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A Voltage controller thyristor based dimmer rack An electrical schematic for a typical SCR-based light dimmer. A voltage controller, also called an AC voltage controller or AC regulator is an electronic module based on either thyristors, triodes for alternating current, silicon-controlled rectifiers or insulated-gate bipolar transistors, which converts a fixed voltage, fixed frequency ...
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.
In the circuit on the figure, a non-linearized VCR design, the voltage-controlled resistor, the LSK489C JFET, is used as a programmable voltage divider. The VGS supply sets the level of the output resistance of the JFET. The drain-to-source resistance of the JFET (R DS) and the drain resistor (R 1) form the voltage-divider network. The output ...
frame dimming: adjusts the brightness of the entire backlight based on the content displayed, as if local dimming was supported but only with a single zone; local dimming: multiple vertical or horizontal zones are individually controlled; direct-lit (DLED) or full-array: LEDs form an array directly behind the screen at equally spaced intervals.
Backlight dimming [ edit ] LED backlight are often dynamically controlled using the video information [ 22 ] (dynamic backlight control or dynamic "local dimming" LED backlight, also marketed as HDR, high dynamic range television, invented by Philips researchers Douglas Stanton, Martinus Stroomer and Adrianus de Vaan [ 23 ] [ 24 ] [ 25 ] ).
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 ...
One classic use for a chopper circuit and where the term is still in use is in chopper amplifiers. These are DC amplifiers. Some types of signals that need amplifying can be so small that an incredibly high gain is required, but very high gain DC amplifiers are much harder to build with low offset and 1 / f {\displaystyle 1/f} noise, and ...
Typically a dimmer has a starting address that represents the lowest-numbered dimmer in that pack, and the addressing increases from there to the highest-numbered dimmer. As an example, for two packs of six dimmers each, the first pack would start at address 1 and the second pack at address 7. Each slot in the DMX512 packet corresponds to one ...