Automatic Night Lamp With Alaram Circuit Diagram Explanation

In our day-to-day life, we got used to several automatic electrical and electronics appliances such as automatic cooker, temperature based automatic speed adjustable fan, automatic iron box, automatic washing machines, automatic coolers, and so on. In general, during night time we got used to switch on night lamps or bed lamps and wake up with an alarm in the morning at a specific time. But, these conventional night lamps need manual control for switching on at night time and switch off at day time. Similarly, keeping an alarm is basic thing required for maintaining our day with the proper time schedule. Frequently, we forget these basic things like switching off bed lamps and to set an alarm which may cause power loss and improper time schedule. Thus, here in this article we discuss about an automatic night lamp with alarm circuit.Primarily, we must what is automatic night lamp.

Automatic night lamp project is a simple electronic circuit that is used for switching on the night lamp during night time and switching off the night lamp during daytime automatically.

Automatic Night Lamp with Morning Alarm Circuit Diagram Explanation

Objective

The objective of this article is to learn the designing and to understand the explanation of the automatic night lamp circuit with morning alarm. This can also be used for automatic alarm in the day time (we can set an alarm at a specific time based on requirement) also by adding an alarm circuit.

Hardware Components Required

The major electrical and electronics components required for designing an automatic night lamp with morning alarm circuit diagram are as follows.

• Power supply block
• LDR (Light Dependent Resistor)
• IC NE555
• IC UM66
• Transistors (BC548)
• Speaker
• LED (white)
• Resistors, capacitors, and diodes.

Schematic Design of Automatic Night Lamp with Morning Alarm Circuit Diagram

The automatic night lamp with morning alarm circuit schematic diagram is shown in the figure. The hardware components listed above are connected as shown in the circuit diagram.

Circuit Explanation

The main component in the circuit is LDR which is called as a light dependent resistor, it is also called as a photo resistor or photo cell. This is a special type of resistor whose resistance changes based on the light illumination incident on the surface of the LDR. In general, during daytime or if day light (even the artificial light) incident on the surface of the LDR, then the resistance of the LDR reduces or remains low. Similarly, the LDR resistance goes very high (a few Mega Ohms) during night time or dark or when no light is incident on the surface of the LDR. Thus, we can say that the LDR works on the principle of photoconductivity.

The automatic night lamp circuit is given power supply using a standard step down transformer, bridge rectifier circuit formed using diodes, and IC 7806 DC voltage regulator along with smoothing capacitor. If the supply from the mains supply fails, then battery provided as backup supply can be used for giving the supply to the circuit. The rechargeable battery connected as backup can be charged from the mains supply with constant current using D5 diode and R1 resistor. This diode D5 which shown in the circuit eliminates the battery discharging in the case of mains failure.

The LDR sensor connected in the circuit is used for sensing the darkness or light inside or outside the room using the light or darkness illuminated on the LDR. In this automatic night lamp project with morning alarm circuit, two LDRs are used among which LDR1 is used for controlling the night lamp and LDR2 is used for controlling the morning alarm. The 555 timer IC used in the circuit is connected in monostable mode.

If once the day light is incident on the LDR1, then the LDR resistance goes low and thus low pulse is applied to the IC555 timer. Thus, the output of IC555 timer remains low at pin3. Hence, the white LED or night lamp remains off during entire daytime. But, during night time or when a darkness incident on the LDR1 then its resistance goes high and thus short pulse is applied to the IC555 timer. Thus, the output of IC555 timer goes high at pin3. Hence, the white LED or night lamp switches on or glow during entire night time. The C2 low-value capacitor connected to the 555timer trigger pin is used for continuous operation by maintaining the monostable state and also to eliminate timer effect. We can also adjust the ON time of the night lamp by varying (increasing) the C2 capacitor value.

Similarly, the LDR2 connected in the circuit is used for controlling the operation of alarm circuit. The LDR2 resistance during night time is very high, thus the transistor T1 doesn’t conduct in the night time. If once the LDR2 detects day light or once it is illuminated, then the resistance goes low causing the conduction of transistor T1. The IC UM66 connected in the circuit is a melody-generator. If the transistor starts conduction, then the voltage is applied to the IC UM66 from transistor emitter. Thus, the melody-generator IC starts generating melody which is further amplified by the T2 transistor amplifier. Hence, the circuit can be used for automatic night lamp with morning alarm.

For more technical information regarding the automatic night lamp project and to design an innovative embedded system based electronics projects you can approach us by posting your queries in the comments section below or you can also visit our international website www.efxkits.com.