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New lighting systems have not used magnetic ballasts since the turn of the century, however some older installations still remain. Fluorescent lamps with magnetic ballasts flicker at a normally unnoticeable frequency of 100 or 120 Hz (twice of the utility frequency; the lamp is lit on both the positive and negative half-wave of a cycle).
The design of most analogue dimmers meant that the output of the dimmer was not directly proportional to the input. Instead, as the operator brought up a fader, the dimmer would dim slowly at first, then quickly in the middle, then slowly at the top. The shape of the curve resembled that of the third quarter of a sine wave.
So far, two lighting methods have been shown to improve nighttime sleep in AD patients: (1) exposure to bright white light (at least 2500 lx and as high as 8000 lx at the cornea) for at least one hour in the morning, for two weeks and (2) exposure to 30 lx of blue light from LEDs, peaking at 470 nm at the eye for two hours.
The history of electric light is well documented, [11] and with the developments in lighting technology the profession of lighting developed alongside it. The development of high-efficiency, low-cost fluorescent lamps led to a reliance on electric light and a uniform blanket approach to lighting, but the energy crisis of the 1970s required more design consideration and reinvigorated the use of ...
The "beat effect" problem created when shooting photos under standard fluorescent lighting. A stroboscopic effect can be noticed, where something spinning at just the right speed may appear stationary if illuminated solely by a single fluorescent lamp. This effect is eliminated by paired lamps operating on a lead-lag ballast.
This design uses a roof-mounted light collector, large-diameter optical fiber, and modified efficient fluorescent lighting fixtures that have transparent rods connected to the optical fiber cables. Essentially no electricity is needed for daytime natural interior lighting.
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The controlled lighting should scale its output so that at 10 V, the controlled light should be at 100% of its potential output, and at 0 V it should at 0% output (i.e., off). Dimming devices may be designed to respond in various patterns to the intermediate voltages, giving output curves that are linear for: voltage output, actual light output ...