Dimming the Raduino Display
by Don Cantrell, ND6T
The Raduino display can be a bit too bright for
some folks. The backlight only needs to be bright enough to make the display
readable, not to where you can read a book by it. In the sunlight it can be
easily read without the internal lighting so that energy is just being wasted.
I brought the brightness of my BITX LCD down by replacing the 110 ohm ballast
resistor for that LED with a 470 ohm
unit.
On the end of the display where you can see the
LED connection you should find a chip labeled R7. It will be on the end next to
the USB when the Arduino board is plugged in. That is the device in the photo
labeled “111” (that means a “1” followed by a “1” with “1” zero following it:
110 ohms). Replace it with a higher value to dim the light.
Now I can photograph it and read the indications. I saved 18 milliamps of current drain, too.
de ND6T
On one of my projects, I used PWM on the Arduino to dim the display. Put an NPN transistor in the ground side of the backlight, connect base of transistor to the PWM through a 4.7k resistor.
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