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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 ).
Why does a NPN trigger a PNP signal?
Depending on the sensor’s internal wiring, there might be some current flow from the NPN input to the sensor, for example there may be reverse current that “leaks” through a protection diode or an LED in the sensor. This current flow might be high enough to falsely trigger the NPN input.
Which is the third connection of the NPN transistor?
The third connection is to the base of the npn transistor and the collector of the pnp transistor, and is named simply the gate, or the cathode gate. To begin the cycle of operation, the gate is at, or close to, the potential of the cathode, so the npn transistor is switched off.
Can a sensor have both PNP and NPN?
The sinking / sourcing logic is the same as for the Black wire. That is, if the sensor is PNP for the Black wire, it is also PNP for the White wire. I have never seen a sensor with mixed PNP and NPN outputs, but perhaps some specialty types exist on the market. An NPN input is looking for the input to be connected to GND to respond.
When does BJT at edge of saturation occur?
Saturation occurs when increasing base current does not reduce collector voltage. as such it s depedant to some extent on what the load is, Depending on the degree of precision needed and what you’re trying to do you can use different approximations for saturation voltage.
What do we do if VCE, sat is given?
If Vce,sat is given we use that but if it isn’t we make sure that the base-collector junction is neither forward nor reverse biased and find it ourselves. The TA horribly failed at explaining this so I thought I would ask for the infinite wisdom of random strangers online.
What kind of amplifier is used in a NPN transistor?
If a suitable DC “biasing” voltage is firstly applied to the transistors Base terminal thus allowing it to always operate within its linear active region, an inverting amplifier circuit called a single stage common emitter amplifier is produced. One such Common Emitter Amplifier configuration of an NPN transistor is called a Class A Amplifier.
How is the BJT differential pair a differential amplifier?
The differential pair is a differential amplifier—we express its performance in terms of differential and common-mode gains. Consider the BJT differential pair: 2 1 Also, we know that: Therefore, the emitter currents can be written in terms of the base voltages as: Of course, we know that Ii i= EE12+ , thus:
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.