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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 pulse width is a measure of the elapsed time between the leading and trailing edges of a single pulse of energy. The measure is typically used with electrical signals and is widely used in the fields of radar and power supplies. There are two closely related measures.
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.
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 ...
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 ...
The dimmer switch used in conjunction with a dimmable CFL must be matched to its power consumption range; [58] many dimmers installed for use with incandescent bulbs do not function acceptably below 40 W, whereas CFL applications commonly draw power in the range 7–20 W. Dimmable CFLs have been marketed before suitable dimmers are available.