|
Radio Controlled Model
A radio-controlled model (or RC model) is a model that is steerable with the use of radio control. All types of model vehicles have had RC systems installed in them, including ground vehicles, boats, planes, helicopters and even submarines and scale railway locomotives. History Radio control has been around since Nikola Tesla demonstrated a remote control boat in 1898. World War II saw increased development in radio control technology. The Luftwaffe used controllable winged bombs for targeting Allied ships. During the 1930s the Good brothers Bill and Walt pioneered vacuum tube based control units for R/C hobby use. Their "Guff" radio controlled plane is on display at the National Aerospace museum. Ed Lorenze published a design in Model Airplane News that was built by many hobbyists. Later, after WW2, in the late 1940s to mid 1950 many other R/C designs emerged and some were sold commercially, Berkeley's Super Aerotrol, was one such example. Originally simple 'on-off' s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mark/space Ratio
A duty cycle or power cycle is the fraction of one period in which a signal or system is active. Duty cycle is commonly expressed as a percentage or a ratio. A period is the time it takes for a signal to complete an on-and-off cycle. As a formula, a duty cycle (%) may be expressed as: :D = \frac \times 100\% Equally, a duty cycle (ratio) may be expressed as: :D = \frac where D is the duty cycle, PW is the pulse width (pulse active time), and T is the total period of the signal. Thus, a 60% duty cycle means the signal is on 60% of the time but off 40% of the time. The "on time" for a 60% duty cycle could be a fraction of a second, a day, or even a week, depending on the length of the period. Duty cycles can be used to describe the percent time of an active signal in an electrical device such as the power switch in a switching power supply or the firing of action potentials by a living system such as a neuron. The duty factor for periodic signal expresses the same notion, but ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystal Oscillator
A crystal oscillator is an electronic oscillator circuit that uses a piezoelectric crystal as a frequency-selective element. The oscillator frequency is often used to keep track of time, as in quartz wristwatches, to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers. The most common type of piezoelectric resonator used is a quartz crystal, so oscillator circuits incorporating them became known as crystal oscillators. However, other piezoelectricity materials including polycrystalline ceramics are used in similar circuits. A crystal oscillator relies on the slight change in shape of a quartz crystal under an electric field, a property known as inverse piezoelectricity. A voltage applied to the electrodes on the crystal causes it to change shape; when the voltage is removed, the crystal generates a small voltage as it elastically returns to its original shape. The quartz oscillates at a stable ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Citizens' Band Radio
Citizens band radio (also known as CB radio), used in many countries, is a land mobile radio system, a system allowing short-distance person-to-many persons bidirectional voice communication among individuals, using two way radios operating on 40 channels near 27 MHz (11 m) in the high frequency (a.k.a. shortwave) band. Citizens band is distinct from other personal radio service allocations such as FRS, GMRS, MURS, UHF CB and the Amateur Radio Service ( "ham" radio). In many countries, CB operation does not require a license, and (unlike amateur radio) it may be used for business or personal communications. Like many other land mobile radio services, multiple radios in a local area share a single frequency channel, but only one can transmit at a time. The radio is normally in receive mode to receive transmissions of other radios on the channel; when users want to talk they press a "push to talk" button on their radio, which turns on their transmitter. Users on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Regenerative Circuit
A regenerative circuit is an amplifier circuit that employs positive feedback (also known as regeneration or reaction). Some of the output of the amplifying device is applied back to its input so as to add to the input signal, increasing the amplification. One example is the Schmitt trigger (which is also known as a regenerative comparator), but the most common use of the term is in RF amplifiers, and especially regenerative receivers, to greatly increase the gain of a single amplifier stage. The regenerative receiver was invented in 1912 and patented in 1914US Patent 1113149A, Edwin H. Armstrong, Wireless receiving system', filed October 29, 1913, granted October 6, 1914 by American electrical engineer Edwin Armstrong when he was an undergraduate at Columbia University. It was widely used between 1915 and World War II. Advantages of regenerative receivers include increased sensitivity with modest hardware requirements, and increased selectivity because the Q of the tuned ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Escapement (radio Control)
