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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 difference between periodic and aperiodic real-time tasks?
A periodic real-time task is any task where there is a set amount of time allocated to a regularly repeated task whereas an aperiodic task is any task that occurs from a randomly occurring event.
What are the parameters of analog signal?
The parameters of analog signals are
1.Amplitude
2.Wavelegth
3.frequency
4.phase angle
Up to which frequency does the gain of an antenna increase as the frequency increases?
In general, an antenna is "cut" or "built" for one frequency, or for a band of frequencies centering on one particular frequency. This antenna will respond to all frequencies, but will only exhibit "maximum" gain at one frequency. Frequencies higher or lower will not be received quite as well, and the farther from the "tuned" or "center" frequency the signal is, the less gain the antenna will provide on that frequency. As we work with an omnidirectional antenna, we can "tinker" with it a bit in an attempt to get it to work with a broader range of frequencies, but as we broaden the usable spectrum over which it will work, we will see less gain on the "center" frequency. If you're getting the idea that tuning an antenna involves trade-offs, you're getting the right picture. No improvements are possible without "cost" in another part of the operating spectrum. If we move to a directional TV antenna like, say, one of those antennas (not the dish) that still can be seen on some rooftops, we see what is basically a modified log periodic antenna. This antenna will generally be "pointed" or "aimed" in the general direction of the transmission antenna of the station(s) for which reception is desired. Stations with broadcast antennas to the side or the rear of this antenna won't be "seen" as the antenna is highly directional. Having said all that to get you up to speed on some fundamental concepts of the antenna, as we move up the frequency spectrum (starting "low"), the gain of the antenna will increase until we reach the "center" or the "tuned" frequency for that antenna. After that, increasing the frequency will result in signals with increasingly lower gain.
How do you read the value of a ceramic capacitor?
Most ceramic capacitors use a numbering scheme similar to the resistor color code. Usually, three numbers are given.
The first two numbers are significant figures, and the third is the base 10 multiplier, or number of zeroes to add onto the end.
With ceramic capacitors, the value you get is typically assumed to be in picofarads (pF, 10-12 Farads). For much larger capacitors, the value is sometimes given in micro-Farads (uF, 10-6 Farads).
For example, for a capacitor marked "154":
1: First sig. fig
5: Second sig. fig
4: multiply by 104 (add 4 zeroes)
Result: 150,000 pF
Now, you can divide by one million to get an answer in uF, if that is more comfortable for you to work with:
150,000 pF = 0.15 uF
Therefore, a capacitor marked 154 has a value of 0.15 uF.
This should get you started reading ceramic capacitor values. For more detail, see the "coding" section of the wikipedia article on ceramic capacitors.
How can you build an electronic controlled timer for a deer feeder?
The easiest approach is to use a 555 timer. See the related links to learn all about the 555. Then build one of their circuits, and adjust the two resistor values (connected to pins 6 and 7, and then 7 to 8.) and adjust the capacitor until you get the timing you want. The ratio of the resistor values is the ratio the output will be high then low. This is called the "Duty Cycle". In your case, you want to generally have a 9:1 ratio, because you want to detect when a certain amount of time has passed. So one resistor value must be 9 times the other one. To calculate the approximate waiting time, just take the larger resistor value and multiply it by the capacitor value. To calculate the approximate "active time", take the lower resistor value and multiply it by the capacitor value. "active time" occurs when the desired amount of time is over. This "active time" period lasts for a short while then the process starts all over again. To sum up, Experimenting with the 555 timer is your best answer. It depends on the resources available and the extent of control desired, acceptable cost, whether or not solar panels or other power sources are available, etc. Option 1. Analog approach, based on timer ICs such as the venerable 555. Advantages: simple circuits. Disadvantages: long delay times between feedings require expensive components for acceptable accuracy, temperature swings can drastically affect timing. Option 2. Analog approach with sensors, using a light sensor to detect dawn/dusk and one-shots to time feed dispensing. Advantages: more appropriate operation times. Disadvantages: circuit complexity and sensor placement, possibility of false triggers (clouds, trees, or animals affecting sensors). Option 3. Analog plus digital approach, based on a timer IC or crystal oscillator and digital dividers. Advantages: better timer accuracy. Disadvantages: circuit complexity. Option 4. All-digital approach, based on microcontroller with crystal oscillator. Advantages: better timer accuracy, fully programmable feeding times and dispensing. Disadvantages: circuit complexity, programming required. Option 5. CPU approach, based on industrial computer with cellular modem interface, possibly with camera(s). Advantages: remotely user-controlled, monitorable. Disadvantages: circuit complexity, power requirements, geekiness. By all means use the lm555 timer plenty of design ideas on the Internet The only variation i will add to the timer is a trigger where by it will begin timing as the deer approach the feeder. The time for the feed can then set by you as desired time. just one lm555 will do it. or install a computer camera and what not to replace it. If you listen to these fellows first thing you know you are using a $300 a computer power supplies and what not. The sign of a good engineer is the guy that solve problems as efficiently as possible. A $ 5.00 ac mechanical timer good for 24 hour provide ac output to an electrical device to open or close a flap. run an ac motor your choice.
