This document describes a circuit to automatically open and close a glass window using light sensors. The circuit includes a power supply unit with a step-down transformer, rectifier, and voltage regulators to provide stable DC power from 230V AC. A PIC microcontroller measures light levels with an analog-to-digital converter connected to light dependent resistors. When light levels cross a threshold, the PIC activates a relay to control a DC motor that opens or closes the window. The circuit provides a simple automatic window control system based on ambient light levels.

1. AUTOMATIC OPENING AND CLOSING OF GLASS WINDOW USING LIGHT SENSORS Presented By Gopichand(06121A0421) A.Gouthami(06121A0421) M.Gouthami(06121A0422) S.Hari(06121A0424)

2. AIM:

3. Circuit Diagram:

5. We are utilizing for the same, the cheapest and commonly available energy source of 230v-50Hz and stepping down, rectifying, filtering and regulating the voltage.+5V Regulator LPF Positive Voltage Regulator IC 7812 PositiveCharge Capacitor Bridge Rectifier Step Down Transformer LPF Negative Voltage RegulatorIC 7912 Negative ChargeCapacitor LPF

9. The next alteration will temporarily cause the reverse.

11. A commonly used circuit for supplying large amounts of DC power is the bridge rectifier.

12. A bridge rectifier of four diodes (4*IN4007) are used to achieve full wave rectification.

14. A load resistor R1 is connected so that a reference to the ground is maintained. C1R1 is for bypassing ripples. C2R2 is used as a low pass filter, i.e. it passes only low frequency signals and bypasses high frequency signals. 1000f/25v : for the reduction of ripples from the pulsating. 10f/25v : for maintaining the stability of the voltage at the load side. O, 1f : for bypassing the high frequency disturbances.

15. VOLTAGE REGULATORS: The primary purpose of a regulator is to aid the rectifier and filter circuit in providing a constant DC voltage to the device. Power supplies without regulators have an inherent problem of changing DC voltage values due to variations in the load or due to fluctuations in the AC liner voltage. With a regulator connected to the DC output, the voltage can be maintained within a close tolerant region of the desired output. IC7812 and 7912 is used in this project for providing +12v and –12v DC supply.

17. Potential divider used for setting the dynamic response range of the reference supply i.e.., reference 5v can be used as it is or it can be made into a fraction of the 5v for example 1v so that readings in this range can be read with more precision. This is because the ADC has 10-bit resolution, which can be totally used for representing the 1v rather than 5v.

18. The pins 2-5,7-10,35 and 36 are used as the 10 channels of the ADC. To these pins the analog inputs to be processed by the ADC are given.

19. .

21. MICROCHIP SERIES – PIC 16F877 BASIC FEATURES: Operating speed: DC - 20 MHz clock input Up to 8K x 14 words of FLASH Program Memory Up to 368 x 8 bytes of Data Memory (RAM) Up to 256 x 8 bytes of EEPROM Data Memory Input / Output Ports – 33 Pins Interrupt capability (up to 14 sources) Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable operation In-Circuit Debugging via two pins

22. Relay Circuit: Relays are electro mechanical devices and basically consist of an electro magnet and a number of contact sets. The prime function of a relay is the switching of large currents from small currents. In fact currents of many hundreds or even thousands of Amps can be switched by just a couple of hundred milli Amps.

25. Light dependent resistors are a vital component in any electric circuit which is to be turned on and off automatically according to the level of ambient light - for example, solar powered garden lights, and night security lighting.

27. Applications:

28. Conclusion:

29. References:

31. Any Queries