This is a very simple low pass RC filter that is being added to an 1602 LCD display on the contrast pin in order to be able to programaticaly change the contrast from the code and not use a variable resistor.
The schematic is part of my instructional video on how the 1602 display can be controlled:
[![1602 LCD contrast control with Arduino //Arduino Tricks](http://img.youtube.com/vi/XA5Dvjg0J_c/0...
Repurposing an old laptop power supply (18vdc) and dozens (actually - hundreds...) of white LEDs from old solar powered Christmas lights, to build an illuminated 'Merry Christmas' sign (a la Big Clive's Arcade sign).
The LEDs are made into strings of 5, each with a current limiting resistor, and a switching transistor to control the string. The transistors are switched from the outputs of multip...
Uses 328PU to turn off light or turn on as needed, Using much software. But it has micro wave detection, pir detection, audio detection, and light detection.
A board to pull the last little bit of juice from a battery (down to around 500mV or so under load) and use this to power an external Li-ion charger (at 5V). Uses an Arduino Nano to control shutdown and to track the amount of power moved around via a coulomb counter.
Based on the Arduitape by Duncan Edwards. Download his firmware from http://arduitape.blogspot.com/ and remember to support him and his work.
Arduino Micro SD Card Reader Module
IIC/I2C 1602 44780 LCD Display
Arduino Audio Amplifier Board
2 x 3.5mm Audio Jacks
1 x 2.5mm Audio Jack
5 x Momentary Push Buttons
3 x 2 Pin Header
1 x 4 Pin Header
1 x 5 Pin Header
2 x 6...