Electronics Engineering

The number of turns or windings of a transformer can vary. There can be more in the primary, or more in the secondary, or there can be an equal number in a transformer that is simply used for isolation (an isoformer). More turns in the primary than secondary will create a step down transformer. More turns in the secondary are found in a step up transformer. The transformers on power poles have more turns in the primary to step the line voltage down for delivery to residential customers.

Basically, a Q-point of any device gives information about the operating current & voltage of that particular device..This would help us to know about the max. & min. current or voltage upto which the can be operated safely.

it will control the flow of electrons between the source and drain,the controlling will be depends upon the input voltage to the substrate.

buffer circuits helpful in overcoming the impedance matching problem.for example if we want to send a signal from one devise to other ,if there is no impedance matching between this two then signal is not transfered.now if we use buffer in between these two devises then the buffer without changing the signal shape or value it simply transffers the signal

If you don't it could fry your equipment. A capacitor can hold a charge for anextremely long time even years depending on the physical size and capacitance. It can hold a strong enough charge to kill.

IIR filters are recursive and FIR filters are non-recursive. Also FIR filters are linear phase and IIR filters are not; several applications are sensitive to non-linear phase (communications, medical, etc). In implementation, IIR filters require fewer taps (smaller order) and thusly are easier to implement and have fewer zeros. Also FIR filters are always stable, while IIR filters can often become unstable in implementation. The previous answer is correct about delays.

Yes, SiO2 is used for isolation and it can be grown easily when compared to other materials. The process is also simple as it only required oxidation of the already existing Si layer

messenger

It is because there is a light bulb and things like that......

Solution

Let fh is the highest frequency and fl is the lowest frequency.

Bandwidth = fh - fl = 4000 - 40 KHz = 3960 KHz = 3.96 MHz

In dc equivalent circuit of an amplifier all capacitors are replaced by open circuit because capacitor block dc.

As ,

				Xc=1/2πfC

We know that that frequency of dc is zero so Xc will infinite so we replace all capacitors with open circuit.

A: this chip is defined as a timer but it can be used for other reasons and applications.

it is not grounded

A: in actuality they do die if they reach to the other line potential grounding is not involved is the potential of two point that does it

The power dissipated across a resistor, or any device for that matter, is watts, or voltage times current. If you don't know one of voltage or current, you can calculate it from Ohm's law: voltage equals resistance times current.

So; if you know voltage and current, power is voltage times current; if you know voltage and resistance, watts is voltage squared divided by resistance; and if you know current and resistance, watts is current squared times resistance.

Fluxvalve Theory

10. The fluxvalve , consists of a sensitive pendulous element which is free to swing within limits (usually ± 25°) but fixed to the aircraft in azimuth. The element is suspended by a Hooke's Joint with the whole assembly being hermetically sealed in a case partially filled with oil to dampen oscillations. A deviation compensator is usually mounted on top of the unit.

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11. The pendulous detector element resembles a three spoke wheel with the spokes 120° apart and slotted through the rim. The rim forms a collector horn for each spoke. The horns and spokes are made up of a series of metal laminations having a high magnetic permeability. Each spoke has a vertical cross-section similar to that shown in Fig 12-2. The spoke consists of two superimposed legs which are separated by plastic material and opened out to enclose the central hub cone. This cone has an exciter coil wound round it on a vertical axis, and each spoke has a pick-off coil wound round both legs on a horizontal axis. The exciter coil is fed with 400 Hz single phase AC. The output of the secondary or pick-off coil is an 800 Hz single phase AC current, the amplitude and phase representing the relationship of magnetic North to the aircraft longitudinal axis (magnetic heading).

Fig 12-2: Vertical Cross-section of Spoke

12. In order to appreciate the operation of the fluxvalve it is necessary to consider an individual spoke. The function of a spoke will be developed in a series of diagrams (Figs 12-3 to 12-10).

13. If a single coil is placed in a magnetic field, the magnetic flux passing through the coil is maximum when the axis of the coil is in line with the direction of the field, zero when the coil lies at right angles to the field, and maximum but of opposite sense relative to the coil when turned 180° from its original position. For a coil placed at an angle θ to a field of strength H (Fig 12-3) the field can be resolved into two components, one along the coil equal to H cos θ and the other at right angles to the coil equal to H sin θ. The H cos θ component is parallel to the coil and is the effective flux producing element. Therefore, the total flux passing through the coil is proportional to the cosine of the angle between the direction of the coil axis and the direction of the field. The coil output curve is shown at Fig 12-4. If the coil is in the horizontal plane with its axis parallel with the aircraft longitudinal axis, its output is affected by the horizontal component of the Earth's magnetic field and the flux passing through the coil is proportional to the magnetic heading of the aircraft.

