Digital Potentiometer using Optical Encoder – 10KOhms

The primary application of the project is to replace the mechanical potentiometer with optical encoder which is long life, accurate, smooth in operation. The simple project has been designed around LS7184 quadrature clock converter IC from LSI semiconductor, AD5220-10 Digital potentiometer from Analog Devices, and optical encoder from Burns. Quadrature clocks derived from optical encoder, when applied to the A and B inputs of the LS7184, are converted to strings of Clock and an Up/down direction control. These outputs interfaced directly to AD5220-10 Digital Potentiometer IC. The AD5220-10 contains a single channel, 128 positions, and digitally-controlled 10K ohms variable resistor (VR) device. This device performs the same electronic adjustment function as a potentiometer. Jumper J1 provided for scale of the 3-state input to select resolution x1, x2 or x4. The input quadrature clock rate is multiplied by factors of 1, 2 and 4 in x1, x2 and x4 mode, respectively, in producing the output UP/DN clocks. x1, x2 and x4 modes selected by the MODE input logic.”