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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 allows the flow of electrons?
Whatever power source is driving them. If a battery, then chemical energy from the battery chemicals. If a hydroelectric turbine, then potential energy from the waterfall.
it is the power ratio in decibels
No, it isn't. dB on its own is a ratio.
But when dB has a suffix, the figure is an absolute measurement, not a ratio.
For instance, dBm is a measurement of power compared to 1mW.
0dBm means zero difference between 1mW and the measured figure. In other words the measured figure is also 1mW.
3dBm is 3dB greater than 1mW. -3dB is 3dB less than 1mW. etc.
Another suffix is W. 0dBW being 1 watt.
There are many more suffixes, some of which are used in only a few specialised cases.
How does the capacitance change if the voltage across the capacitor is doubled?
As capacitance is not affected by voltage, nothing will happen! Capacitance is affected only by the area of overlap of the plates, their distance apart, and the permittivity of the dielectric.
When was first printed circuit board developed?
Related Photo: http://www.makingthemodernworld.org.uk/icons_of_invention/img/IM.1201_el.jpg This radio is the first working device to use a printed circuit board (PCB), the electronic technology invented by Paul Eisler. An Austrian refugee in London, Eisler made this radio in 1942, following on from initial experiments in 1936. At the time, it was usual to interconnect all components in electronic goods with hand-soldered wires, a method of manufacture which did not lend itself to any high degree of automation. First applied in proximity fuses for anti-aircraft missiles, PCBs have subsequently found near universal application in electronic goods, yielding highly miniaturised devices which can be mass produced.
What is the difference between a circuit board and an intergrated circuit?
A cicuit board is a board made of plastic and metal interconnections where the various electronic devices are assembled in discrete form to make up the circuit.In an integrated circuit a semiconductor chip is so processed such that the various electronic devices and components are directly grown on it.
What is the effect of carrier frequency variation on AM signal?
If the modulation is to large your bandwidth will be to wide in other words the frequency shift will be larger than normal that will result in a distorted audio signal at the receiver
What are the disadvantages of DSB-fC modulation?
- in DSB-SC since carrier is suppressed,hence power consumption is reduced and nominal.
- The power in the modulated signal is contained in all four sidebands.
- The bandwidth of the DSB-SC signal is double that of the message signal, that is, BWDSB-SC =2B (Hz).
How many sidebands? There's only two; upper and lower.
Why is an ammeter is always connected in series with the circuit?
When considering electricity,
Current (measured in Amps) is often considered the flow of energy.
The force behind the flow is the Volts.
While the volts can be measured between any two points in the circuit (open, or closed), measuring the current, or flow of energy typically requires interrupting the flow.
Somewhat like water. One can measure pressure of the water on a branch, but one must have a way to monitor the actual flow to determine how much water has passed.
There are "exceptions" though.
If you have an AC circuit, then an inductive ammeter can measure the amps around a single leg if the circuit without being installed inline with the circuit.
Even with a DC circuit, it may be desirable to design a bypass or shunt circuit so that the majority of the current bypasses the ammeter, and only a small amount of the current actually flows through the ammeter.
What is best describes how a varactor diode modulator creates FM?
Resonant frequency of a circuit is proportional to sq rt (L x C). A varactor diode, when suitably voltage biased, looks like a capacitor (C). Varying the bias varies the capacitor and thus the resonant frequency .
Does the capacity of the battery increase when they are connected in series?
No. If you connect in series, positive to negative and then connect load to the remaining positive and negative terminals then the voltage at these terminals is the added voltage of the batteries thus connected, but the capacity (amphours) stays the same.
How do you find the forward voltage of a diode?
A Transistor can be biassed in two ways Forward bias and Reverse bias A transistor is said to be forward bias if the positive of the transistor is connected to the positive terminal of the battery and negative to the negative terminal of the battery.A Transistor in the converse condition is known as reverse biassed
What is counter and register in electronics?
Counter is a digital circuit which is able to count from a specific number to another specific number (according to the requirement). Depending upon the counting style the counters can be divided into two.
i) UP counter- which increment one by one (eg. 0,1,,2,3,4,5............15) for a 4 bit counter
ii) Down counter- which decrements one by one (eg. 15,14,13,12,11,10,9,8................0) for a 4 bit counter.
A simple apllication of a counter is a diigital clock, having 3 counters. One for counting the seconds, another for counting the minute and the last one for counting the hour.
Full subtractor using 2 half subtractor?
The half adder is an example of a simple, functional digital circuit built from two logic gates. A half adder adds two one-bit binary numbers A and B. It has two outputs, S and C (the value theoretically carried on to the next addition); the final sum is 2C + S.
What is the application of TTL in integrated circuits?
Transistor transistor logic is one type of many different types of bipolar transistor based digital logic circuitry. It is very efficiently implemented in integrated circuit chips, needs only one power supply voltage, and operates at reasonably high speeds.