Servos (also RC servos) are small, cheap, mass-produced servomotors or other actuators used for radio control and small-scale robotics. Most servos are rotary actuators although other types are available. Linear actuators are sometimes used, although it is more common to use a rotary actuator with a bellcrank and pushrod. Some types, originally used as sail winches for model yachting, can rotate continuously. Construction A typical servo consists of a small electric motor driving a train of reduction gears. A potentiometer is connected to the output shaft. Some simple electronics provide a closed-loop servomechanism. Operation The position of the output, measured by the potentiometer, is continually compared to the commanded position from the control (i.e., the radio control). Any difference gives rise to an error signal in the appropriate direction, which drives the electric motor either forwards or backwards, and moving the output shaft to the commanded position. When ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internal Combustion
An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is typically applied to pistons ( piston engine), turbine blades (gas turbine), a rotor (Wankel engine), or a nozzle ( jet engine). This force moves the component over a distance, transforming chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to. This replaced the external combustion engine for applications where the weight or size of an engine was more important. The first commercially successful internal combustion engine was created by Étienne Lenoir around 1860, and the first modern internal combustion engine, known a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Control Line
Control line (also called U-Control) is a simple and light way of controlling a flying model aircraft. The aircraft is connected to the operator by a pair of lines, attached to a handle, that work the elevator An elevator or lift is a wire rope, cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or deck (building), decks of a building, watercraft, ... of the model. This allows the model to be controlled in the Aircraft principal axes#Transverse axis (pitch), pitch axis. It is constrained to fly on the surface of a hemisphere by the control lines. The control lines are usually either stranded stainless steel cable or solid metal wires of anywhere from to . Sewing thread or braided fishing line may be used instead of wires, but air resistance is greater. A third line is sometimes used to control the engine throttle, and more lines may be added to control other functions. E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Round-the-pole Flying
Round-the-pole flying (RTP) is a form of flying model aircraft, in which the model is attached via a line from its wingtip or fuselage to a central support structure. Control signals can be passed to the model via wires alongside or integral with the attachment line. The operator can control the aircraft using a control console, situated outside the flying circle of the aircraft. Contrast this to control line flying where the pilot/operator stands at the centre of the flying circle and directly supports the aircraft. RTP can be used indoors or outdoors, though usually requires calm wind conditions if used outdoors. The power source for the model is usually an electric motor, since the power can be supplied via the line and heavy batteries need not be carried. This makes it particularly quiet, clean and suitable for indoor flying. Conventional engines can be used outdoors. The pole itself is usually a simple stand heavy enough to withstand the centrifugal forces on it. The head of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerobatic
Aerobatics is the practice of flying maneuvers involving aircraft attitudes that are not used in conventional passenger-carrying flights. The term is a portmanteau of "aerial" and "acrobatics". Aerobatics are performed in aeroplanes and gliders for training, recreation, entertainment, and sport. Additionally, some helicopters, such as the MBB Bo 105, are capable of limited aerobatic manoeuvres. An example of a fully aerobatic helicopter, capable of performing loops and rolls, is the Westland Lynx. Most aerobatic manoeuvres involve rotation of the aircraft about its longitudinal (roll) axis or lateral (pitch) axis. Other maneuvers, such as a spin, displace the aircraft about its vertical (yaw) axis. Manoeuvres are often combined to form a complete aerobatic sequence for entertainment or competition. Aerobatic flying requires a broader set of piloting skills and exposes the aircraft to greater structural stress than for normal flight. In some countries, the pilot must wear a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proportional Control
Proportional control, in engineering and process control, is a type of linear feedback control system in which a correction is applied to the controlled variable, and the size of the correction is proportional to the difference between the desired value ( setpoint, SP) and the measured value (process variable, PV). Two classic mechanical examples are the toilet bowl float proportioning valve and the fly-ball governor. The proportional control concept is more complex than an on–off control system such as a bi-metallic domestic thermostat, but simpler than a proportional–integral–derivative (PID) control system used in something like an automobile cruise control. On–off control will work where the overall system has a relatively long response time, but can result in instability if the system being controlled has a rapid response time. Proportional control overcomes this by modulating the output to the controlling device, such as a control valve at a level which avoids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.svg "Click for more on -> Crystal Oscillator")
