Basic Laws Of Electronics
Thanks to the physical laws of electronics, circuit analysis is very procedural. This is the second entry in a tutorial in basic electronics. The first entry covered basic electronic concepts such as voltage, current, and power. This session will cover Ohm’s Law, and Kirchhoff’s Laws of voltage and current. These are the fundamental laws needed for circuit analysis and design.
Resistors and Ohm’s Law
Georg Simon Ohm was a German physicist that in 1826 experimentally determined most basic laws that relate to voltage and current for a resistor.
Ohm’s law basically states that the resistance of a component (commonly a resistor) is equal to the voltage dropped over the resistor divided by the current going through it.
This law makes it relatively easy to find one of three values: voltage across a resistance, the resistance value itself, or the current flowing through the resistance (as long as the other two values are known).
Nodes, Branches, and Loops
These three concepts must be understood for basic circuit analysis. They help determine if components are in series or parallel and if the components share the same current or have the same voltage drops.
A branch represents a single circuit component such as a resistor or voltage source.
A node is a point where two or more branches connect.
A loop is any closed path in a circuit.
Elements are in series if they exclusively share a single node. Elements that are in series share the same current.
Elements are in parallel if they are connected to the same two nodes. Elements in parallel have the same voltage across them.
Kirchhoff’s Laws
The first of Kirchhoff’s Laws is Kirchhoff’s current law (KCL). This law states that the sum of all current entering a node or enclosed area of a circuit is equal to zero. Simply put, current entering a node or area equals the current leaving the node or area.
The second of Kirchhoff’s Laws is Kirchhoff’s voltage law (KVL). This law states that the sum of all voltages around a closed path or loop is equal to zero. Simply put, the sum of voltage drops equals the sum of voltage rises.
This is found by following the loop in one direction (the direction does not matter). If the positive terminal is hit first, the voltage is added. If the negative terminal is hit first, the voltage is subtracted. Together these values will equal zero.
Once all of the voltages are found, we can start the loop anywhere we want. I find it convenient to start at the negative terminal of a main voltage source. Since we hit a negative terminal first, we subtract it. Now we simply finish the loop and add the voltages together.
This law comes in very handy for analysis.
Basic DC Analysis
By combining Kirchhoff’s voltage and current laws, basic DC circuits are relatively easy to analyze. Knowing that all voltages in a loop add up to zero and all currents entering a node, minus currents leaving a node also equals zero, most current and voltage values can be easily obtained.
If a loop contains one voltage source and multiple resistances, voltage division (eq. 1) should be used to find the value of voltage drops across the known resistances. Once the voltage across the known resistance is found, Ohm’s law (eq. 2) can be used to determine the current flowing through the resistance.
Eq.1 Voltage Division:
((voltage source in volts) (resistor of interest in ohms))/(sum of resistance in loop)
Eq.2 Ohm’s Law:
(voltage across a resistance) = (known resistance)(current flowing through resistance)
Keep in mind that resistors in series can be added to give total resistance between two nodes. The total resistance between two nodes that have resistors in parallel is found using eq. 3 below.
Eq. 3 Equivalent Resistance (Req) of Resistors in parallel:
Req = ((resistance in branch 1)(resistance in branch 2)) / (sum of resistances in both branches)
There is much more to be said about DC circuit analysis but most would go beyond the scope of this article. The purpose of this article is to give a basic understanding of the laws and concepts of basic electronics.
Other concepts that make DC circuit analysis easier are current division, mesh analysis, and nodal analysis. These techniques use the rules behind KVL, KCL, and Ohm’s Law but would require a visual example for thorough explanation.
I hope that this short tutorial has been helpful to anyone who is new to the world of electronics either as a hobbyist or as a technician trying to learn electronics repair.
Radio Controlled Helicopters
Radio controlled helicopters (also RC helicopters) are model aircraft which are distinct from RC airplanes because of the differences in construction, aerodynamics, and flight training. Several basic designs of RC helicopters exist, of which some (such as those with collective pitch, meaning blades which rotate on their longitudinal axis to vary or reverse lift) are more maneuverable than others. The more maneuverable designs are often harder to fly, but benefit from greater aerobatic capabilities. Flight controls allow pilots to control the collective and throttle (usually linked together), the cyclic controls (pitch and roll), and the tail rotor (yaw). Controlling these in unison enables the helicopter to perform most of the same maneuvres as full sized helicopters, such as hovering and backwards flight, and many that full sized helicopters cannot.