Transistor transistor logic was first developed in the middle 1960s as a modification of the diode transistor logic, then in use in some digital logic integrated circuit chips but dating back to the earliest discrete bipolar transistor logic developed in the late 1950s and derived from vacuum tube point contact diode logic used in many early first generation computers.
Transistor transistor logic integrated circuits dominated the computer and electronic digital controller market from the late 1960s until the middle 1980s, when metal oxide semiconductor field effect transistor based microprocessors and microcontrollers began to replace it. By the early 1990s transistor transistor logic and other bipolar transistor based digital logic integrated circuits had been replaced with equivalent complementary metal oxide semiconductor field effect transistor integrated circuits that were both faster and consumed less power (thus running much cooler) or with programmable logic devices of various types.
In general transistor transistor logic is now considered obsolete.
Non-zero initial condition is called DC offset. DC offset is bad, and needs to be removed by HP filter as they cause distortion, non-linearity.
If the mean/average amplitude of the wave is zero it has no DC-offset.
Why current doesn't flow when negative voltage is applied to diode?
A normal (non zener) diode only conducts in one direction, when the anode is more positive than the cathode. This is called forward bias, and it occurs between 0.6 and 1.4 volts, depending on the specification of the diode.
In the reverse bias condition, with the cathode more positive than the anode, the diode does not conduct, except for minor leakage current, until it reaches its breakdown voltage. At that point, normal diodes1, unless current limited, will self-destruct. The reverse breakdown voltage is usually much more than the forward bias voltage, typically hundreds or thousands of volts reverse compared to around one volt forward. As a result, diodes, as used in rectifier circuits, will only conduct on the positive half-cycle of AC power.
If you want conduction in both directions, in a rectifier, you need two diodes and a center tapped transformer, or four diodes in a bridge configuration (one phase; six diodes for three phase) in order to conduct on every half line cycle.
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1Zener diodes, on the other hand are designed to conduct in a controlled fashion in the reverse bias condition due to PN junction doping that allows reverse breakdown without destruction. Zener diodes are used in regulator circuits.
Yes. Ohm's law is generally thought of as a basic law of electricity, but electricity is, in the language of physics, a part of the electromagnetic force. The electromagnetic force is one of the four basic forces in the universe (allong with gravity, the strong force (called the strong interaction) and the weak force (called the weak interaction). That's the electromagneticforce. Not the electric force or the magnetic force, but the electromagnetic force. And Ohm's law is a most fundamental expression of the relationship of voltage, resistance and current in an electrical circuit. In that light, Ohm's law is a general law of the electromagnetic force. Note: Some science teachers might try to split hairs here and say that Ohm's law is an electrical law and not an electromagnetic law, but this is one of those questions that might be said to have two answers. As regards what was said in the first paragraph, nothing in it is incorrect. Nothing at all.
Another Answer
Absolutely NOT! For Ohm's Law to be valid, the ratio of a circuit's voltage to current must be constant for variations in voltage. In other words, if you were to plot current against voltage for variations in voltage, you should end up with a straight-line graph. In fact, this is rarely the case. In most cases, you will end up with a curved line which confirms Ohm's Law does NOT apply.
Most materials and electronic devices (diodes, etc.) are classified as being 'non linear' or 'non-ohmic', meaning they DO NOT OBEY OHM'S LAW.
So Ohm's Law is most certainly NOT a universal law and, in fact, barely qualifies as being a law at all!
Why the name pushpull is given to pushpull amplifier?
Because first one side of the amplifier pushes on one half cycle then the other side of the amplifier pulls on the other half of the cycle.
If resistance equals 5 ohm and voltage equals 6v then find current?
Ohms Law! E=IR Voltage equals current times resistance. Get out the old calculator...
Why did transistors eventually replace valves in radios?
"Valve" is the British word for Vacuum Tube, so for the British (which the person asking this question probably is) transistors did replace valves. Therefore the answer remains that values(vacuum tubes) where large and bulky, in addition they require high levels of power to function and created substantial heat and were quite fragile. The creation of the Transistor and then micro chip allowed for portability, lower levels of operation power to be required and reduced costs due to mass production
What company developed the transistor?
Julius Edgar Lilienfeld, 1925.
John Bardeen and Walter Brattain, 1947, AT&T
Can you change a 440 volt 12.5 uF start capacitor with a 370 volt 12.5uF run capacitor?
There are two ways to read this: you have a burned-out run capacitor on your motor and a good start capacitor in your parts box, and you have a burned-out start capacitor and a good run capacitor. If the run capacitor's bad and you want to put the higher-voltage start cap in its place, the answer is yes. This is called derating, and the only thing it does for you is increases the lifespan of the capacitor because you're not working it as hard as it can take. If the start capacitor's bad, don't do this--they used a 440-volt capacitor in there for a reason.