Fig 12-3: Magnetic Flux Components

Fig 12-4: Variation of Flux with Theta

14. Unfortunately, the simple concept just described cannot be used without modification as a heading reference system for two important reasons. Firstly, the voltage induced into a coil depends

FIS Book 4: Instruments 74

on the rate of change of flux. Therefore, once established on a heading, there would be no change of flux and, consequently, no induced voltage. Secondly, the output of the simple detection device would be subject to heading ambiguity, i.e. there are always two headings which cause the same induced output voltage. Therefore, the problem that must be solved is how to produce an output waveform which is proportional in some way (frequency, phase or amplitude) to the components of the Earth's field and linked with the coil. This is achieved in the fluxvalve by introducing an alternating magnetic field in addition to the static field caused by the horizontal component of the Earth's magnetic field.

15. Fig 12-5 shows the relationship between flux density (B) and magnetizing force (H) known as the hysteresis loop for the permalloy commonly used in the legs of the flux valve spokes. Permalloy has a very high magnetic permeability (μ = B/H) and a corresponding low hysteresis loss. In the following discussion the hysteresis loop is represented by a single line curve.

Fig 12-5: Hysteresis Curve for Permalloy

Fig 12-6: Simple Fluxvalve

Fig 12-7: The Effect of Excitation Current in the Top Leg Only

16. One spoke of the three-spoke fluxvalve is shown diagrammatically in Fig 12-6. It consists of a pair of soft iron (usually permalloy) cones each wound with a primary coil. The winding on one core is the reverse of that on the other. The AC supply is just sufficient, at peak power, to saturate magnetically each of the parallel soft iron cores. A secondary coil, wound round the two primaries, is linked with the circuit, and any change of flux through it induces a voltage and current flows.

17. Fig 12-7 shows the 400 Hz alternating flux induced in the top leg by the excitation current considering only the top leg of the spoke and the effect of the excitation.

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18. Now considering the bottom leg only; the flux induced in this leg by the excitation current will at any instant be in the opposite direction to that induced in the top leg, i.e. the flux in the bottom leg is 180° out of phase with the flux in the top leg as shown in Fig 12-8.

19. Since the top and bottom legs are identical, the amplitudes of the flux of the two legs are equal but 180° out of phase with each other relative to the pick-off coil, which is wound round both legs. Therefore, the resultant flux cutting the pick-off coil, which is the algebraic sum of the flux in the top and bottom legs is zero as shown in Fig 12-9.

Fig 12-9: The Effect of the Excitation Current in Both Legs

Fig 12-8: The Effect of the Excitation Current in the Bottom Leg Only

20. If the horizontal component of the Earth's magnetic field (H) is now added in line with the spoke, it will induce a steady flux in both legs of the spoke which will be added to the flux due to the excitation current. The effect, as shown in Fig 12-10, will be to bias the datum for the magnetizing force, due to the excitation current, on the B-H curve by an amount equal to H. The strength of the excitation current is so arranged that the effect of the introduction of the Earth's magnetic field component is to bring the flux density curves in Fig 12-10 onto the saturation part of the hysteresis curve. The resultant flux cutting the pick-off coil, which is the algebraic sum of the fluxes in the top and bottom legs, will no longer be

Fig 12-10: The Combine Effects of the Excitation Current and the Component of the Earth's Field

zero but will have a resultant proportional in amplitude to heading. The emf induced in the pick-off coil

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is proportional to the rate of change of flux cutting the coil and therefore will have a waveform approximating to a sine wave at 800 Hz, i.e. twice the frequency of the excitation current as shown in Fig 12-10. It has been found by experiment that the amplitude of the emf is proportional to H. Therefore, the emf in the pick-off coil is a measure of H, i.e. the horizontal component of the Earth's magnetic field in line with the spoke. This should be apparent from Fig 12-10 in that, if a greater H is detected, the excitation current is biased further from the mid-point of the hysteresis curve, and the imbalance between the upper and lower leg fluxes will increase. Therefore, a greater resultant flux exists which will induce an emf of greater amplitude in the pick-off coil. A plot of the amplitude of the pick-off coil output voltage would show that it varies as the cosine of the magnetic heading.