The various helicopter controls are effected by means of small servo motors, commonly known as servos. A piezoelectric gyroscope is typically used on the tail rotor (yaw) control to counter wind- and torque reaction induced tail movement. This gyro does not itself apply a mechanical force, but electronically adjusts the control signal to the tail rotor servo. The engines typically used to be methanol-powered two-stroke motors, but electric brushless motors combined with a high performance lithium polymer battery (or lipo) are now more common and provide improved efficiency, performance and lifespan compared to brushed motors, while decreasing prices bring them within reach of hobbyists. Gasoline and jet turbine engines are also used.
Common power sources are nitro (nitromethane methanol internal combustion), electric batteries, gas turbines, petrol and gasoline. Mechanical layouts include cyclic/collective pitch mixing (CCPM) in all power sources, fixed pitch electric rotors and coaxial electric rotors. Practical electric helicopters are a recent development but have rapidly developed and become more common, overtaking nitro helicopters in common use. Gas turbine helicopters are also increasing in popularity, although the high cost puts them out of reach of most people.
Nitro or glow fuel helicopters come in different sizes: 15, 30, 50, 60 and 90 size. These numbers originated from the size of engine used in the different models (0.30 cu in, 0.50 cu in and so on). The bigger and more powerful the engine, the larger the main rotor blade that it can turn and hence the bigger the aircraft overall. Typical flight times for nitro helicopters is 7-14 minutes depending on the engine size and tuning. The maximum height of operation for RC helicopters, be it nitro or electric, is only limited to the height at which the controller can see the model. Most radio systems have a range of over a mile, and the person controlling the model will have long lost sight of the model.
Two small electric helicopters emerged in the mid 1990s. These were the Kalt Whisper and the Kyosho EP Concept, flying on 7/8 1200 mah NiCad batteries with brushed motors. However, the 540 brushed sized motors were on the limit of current draw, often 20-25 amps on the `hotter’ motors, hence brush and commutator problems were common. S107 metal series Recent advancements in battery technology are making electric flying more feasible in terms of flying time. Lithium polymer (LiPo) batteries are able to provide the high current required for high performance aerobatics while still remaining very light. Typical flight times are 4-12 minutes depending on the flying style and battery capacity.
Small fixed pitch helicopters need a 4-channel radio (throttle, elevator, aileron, rudder), although micro helicopters that utilize a 2-channel infrared control system also exist; while collective pitch models need a minimum of 5 channels with 6 being most common (throttle, collective pitch, elevator, aileron, rudder and gyro gain). Because of the normal interaction of the various control mechanisms, advanced radios include adjustable mixing functions, such as throttle/collective and throttle/rudder. RC Helicopters usually have at least four controls: Roll Cyclic Pitch, Elevator (Fore Aft Cyclic Pitch), Rudder (Yaw) and Pitch/Throttle (Collective Pitch/Power).
[Top]See How Much Long Your Electronics Will Last With A Skin
IPhones are generally one of the most in-demand cellphones you can get now due to their gigantic variety connected with apps as well as customizations. The item carries turned out to be an important style device ought to have got. One means to make it actually more custom-made along with additional distinctive to you, is by simply employing iPhone 4 skins. These kinds of skins are usually defensive cases that will fit comfortably on to the new iPhone 4 which not just can make this appear unique however, furthermore shields the cell phone from scuff marks as well as accidents.
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[Top]Leading Electronics Makers Samsung And Lg Shift Focus To Fast-growing Lcd & Led Televisions
New Delhi: Remember toy major Leo Mattel being forced to withdraw Barbie dolls from the global market because they were coated with paint containing dangerous levels of lead? The Indian government is keen to similarly empower consumers against sub-standard goods. In the works are a set of tough laws which will include the critical product liability clause, making erring manufacturers and suppliers liable to pay punitive damages.
The proposals, expected to substantially overhaul existing consumer electronics goods manufacturers
Electronics gadgets Questions How To Choose A Portable Computer
There’s evidently a strain in a daily existence that does not involve electronic gadgets. Since contraptions make your life less complicated and more convenient, it’s vital to select your gadgets well. One of the basic prerequisites re gadgets is a lightweight computer. For that, you will select between a tablet and a laptop. But before making your call, hear out first what the differences between these 2 are. Otherwise, you would be simply wasting your money.
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Overall, selecting between a tablet and a portable computer truly is dependent on the functionality that you would like to take advantage of and naturally, the price that you’re prepared to pay for these electronic gadgets. Knowing these, it won’t be too hard finding which is best for you.
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