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Electronics Engineering
Electronics Engineering is a branch of engineering that deals with practical applications of electronic components, devices, systems, or equipment. Electronics are devices that operate on low voltage sources, as in electron tubes, transistors, integrated circuits, and printed circuit boards and use electricity as part of its driving force.
24,372 Questions
What is the resistance of a power cord?
It depends on the size of the cord and the volts it carries-
But to find how much VOLTAGE a wire consumes...
It could be found by V = I X R
Usually the resistance of electrical wires is not TOO important- its important when you try to force large amounts of current through a long piece of wire. So lets say a wire is very long and was connected to a battery that had 15 volts and the resistance of the thin wire is 0.2, V=15 x 0.2 = 3 volts. Three volts is not a big deal if you have a high voltage power supply, but if you are using say a 12 volt car battery the length of the wire would take one quarter of the available voltage-which is why a automotive batteries cable is thick -to reduce its resistance below 0.2Ohms.
This is still sort of an in-direct answer- but it might help.
What is the maximum resistance you want to see across a switch?
The maximum resistance across a switch should be infinite.
What are the key differences between academic and casual communication styles?
The difference between academic and casual communication. Casual communication is more of socializing with family and friends and co-workers and academic is speaking in a more professional manner. Adhering more to the words and the proper language use. You would not normally speak in a professional manner on a daily basis unless you are in a professional surrounding 24/7.
What is the role of pnp and military?
PNP Positive Negative Positive, is a type of Transistor. I don"t know of military applications.
On a silicon-controlled rectifier which wire is the anode and which the cathode?
Anode is positive, cathode is negative
Because in radio communication a signal is specified by its frequency, In AM the carrier frequency is fixed.. we cant limit or manipulate it as it will might switch us to another carrier in the atmosphere... manipulating however amplitude (as in FM) doesn't switch us to another channel... so remember in radio communication signal is specified by its frequency whether FM or AM..
2 transistor analogy for scr and derivation for expression of anode current?
a thyristor can be considered as two complementary transistors , one pnp- transistor, and other npn transistor
What is the significance of knee voltage?
A PN junction diode is a non-linear component and it consists of two junctions namely P-junction & N-junction where the majority and minority charge carriers are present like electrons and holes. It is also known as a semiconductor diode or PN junction diode. This diode includes two terminals namely anode and cathode, where a p-type semiconductor is an anode (positive voltage) and N-type semiconductors are cathode (negative voltage). The flow of current in the diode is in one direction only because it opposes in another direction with high resistance.
What is flux valve and its operation?
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.
75 Radio Magnetic Compass
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
FIS Book 4: Instruments 76
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
What does a 556 timer chip do?
A: this chip is defined as a timer but it can be used for other reasons and applications.
Do transistors follow ohm's law?
As transistors are made of semiconductors, they do notfollow Ohm's law.
A: they cannot follow exactly ohms law since they are themselves no linear active devices
Why a bird not die when sat on a dual transmission line?
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
How do you calculate power loss from a resistor?
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.
How do you test polarity with a multimeter?
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
Is the output impedance of common emitter a fixed quantity?
A: NO it is not fixed it depends on the load line
ONE low pass(RC) circuit gives 60 degrees phase shift
What happens to an LED When the voltage is to high?
when a LED is subjected to a high voltage it will heat up and burn the internal junction, which will leave the LED open circuit.
What does hPa means in terms of pressure in weather?
hPa stands for Hectopascal preasure unit this is the international unit for measuring atmospheric or barometric pressure.
1 hPa = 100 pascals
Standard atmospheric pressure = 101325 pascals = 1013.25 hPa
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
Rx level is the measure of power what we get at the recieving end.
Rx level value is different for every different application
e.g In microwave link it is between -30dBm to -60dBm n this is planned accordingly.
whereas the RSL of a GSM handset of the GSM antenna (BTS End) is between -70dBm to -120 dBm or something like this value where the GSM system operates
this value is the measure of power so, this value should be there or this is the operating ranges in different different applications.
another word is Rx Quality this is the other name for BER i.e Bit Error Rate, so BER defines the Rx quality. it means that lower the %ge of BER better the Rx quality.
thanx
Why 1 farad capacitor generally is not available in the market?
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.).