21. Limitations of the Simple

Single Spoke Detector. It should be apparent that there are two magnetic headings corresponding to zero flux (90° and 270°) and two headings corresponding to a maximum flux. The two maximum values give the same reading on an AC voltmeter since the instrument cannot take into account the direction of the voltage. For any other value of flux (other than zero), there will be four headings corresponding to a single voltmeter reading. This ambiguity is overcome by using a fluxvalve having three spokes (each spoke similar to the single spoked device previously discussed) with 120° separation as shown in Fig 12-11. Regardless of the heading, at least two of the spokes will have a voltage induced and their vector sum points to magnetic North (Fig 12-12). The simple one-spoke detector suffers from another limitation in that the value of H changes with magnetic latitude. This produces a change in the static flux linking the spoke, even though the heading may remain unchanged. This limitation is

Fig 12-11: Detector Unit and Transmission System -

schematic

Fig 12-12: Operation of the Three-spoke Fluxvalve

Fig 12-13: Eliminating Latitude Ambiguity

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overcome in the three-spoke fluxvalve because the flux associated with each spoke will change in proportion to the change in H. The resultant field across the receiver stator is still aligned with H (Fig 12-13).

22. In the three-spoke fluxvalve a single primary coil excites all six cores. If a single arm of the fluxvalve is considered, it will be apparent that the top and the bottom of the exciter coil have opposite polarity. The flux induced in the upper core of the spoke is equal and opposite to that induced in the lower core and this is exactly the effect produced by the primary windings in the simple fluxvalve. The three arms of the fluxvalve are wound with secondary or pick-off coils which are star connected. The exciter coil is fed with 400 Hz single-phase current so that each of the three pick-off coils has an emf at 800 Hz induced in it whose amplitude is proportional to the magnetic heading of the aircraft. Each core of the fluxvalve is fitted with a flux collector horn to concentrate the Earth's lines of force through the core. This increases the static flux and therefore the induced voltage.

The multi level inverter has been introduced since 1975 as alternative in high power and medium voltage situations. The Multi level inverter is like an inverter and it is used for industrial applications as alternative in high power and medium voltage situations.

Multilevel inverters are three types.

1.Diode clamped multilevel inverter

2.Flying capacitors multilevel inverter

3.Cascaded H- bridge multilevel inverter

Insane Clown Posse

A: To begin with the leads polarity of the meter must be ascertain. Assuming the red is positive voltage then that lead will have a positive potential to check a diode connect the red lead to the anode and the black to the cathode and it should read some Resistance

A: A DAC and ADC will have by design a certain assignment of bits or steps each step or bit value is dependent o the total number of bits available 12 bit dac assuming 10v reference its LSB value will be 4.08 mv minimum 10V/2048=4.08 mv

2048 is 2 raised 12 times

series

I'm not sure where you are getting your information. Capacitors come in a large range - nano farad to several farad. The higher the farads, the bigger (in general) the capacitor will be. For example, amazon has a 1 F, 20 volt cap for ~76.00. I would consider this to be "generally available in the market". If you want a 1 farad cap for 120 volts, it's going to be substantially bigger than this one (20 volt is ~5 lbs.).

Voltage is energy per charge, actually joules per coulomb, so think of voltage as electromotive force that pushes charge around. In fact, another name for voltage is electromotive force. Voltage is manifest as a differential energy between two points, where the energy "wants" to go from the higher energy point to the lower energy point. That is how voltage causes current.

Current is charge flow, actually coulombs per second, which is the same as the ampere.

Ohm's Law defines a unit of resistance called an ohm which is the resistance that one volt will require to push one ampere through. If you do dimensional analysis on the ohm, given the the ohm is the volt divided by the ampere, you discover that the ohm is actually a joule-second per coulomb squared - much easier to just call it an ohm.

Pushing coulombs from one energy level to another involves work. Multiply voltage by current, and you get watts, or joules per second.

Take some time to study this and understand it, and you are well on your way to a basic understanding of electricity 101. I know I answered more than was asked, but some of it was necessary in order to explain things, and the rest was just for the sake of completeness.