Electronics Engineering

Cut in voltage (Knee voltage): The forward voltage at which the current through the P-N Junction starts increasing rapidly is called as Cut in voltage or knee voltage.

Yes it is illegal

A vector impedance meter is used to measure impedance and phase angle, this is done by calculating voltage and current through an impedance and then calculating Z and phase angle with that, now there are two modes for operation i.e constant current mode and constant voltage mode.

CONSTANT CURRENT MODE

construction = first of all there is a wien bridge oscillator(w) to choose frequency then an AGC amplifier(a) to regulate current then a z switch control(zs) which regulates gain of AGC amplifer,

feedback to AGC amplifier is done by an dc differential amplifier(dc)

dc

|

|

|

w--------->a--------->z

now there is an ac differential amplifier too(ac) which gets one input from the z switch and one from the unknown impedance(imp), and there is a transconductance amplifier too which gets one of his input from the unknown impedance

dc<-------------------------------------------

| |

| |

| |

w--------->a--------->z----------->ac-------------|------------> z meter

| | |

| | |

_____| | |

| | |

| | |

| | |

imp | |

| | |

|________|___>rt___>|

working---> in constant current mode we have to maintain constant current through impedance so current is made to come to unknown impedance from z switch, then that current goes through trans-resistance amplifier, which converts that current to a voltage that is sent to a dc differential amplifier and is compared with a reference voltage in dc differential amplifier then the difference between voltages is amplified and sent to AGC amplifier, so AGC together with z switch this way maintains constant current through unknown impedance,

now for calculation z-magnitude,

ac differential amplifier gets input from unknown impedance and z switch, so difference is amplified and sent to a band pass filter which filters out then the filtered signal is sent to a z-magnitude meter which is calibrated to read z directly.

A: It is a 14 pins dual in line quadruple 2 input positive NOR Gates. It BELONG TO THE 74XX family of IC

ya, it can be negative because as m=Vm/Vc , the value of Vm if taken in negative then modulation index can be naegative

A thermocouple is a device which generates an electrical charge when

heated. It is often used on a boiler to indicate that the pilot light

is on and hot, so it should be safe to allow gas to pass to the main

burner for heating water, your house, etc. Should the pilot light go

out, the thermocouple will sort of "tell" the boiler to shut off the

gas, as it isn't safe to fire up.

A thermostat is used as a switch, which goes on and off at a certain

temperature. For example, in a boiler it will tell the boiler that the

water in the circuit is plenty hot enough and that it doesn't need to

be heated any more, in your house it will tell your central heating

that the room is warm enough and doesn't need heating any more and in

your car it would say that your engine is too hot and that the radiator

valve should open, and perhaps the cooling fan should turn on.

It is a Butyro Refrective Index meter. Generally, it is used by Dairy Industry to measure the Brix of oil present in the milk. Milk oil basically are present in the BR range of 40-43. This BR set up is specially used to check adulteration in milk, if adulterated with external oil to increase the fat percentage in the milk.

It acts as synchronous motor by consuming power from the other generator....

(a) Charge Will increase

(b) Potential difference will stay the same

(c) Capacitance will increase

(d) Stored energy will decrease

CMOS is a dynamic power consumer...whereas BJT consumes power always....

cmos consumes power only while switching from one astate to another state...i.e while switching

The sharing of current between different components in an AC circuit

Silicon = 0.7v : Germanium = 0.3v

let the mosfet be biased in saturation regior.

thus drain current in independent of drain to sourse voltage,

the VI chara. is a curve, when this is extended till X axis at pt. Vds=-Va

this is similar to effect in transistor

the o/p resistance is slope of V-I chara.. it should ideally be infinite, but has some finite value due to "CHANNEL LENGTH MODULATION"

A: Those voltages are called distribution voltages to differentiate from transmission voltages. And that varies from state to state and locals . Usually around 10kv to 20 kv

A: There is no zeroing resistor the leads resistance are the zeroing resistor. there is however a pot where the zero can be accomplished by adjusting the current flow out of the meter to measure the voltage to determine the resistance. that pot is an adjustment to compensate for an old internal battery drift. If not changed periodically it may become a useless meter because zero cannot be achieved

Pn-40,means pressure nominal for a valve

Maybe, but not sure info would be useful.

You can use ohmmeter to check that a tube's filament is intact.

Broken/burned-out filament is most likely reason for dead tube.

I would simply suggest taking a linear potmeter of approx a value 700% higher. Then connect a resistor of the original value +20% (approx) across linear pot middle and either side. This makes it working almost like the original logaritmic potmeter. If you want reverse log or dual log, then just connect the resistor to the other leg from middle, or halve the resistor value and connect both from the middle and to each side.

If you are unsure how it works, then a spreadsheet provides you with abilities to simulate how it will work.

Example of a "Linear Log Pot":

A project I started on needed a reverse log taper of 10 K.

This was nowhere to be found and I thought, lets cheat.

I started with spreadsheet and put in a few formulas for parallell connection of resistors.

I found that a 68K linear and a 12K resistor in parallell would give much the same performance curve as a logaritmic taper.

It gives approx the same resistance and approx the same voltage (if used as a voltage divider) as a Log and reverse log taper.

Propagation Delay

In digital logic, every gate has got some finite amount of delay because of which the

change in the output is not instantaneous to the change in the input.

In simple terms, the times it takes for an input to appear at the output is called the

propagation delay.

In Figure 6, tPHL, describes the time it takes for an input to cause the output to change

from logic-level-high to logic-level-low.

Similarly, tPLH, refers to the delay associated when an input change causes the output to

change from logic-level-low to logic-level-high.

The overall delay is average of these two delays.

Teleconferencing

the early effect is a width base modulation due to which collector curren

inc by inc of c-b

voltage

When reading the needle on an analog meter, you can get a slightly different reading depending on the position of your eye relative to the needle and the scale behind the needle. This is parallax. The digital meter reads the exact value measured (to the accuracy of the meter), and then displays it in the form of "numbers" or "digits" so your eye is not interpreting the value from a scale.