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:
Pulse-width modulation (PWM), also known as pulse-duration modulation (PDM) or pulse-length modulation (PLM), is any method of representing a signal as a rectangular wave with a varying duty cycle.
Radio-controlled cars, or RC cars for short, are miniature model cars, vans, buses, trucks or buggies that can be controlled from a distance using a specialized transmitter or remote. The term "RC" has been used to mean both "remote controlled" and "radio controlled". "Remote controlled" includes vehicles that are controlled by radio waves, infrared waves or a physical wire connection. RC cars are powered by one of the three energy sources—electricity, nitro fuel or petrol. Electric RC models are powered by small but powerful electric motors and rechargeable nickel-cadmium (Ni-Cd), nickel metal hydride(NiMH), or lithium polymer (LiPo) cells with the former two being the most used. Both NiMH and LiPo have advantages and disadvantages in various RC applications where NiMH is mainly used for recreational and LiPo for more demanding purposes. There are also brushed or brushless electric motors—brushless motors are more powerful, long lasting and efficient, but also much more expensive than brushed motors.
A radio-controlled model is a model that is steerable with the use of radio control (RC). 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.
Pulse-position modulation (PPM) is a form of signal modulation in which M message bits are encoded by transmitting a single pulse in one of possible required time shifts. This is repeated every T seconds, such that the transmitted bit rate is bits per second. It is primarily useful for optical communications systems, which tend to have little or no multipath interference.
A power inverter, inverter, or invertor is a power electronic device or circuitry that changes direct current (DC) to alternating current (AC). The resulting AC frequency obtained depends on the particular device employed. Inverters do the opposite of rectifiers which were originally large electromechanical devices converting AC to DC.
In mechanical and control engineering, a servomechanism is a control system for the position and its time derivatives, such as velocity, of a mechanical system. It often includes a servomotor, and uses closed-loop control to reduce steady-state error and improve dynamic response. In closed-loop control, error-sensing negative feedback is used to correct the action of the mechanism. In displacement-controlled applications, it usually includes a built-in encoder or other position feedback mechanism to ensure the output is achieving the desired effect. Following a specified motion trajectory is called servoing, where "servo" is used as a verb. The servo prefix originates from the Latin word servus meaning slave.
Fan control is the management of the rotational speed of an electric fan. In computers, various types of computer fans are used to provide adequate cooling, and different fan control mechanisms balance their cooling capacities and noise they generate. This is commonly accomplished by the motherboards having hardware monitoring circuitry, which can be configured by the end-user through BIOS or other software to perform fan control.
Power electronics is the application of electronics to the control and conversion of electric power.
In electronics, a chopper circuit is any of numerous types of electronic switching devices and circuits used in power control and signal applications. A chopper is a device that converts fixed DC input to a variable DC output voltage directly. Essentially, a chopper is an electronic switch that is used to interrupt one signal under the control of another.
A variable-frequency drive is a type of AC motor drive that controls speed and torque by varying the frequency of the input electricity. Depending on its topology, it controls the associated voltage or current variation.
A class-D amplifier or switching amplifier is an electronic amplifier in which the amplifying devices operate as electronic switches, and not as linear gain devices as in other amplifiers. They operate by rapidly switching back and forth between the supply rails, using pulse-width modulation, pulse-density modulation, or related techniques to produce a pulse train output. A simple low-pass filter may be used to attenuate their high-frequency content to provide analog output current and voltage. Little energy is dissipated in the amplifying transistors because they are always either fully on or fully off, so efficiency can exceed 90%.
The Korg MS-20 is a patchable semi-modular monophonic analog synthesizer which Korg released in 1978 and which was in production until 1983. It was part of Korg's MS series of instruments, which also included the single oscillator MS-10, the keyboardless MS-50 module, the SQ-10 sequencer, and the VC-10 Vocoder. Additional devices included the MS-01 Foot Controller, MS-02 Interface, MS-03 Signal Processor, and MS-04 Modulation Pedal.
Flicker-free is a term given to video displays, primarily cathode ray tubes, operating at a high refresh rate to reduce or eliminate the perception of screen flicker. For televisions, this involves operating at a 100 Hz or 120 Hz hertz field rate to eliminate flicker, compared to standard televisions that operate at 50 Hz or 60 Hz (NTSC), most simply done by displaying each field twice, rather than once. For computer displays, this is usually a refresh rate of 70–90 Hz, sometimes 100 Hz or higher. This should not be confused with motion interpolation, though they may be combined – see implementation, below.
An electronic speed control (ESC) is an electronic circuit that controls and regulates the speed of an electric motor. It may also provide reversing of the motor and dynamic braking. Miniature electronic speed controls are used in electrically powered radio controlled models. Full-size electric vehicles also have systems to control the speed of their drive motors.
A servo drive is an electronic amplifier used to power electric servomechanisms.
Pulse-frequency modulation (PFM) is a modulation method for representing an analog signal using only two levels. It is analogous to pulse-width modulation (PWM), in which the magnitude of an analog signal is encoded in the duty cycle of a square wave. Unlike PWM, in which the width of square pulses is varied at a constant frequency, PFM fixes the width of square pulses while varying the frequency. In other words, the frequency of the pulse train is varied in accordance with the instantaneous amplitude of the modulating signal at sampling intervals. The amplitude and width of the pulses are kept constant.
Servos are small, cheap, mass-produced servomotors or other actuators used for radio control and small-scale robotics.
Stochastic Signal Density Modulation (SSDM) is a novel power modulation technique primarily used for LED power control. The information is encoded - or the power level is set - using pulses that have pseudo-random widths. The pulses are produced so that, on average, the produced signal will have the desired ratio between high and low states. The main benefit of using SSDM over, for example, Pulse-width modulation (PWM), which is usually the preferred method for controlling LED power, is reduced electromagnetic interference. Figure 1 illustrates a SSDM signal and demonstrates how the average signal density approaches desired value. The pseudo-random pulses in the signal are visible.
Random pulse-width modulation (RPWM) is a modulation technique introduced for mitigating electromagnetic interference (EMI) of power converters by spreading the energy of the noise signal over a wider bandwidth, so that there are no significant peaks of the noise. This is achieved by randomly varying the main parameters of the pulse-width modulation signal.
