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May 11, 2017, 11:10 PM
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LCD backlight completion


When last we visited the LED backlight replacement, it needed a more precise way to control brightness than varying the DIM pin voltage. The proper way to use the FB pin voltage requires 2 voltage regulators: 1 to provide 5V to DIM & 1 to provide variable voltage to FB. The decision was made to try dividing the 5V with a 1k pot.

This worked quite well. The current drawn by FB was low enough that the pot accessed the full range of brightness by outputting 1.4V to 4.6V. It was much finer control than the DIM pin. The brightness was also more independant of input voltage, though not completely. So the proper way of using the DF6113 is 5V on the DIM pin/ENA wire & dividing the 5V with a 1k pot for the FB pin/DIM wire.

1/16" balsa was hot glued in to get the LEDs to press against the glass. It needed slightly more than 1/16" of filler.


It's now much brighter than even a modern phone. What a bobby dazzler, like the lion kingdom bought one. There's no artifacting from the LEDs. It's finally bright enough to use minimum waveform intensity. Soldered to the power switch, since that cuts off the 14V. The 15V connector on the back is always on & is really 14.7V. The power switch has 14V. The manes voltage is always on. Tweeked the pot so the 3 LEDs in series got 8.7V.
Last edited by Jack Crossfire; May 11, 2017 at 11:15 PM.
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