil microphones.
Why CB configuration is preferred for amplification?
Common emitter circuit is preferred over a common base circuit in amplifiers because the resistance of the common emitter circuit is much less than that of the common base circuit. Also the power gain in the common emitter circuit is much higher than that in a common base circuit.
Can we replace PNP transistor with NPN?
Generally, the PNP transistor can replace NPN transistors in most electronic circuits, the only difference is the polarities of the voltages, and the directions of the current flow. PNP transistors can also be used as switching devices and an example of a PNP transistor switch is shown below.
What is the working principle of PNP transistor with CB configuration?
The working principle of pnp transistor with CB configuration is same as the npn transistor with CB configuration. The only difference is in npn transistor free electrons conduct most of the current whereas in pnp transistor the holes conduct most of the current.
Can a PNP transistor be used as a switch?
PNP Transistor Switch We can also use the PNP Transistors as a switch, the difference this time is that the load is connected to ground (0v) and the PNP transistor switches the power to it. To turn the PNP transistor operating as a switch “ON”, the Base terminal is connected to ground or zero volts (LOW) as shown.
Why is the base voltage negative in a PNP transistor?
For the PNP transistor, the base terminal is always negatively biased with respect to the emitter. In this switching, base current flows when the base voltage is more negative. Simply, a low voltage or more negative voltage makes the transistor to short circuit otherwise, it will be open circuit.
What is the output current of a PNP transistor at 5V?
Therefore, as the base current is greater than 56.8 micro ampere current, the transistor will be driven to saturation i.e., it is fully ON, when 5V is applied at the input. Thus, the output at the collector becomes approximately zero. PNP transistor works same as NPN for a switching operation, but the current flows from the base.