Increasing base current causes a proportionate increase in collector current - proportionate to hFe, unless the transistor is operated outside of linear mode.
The output current of a transistor is controlled by the current in the 'base' input: Increasing the control current will increase the output current in a more or less linear fashion. In the saturation region, this is no longer true: The transistor is nearing the limits of how much current it can conduct, so increasing the control current further has little or no effect. When using a transistor as an amplifier, you want to stay away from the saturation region as it would distort the signal you are amplifying. When using a transistor as an on/off switch, as in digital circuits, being in the saturated region is 'on' and a normal mode of operation.
A: The small base current will control the collector current flow by adding a resistor this changes of current flow will be evident as a voltage amplifier.
GAIN is a function of load current but basically a small current in the base will make a big change of collector current therefore making a transistor a voltage amplifier as opposed to a current amplifier
depends on the circuit it is used in:CE/CS is inverting voltage amplifierCC/CD is noninverting current amplifierCB/CG is noninverting voltage amplifier
A: As current begins to flow the action on a resistance will be a voltage drop which is inversely proportional to the current. Making it a voltage amplifier as opposed to a tube where it is a current amplifier
The output current of a transistor is controlled by the current in the 'base' input: Increasing the control current will increase the output current in a more or less linear fashion. In the saturation region, this is no longer true: The transistor is nearing the limits of how much current it can conduct, so increasing the control current further has little or no effect. When using a transistor as an amplifier, you want to stay away from the saturation region as it would distort the signal you are amplifying. When using a transistor as an on/off switch, as in digital circuits, being in the saturated region is 'on' and a normal mode of operation.
A PNP transistor has no advantage or disadvantage over an NPN transistor in its ability as an amplifier. Rather, the current-handling capacities of the transistor determine if it's usable as an amplifier.
A transistor works as am amplifier by virtue of the fact that you can control the current in one path with a smaller current in another path. In a typical class A (common emitter) configuration, a certain current from base to emitter will create a corresponding current from collector to emitter. Increasing or decreasing the base-emitter current will cause a corresponding increase or decrease in the collector-emitter current, by a ratio that is defined as hFe, or beta-gain. Of course, this means that you have to properly bias the transistor, and understand the nature of hFe. You can operate a transistor in cutoff mode or saturated mode if you exceed the hFe limits. Within the limits, a properly biased transistor exhibits a (generally) linear operation.
A: The small base current will control the collector current flow by adding a resistor this changes of current flow will be evident as a voltage amplifier.
GAIN is a function of load current but basically a small current in the base will make a big change of collector current therefore making a transistor a voltage amplifier as opposed to a current amplifier
depends on the circuit it is used in:CE/CS is inverting voltage amplifierCC/CD is noninverting current amplifierCB/CG is noninverting voltage amplifier
output current is zero
Transistor increase the strength of a weak signal from the base
A Darlington transistor is a composite transistor. The definition is a combination of two or more transistors that have the purpose of increasing the current gain.
The same h parameter model is used for npn and pnp transistors because gain is gain. It does not matter if you are using a negative or a positive system. So long as you are consistent in your calculations, you will get the correct results. In an NPN transistor operating in class A, if you increase the base current by increasing the base voltage, you will increase the collector current which decreases the collector voltage. In a PNP transistor operating in class A, if you increase the base current by decreasing the base voltage, you will still increase the collector current, which will increase the collector voltage.
A transistor used as a switch is operated in saturated mode, where the ratio of base-emitter current over collector-emitter current is far more than hFe, or beta gain. The transistor is either fully on or fully off in this mode. A transistor used as an amplifier is operated in linear mode, where the ratio of base-emitter current over collector-emitter current is equal to or less than hFe, or beta gain. The transistor is partially on in this mode, and is operating as a current controlled current sink.
A: As current begins to flow the action on a resistance will be a voltage drop which is inversely proportional to the current. Making it a voltage amplifier as opposed to a tube where it is a current amplifier