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How fet is used as vvr?
FET AS A VOLTAGE -VARIABLE RESISTOR (VVR):FET is operated in the constant current portion of its output characteristics for the linear applications .In the region before pinch off , where Vds is small the drain to source resistance rd can be controlled by the bias voltage Vgs.The FET is useful as a voltage variable resistor (VVR) or Voltage Dependent resistor.In JFET the drain source conductance gd = Id/Vds for small values of Vds which may be expressed as gd = gdo [ 1-( VgsVp)1/2 ] where gdo is the value of drain conductance when the bias voltage Vgs is zero.The variation of the rd with vgs can be closely approximated by rd = ro / 1- KVgs ro - drain resistance at zero gate bias and K constant dependent upon FET type.Small signal FET drain resistance rd varies with applied gate voltage Vgs and FET act like a VARIABLE PASSIVE RESISTOR.Advantagesof JFETVery high input impedance order of 100 ohmOperation of JFET depends on the bulk material current carriers that do not cross junctionsNegative temperature coefficientsVery high power gainSmaller size longer life and high efficiencyAc drain resistance rd it is the ratio of change in drain - source voltage to the change in drain current at constant gate source voltageTransconductance it is the ratio of change in drain current to the change in gate source voltageat constant drain source voltageAmplification factor it is the ratio of change in drain source voltage to the change in gate source voltage at constant drain current.
Why DC supply is used in control circuit?
dc supply is used for control circuit because dc current is an independent source .
Can a zener diode be used in place of ic 7805?
no, zener diode regulators can supply no more than a few tens of milliamperes to a load while maintaining stable regulation. a 7805 three terminal linear regulator IC is designed to provide up to 1 ampere to a load while maintaining stable regulation.Note: three terminal linear regulators like the 7805 already contain an internal zener diode acting as a voltage reference, but its internal load is only 1 or 2 milliamperes to keep it very stable.
What is the standard unit for resistance?
ohm
What is V-I characteristics of zener diode?
Work in reverse bias.(breakdown at a particular voltage to keep the volt. constant so used as voltage regulator) same as diode when forward biased.
Is a battery provides not a source of constant current or a source of constant voltage?
Batteries will provide a source of constant voltage. A battery also can be used to produce an electrical current immediately upon a necessary connection.
78xx regulater as a constant current source?
The 78xx regulater can be used as a constant current source, by connecting the output to the input side of a series resistor, and the "ground" to the other side of the resistor. Do not connect the "ground" to real ground - leave it floating.Since the 78xx maintains a constant voltage differential between output and ground, there would be a constant current through the resistor.
What is function of 7805 IC?
Ic 7805 we are mostly used for regulator & its minimum input voltage is 7.2 V. Sandeep Chauhan
Why you use capacitor with voltage regulator ic 7805?
in ic 7805 their is two capacitor is used one of them is used for the settling/transient time and another is used to provide inductive effect....
Is a transformer a source of constant electric current?
A; Terminology is not correct a transformer is not really a source but rather a device to transform one source of power to some power that can be used as required minus efficiency of power transfer
Is a transformer one source of constant electric current?
A; Terminology is not correct a transformer is not really a source but rather a device to transform one source of power to some power that can be used as required minus efficiency of power transfer
What is one source of constant electric current?
Cells and batteries.A more detailed answerIn general, most power supply sources - including cells and batteries - cannot supply either a truly constant current or voltage.Because most load devices are designed to require a nearly constant voltage - and not a specific constant current. - most power supplies - including cells and batteries - are designed to supply a given output voltage whatever the current that is being drawn, provided of course that the current stays within a pre-determined designed range of output current values.One definition of "constant current source" is that it has zero output resistance, which in practice cannot exist.However, a transistor can act as a constant current source if biased and used in that manner. This can also be done using one of the several standard "voltage regulator" components - which are available from electronics parts suppliers - because they can be hooked-up to act as constant current sources to operate over a small range.
You are making a battery low indicator with IC 7805 why is IC 7805 used in it?
A: an lm7805 Is a positive regulator if enough voltage is available it will regulate to ~5 volts that is only purpose no matter how it is used.
What source used by electronic mail?
current
Is electrical current a source of electricity?
A generator can be used as a temporary source of power
What is the purpose of constant voltage transformer?
The term 'constant voltage transformer' is used to differentiate the operation of transformers that are intended to change voltage levels, from those intended to change current levels -a current transformer (CT), for example, is termed a 'constant current transformer'.
Which welding process uses a constant current power source?
smaw and tig(gtaw) are using CC source. because these both types using manual wire feeding. so welder can not able to maintain constant arc length. change in arc length will change voltage. so it needs power supply which should not affected by this arc length = voltage changes. that's why CC type is used for these process. in CC type source change in voltage will not change current much.