Why low pass RC circuit can not alter the shape of the sinusoidal signal?
because it is an alternating wave and it has no dc value on it.In RC circuit the capacitor blocks only dc values and it allows all ac values so the wave shape is preserved
To solve for resistors in parallel take the inverse of the sum of the inverses of all the resistors: 1/((1/r1) + (1/r2) + (1/r3)...)
[Google this. It is a lot easier to understand when the proper notation can be drawn.] SO: Rt = 1/((1/70) + (1/30)) = 21ohms
The image shows the first integrated circuit. It was handmade by Jack Kilby at Texas Instruments in 1958 using a bar of germanium in which he formed transistors and resistors by diffusion then wired these components into a circuit by hand.
Radio signals have several characteristics ... wavelength, field strength, amplitude, advertising cost,
popularity, frequency, etc. The question doesn't specify which characteristic it wants measured in order
to name the "highest" and "lowest".
We'll assume it's referring to the frequency of the various radio signals.
In the USA, commercial AM broadcast stations all have carrier frequencies between 0.55 MHz and 1.7 MHz.
Typical consumer AM radios are designed to operate across that range.
In the USA, commercial FM broadcast stations all have carrier frequencies between 88 MHz and 108 MHz.
Typical consumer FM radios are designed to operate across that range.
When building a bridge rectifier how do you choose the right size diode?
By figuring out how much amperage you wish to pass through the diode. If for instance you are building a battery charger and the transformer would normally supply 10 amps, you would select a diode (or diodes in parallel) that would handle at least 10 amps. You would normally select diodes that are at least 125% of the current desired. In this example you would select a diode that would handle at least 12.25 amps. It is better to use a rating of 150% for a safety margin.
A: A silicon bar basically can pass current but if a voltage of the right potential is applied it constrict the flow. basically that is it.
Further Explanation:
A MOSFET (metal oxide semiconductor field effect transistor) is composed of three doped regions - two N type and one P type or vice versa.
When a voltage is applied to the gate (the single P type in NPN, or N type in PNP), this causes a path to be created in the gate material. If the gate material is P type, a positive voltage will cause electrons to concentrate near the gate terminal. This concentration of electrons acts as a wire between the two N type materials. As more voltage is applied, the voltage gradient across the P type material will increase (to a point), resulting in a larger virtual "wire" of electrons. A PNP type transistor operates in a similar fashion.
What happens to the flow of electricity in an incomplete circuit?
It stops flowing. An analogy to this is the kitchen faucet ... water is always "at the ready" behind the valve, ready to flow when it is enabled. Same is true in an electrical circuit - once the circuit is broken (valve closed in above analogy) the flow of electrons ceases.
If there is a light bulb which is not on it is a open circuit. If the light bulb is still on it is parallel circuit which has lot of wires causes some of the lights to go on and some to go of.
What two types antenna used for terrestrial microwave communication?
Virtually all terrestrial microwave communication is point-to-point,
using parabolic reflector antennas.
A small percentage uses yagi, helical, corner reflector, or flat-plate reflector antennas.
Essentially no "omnidirectional" antennas are used in microwave.
What is Opto Mechanical Instrument?
If you are referring to an optometrist Opto Map....then it is a machine that takes a picture of your retina so the doctor can look at 200 degrees of the inside of your eye
Which is most dangerous between high capacitance and high voltage regarding capacitors?
As from a human contact perspective:
High voltage alone poses not much of a danger if the current is very low. It may be rather uncomfortable but a normal healthy person with no heart disorder should not be endangered with high voltage and very low current.
Low voltage capable of high current poses not much of a threat to humans either as long as our skin is dry.
The combination of High voltage capable of high current is deadly to most humans.
A capacitor of high capacitance is normally a low voltage one.
High voltage is normally found only in very low capacitances.
Which of them that are most dangerous is a bit difficult to answer without more information.
