1. Light Tracking Servo System Using Cadmium Sulfide Light Dependent Resistors Brandon Agtarap and Branden Nakahara

2. Introduction Applications o Will be used to develop a light tracking system model that follow the movement of light Arduino Based Light Tracking System o Tracks for the maximum intensity of light o When there is a decrease in intensity of light, it automatically changes its direction towards the brightest source o Uses Cadmium Sulfide light dependent resistors Arduino Based Lux Meter o Luminosity sensor using an advanced digital light sensor Lux is the SI unit of illuminance and luminous emittance 1

3. Specs ADC: o Digital Light Sensor Approximates Human Eye Response – filters out the 50-60 Hz lighting ripple 100 kHz or 400 kHz 0.1 to 40,000 Lux range o 1 Lux = 1.46e -7 Watts/cm 2 ~ full moon on a clear night o Arduino: Resolution: o (5 V) / (2 10 ) = 5.0 mV 4 Analog inputs CdS LDRs: o Spectrum Peak Value: 540 nm (yellow-green light) o At ambient room light: 20 ms rise time and 30 ms fall time o Performance Parameter:  = log(R10/R100) DAC: o Arduino: Pins 9 & 10 provide 8-bit PWM output 2

4. Block Diagram 3

5. Circuit 4

6. Circuit-continued 5

7. Data 6 ColorWavelength (nm) Resistance (Ohm) Δ resistance (Ohm) Violet4251850.05.0 Green5351601.05.0 Orange6001832.05.0 Resistance (kilo Ohm) Δ resistance (kilo Ohm) R(10 Lux)65.81.0 R(100 Lux)12.11.0 Theoretical Value: 0.8Measured Value: 0.74 ± 0.06

8. 7 Resistance of LDRs to different wavelength at 30cm

9. Thank You 8