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Voltage Dimming: Dimming the Type S VIVISUN LED displays from daylight brightness at full rated voltage to night flying brightness is accomplished by simply reducing the applied voltage until the desired low level luminance is achieved.
Standard Dimming: All Type S colors have a uniform dimming range from 16 volts down to 10 volts as shown in Figure 18. The average display brightness for all colors is 20 ± 10 foot-lamberts at 14 VDC for the 28 VDC LED circuits as measured at 23°C.
Low Level Dimming: The Type S colors of blue, green, white and yellow used for caution and advisory signals can be dimmed to 1.0 foot-lamberts (red warning signals must remain at 15.0 foot-lamberts) as required by MIL-STD-411F for non-NVIS military aircrew stations. The average display luminance is 0.5 to 3.0 foot-lamberts at 7.2 VDC for the 28 VDC LED circuits as measured at 23°C. Figure 19 shows the dimming range.
NVIS Compatible Dimming: The Type S NVIS blue, NVIS green A and NVIS green B, NVIS white and NVIS yellow colors can be dimmed to 0.1 foot-lamberts as required by MIL-L-85762A and MIL-STD-411F for NVIS compatible military aircrew stations. The average display luminance is 0.05 to 0.3 foot-lamberts at 6.55 volts for the 28 VDC LED circuits as measured at 23°C. Figure 20 shows the dimming range.
Minimum Luminance Current: The 28 VDC LED displays require approximately 1 milliamp of current per quadrant before producing a perceptible level of luminance so the LEDs will not light inadvertently due to microamp currents.
Emergency Power Operation: The Type S displays are easily readable in emergency power conditions of 18 VDC producing in excess of 50 foot-lamberts at 18 VDC.
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