A high capacitance capacitor with low voltage may explode violently when connected to high voltage source capable of high current. This is very dangerous. Although not killingly dangerous, you can easily loose an eye or two.
A high voltage capacitor is not likely to explode due to high voltage. The current it carries when charged can be rather uncomfortable but not likely dangerous as in life threatning. This because the leads are so close together (current would need to go across heart in order to cause lethal problems in normal healthy people) so unless you force yourself to hold one lead with one hand and then touches the other lead, then it poses as no particular threat. Even if doing that, the current carried by the capacitor is not likely to be able to cause heart to stop. It might make a jump though.
I would place my bet on High Capacitance due to the danger of explosion.
Be sensible when experimenting with electronics, and you should not need to think about this :-)
What is arithmetic to geometric mean?
You can see the difference in the following link: "Calculation of the geometric mean of two numbers".
There's no reason for the capacitor to heat up, because it's only storing energy,
not dissipating it. When you discharge the capacitor, the energy flows out and
through the external circuit, and that's where it dissipates. If anything is going to
melt or explode, it's going to be something outside of the capacitor, through which
you try to jam the energy.
Which brings us to the 1-ohm resistor . . .
You have said that you have a "450V" capacitor. The rating marked on a capacitor
isn't the voltage across it when it's charged ... that can be whatever you make it.
The marking is the maximum that the capacitor can hold without arcing across
between the plates ... the number is called the "maximum working voltage".
You can try to charge a capacitor to whatever voltage you want, but it won't
hold any more than the number marked on it.
In order to discuss the fate of that 1-ohm resistor, we have to know what the
initial charge is on the capacitor. The only number given in the question is 450V,
and even though that's more likely the "max working voltage" of the capacitor,
let's assume for the moment that the capacitor is actually charged up to 450 volts DC.
The charging is complete, the staff retreats behind their bullet-proof plexiglass
bunker, puts on their dark glasses, and prepares to push the button that will
remotely close the circuit and discharge the capacitor through the 1-ohm
resistor. The button is pushed, and here's what the high-speed camera reveals
after the smoke clears and the fire units have departed:
As the energy drains from the capacitor, the voltage on it steadily dwindles.
How fast it dwindles depends on the resistance of the external circuit, and on
the "capacitance" of the capacitor (which tells us how much energy it takes to
charge it up to any given voltage).
What we do know about this circuit is that the capacitor is charged initially to
450 volts, and that it discharges through 1 ohm. This is enough for us to
calculate the initial current at the instant the switch is closed ...
I = (450 volts)/(1 ohm) = 450 Amps.
We can also calculate the power dissipated by the resistor at that instant:
P = I2 R = (450)2 x 1 = 202.5 kilowatts ... roughly the power that would be
demanded of a car battery if it had to start 85 cars all at the same time!
Regardless of the capacitance, and how quickly the charge on the capacitor
dwindles down from 450 volts, it's likely that this initial surge through the
1-ohm resistor causes it to self-destruct like a pellet of plutonium on the
tower at White Sands.
To answer the question:
Your capacitor is safe from harm. But if you're going to discharge it through 1 ohm,
then please wear gloves, safety glasses, and a kevlar apron.
What is photo sensitive diode and how it works?
A diode that is sensitive to light. As light increases, the diode resistance drops. This can be used as a sensor in control circuitry that directs solar panels so they are always facing the sun. They also can be used to automatically turn on street lights, garden lights, among many other applications.
Does resistance use amps or voltage?
Resistance doesn't "use" either. Resistance is the division of voltage by current. It can be though of as a measure of how hard it is to push electrons through a substance.
What is the purpose of a phase-shift network in a Wien bridge oscillator?
A Wien bridge oscillator produces sine waves. In order for the sine waves to maintain a steady amplitude, a positive feedback system is used with some sort of control to limit gain. In order for the positive feedback system to work, the waves being "fed back" to the amplifier have to be in phase with the waves being generated. Thus, you need a phase shift network to ensure that the phases of the waves match, which in the case of a positive feedback system means that the generated waves need to go through a 360o phase shift during the feedback process.
What is Voltage drop compensation?
A; The best way to describe is this way the load requires 10 volts but due to wiring and bad connections it gets to be 9v 1 volt is lost on IR drop so to compensate the input voltage needs to be boost up to 11 volts to insure 10 volts across the load
How do you make artificial electromagnetic radiation with a coil?
What you want to build is a radio transmitter. It takes a bit more than just a coil, however you might try looking up "spark gap radio transmitter" as it is very simple and was the first type of radio transmitter built. Basically it transmits bursts of radio static.
