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This circuit is called a leading-edge dimmer or forward phase dimming. Waveform of the output voltage of a thyristor dimmer set for 60 volts RMS output, with 120 V input. The red trace shows the output device switching on about 5.5 ms after the input (blue) voltage crosses zero.
Leading edge modulation (top plot) uses a reverse sawtooth wave to generate the PWM. The PWM's leading edge is held at the leading edge of the window and the trailing edge is modulated. Trailing edge modulation (middle plot) uses a normal sawtooth wave to generate the PWM. The PWM's trailing edge is fixed and the leading edge is modulated.
A rising edge (or positive edge) is the low-to-high transition. [1] A falling edge (or negative edge) is the high-to-low transition. [1] In the case of a pulse, which consists of two edges: The leading edge (or front edge) is the first edge of the pulse. The trailing edge (or back edge) is the second edge of the pulse.
The angle between the upper and lower surfaces at the trailing edge is called the trailing edge angle. If the trailing edge angle is zero it is described as a cusped trailing edge. [5] In two-dimensional flow around a uniform wing of infinite span, the slope of the lift curve is determined primarily by the trailing edge angle. The slope is ...
In combined-function installations, the lights produce brighter red light as stop lights and dimmer red light as rear position lights. Regulations worldwide stipulate minimum intensity ratios between the bright (stop) and dim (position) modes, so that a vehicle displaying rear position lights will not be mistakenly interpreted as showing stop ...
Fluorescent lamps in various embodiments. Since their introduction as a commercial product in 1939, many different types of fluorescent lamp have been introduced. Systematic nomenclature identifies mass-market lamps as to overall shape, power rating, length, color, and other electrical and illuminating characteristics.
Two light switches in one box. The switch on the right is a dimmer switch. The switch box is covered by a decorative plate. The first light switch employing "quick-break technology" was invented by John Henry Holmes in 1884 in the Shieldfield district of Newcastle upon Tyne. [1]
Dimming fluorescent ballasts and dimming LED drivers often use 0–10 V control signals to control dimming functions. In many cases, the dimming range of the power supply or ballast is limited. If the light output can only be dimmed from 100% down to 10%, there must be a switch or relay available to kill power to the system and turn the light ...