The LC-25B Lighting controller is designed for dimming the backlight of cockpit panels. Older cockpit panels (for example as used in the Airbus A320 series) use a large number of incandescent light bulbs and require a voltage of 1-5V with a high supply current.

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Many cockpit builders have tried to use PWM (pulse width modulation) dimming modules for this purpose. While this is the cheapest solution, it is often causing problems. PWM emits a large amount of EMI (high frequency electromagnetic interference) that often causes malfunctions of sensitive equipment like the FCU and MCDUs and disrupts the Arinc communication to this devices. Cheap PWM dimmers usually do not have any protections to prevent OEM panels from damage in case of a malfunction. They are also usually cheaply build and not designed to provide a high current over a longer time.

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The LC-25B controller is specifically designed to avoid this problems. It converts a 12V input voltage to a filtered regulated 1-5V DC voltage with low EMI. The LC-25B can directly be connected to the potentiometers used in original cockpit panels to control the brightness (for example the A320 111VU INTEG LT brightness control panel).

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To supply the backlight of a fully equipped A320 series cockpit at least 3 LC-25B are required. The exact current demand depends on the kind of OEM avionics installed. For example newer type MCDU, ACP and RMP panel modules use LED backlight and have a much lower backlight power consumption.

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A330/A340 and  other newer type cockpits use mostly LED backlight. For this type of cockpits, 1 LC-25B module is probably sufficient. It again depends on the type of avionic panels that are installed.

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