Automatic Night Lamp Circuit using Battery Power works on battery and saves energy, it turns ON in dark and OFF in light.
Furthermore, this circuit is good for bedroom, hallway, stairs and gives light at night and it also uses two 1.5V batteries and has 7555 timer chip, LDR as light sensor and LED as light.
Circuit Working:
Parts List:
| Components | Quantity |
|---|---|
| Resistors | |
| 1M 1/4 watt | 2 |
| 47k 1/4 watt | 1 |
| LDR | 1 |
| Capacitors | |
| Electrolytic 220µF 25V | 1 |
| Ceramic 100nF | 1 |
| Semiconductors | |
| CMOS Timer IC 7555 | 1 |
| LED 5mm 20mA | 1 |
| Schottky Diode 1N5819 | 1 |
| Battery 3V | 1 |
To begin with, this diagram shows how LED night lamp turns OFF in light and main part is LDR R4 which changes resistance with light.
At daytime LDR resistance is low and circuit stays OFF and at nighttime the LDR resistance is high and 7555 timer turns ON and LED lights up.
Then 7555 works like switch, resistors R1, R2 and LDR R4 make voltage divider and if voltage at pin 2 (trigger pin) goes below 1/3 of supply then pin 3 goes HIGH and LED is ON.
Now capacitor C1 100nF helps timer work well and capacitor C2 220µF filters the circuit to run smooth and finally, diode 1N5819 stops reverse current and circuit stays safe at 3V.
Formulas with Calculations:
Formulas and Calculations for Battery Night Lamp:
LDR Resistance:
LDR changes with light, in bright its 1k and in dark its 1M
Voltage at Pin 2 (Trigger):
Use voltage divider:
V_trigger = Vcc × R4 / (R1 + R4)
For LED to turn ON then V_trigger < 1V
Use formula:
T = 1.1 × R × C
R = 47k R3 and C = 220µF C2
T = 1.1 × 47000 × 0.00022 = 11.374 sec
How to Build:
To build a Automatic Night Lamp Circuit using Battery Power following the below mentioned steps:
- First, collect all parts from circuit diagram.
- Next, pin 1 of IC1 7555 goes GND.
- After that, pin 2 connect to pin 6 of IC1.
- Then pin 3 connect to + of C2 and negative of C2 connects between cathode of LED1 and D1 anode.
- Also, pin 4 connect to positive supply through R3.
- Now R2 connects between pin 6 and pin 7 and R1 goes between pin 7 and positive supply.
- LDR R4 connects from pin 4 to GND and C1 goes from pin 2 to GND.
- Finally, pin 8 connect to +3V battery and then connect battery positive to positive supply and negative to GND.
Conclusion:
To conclude, Automatic Night Lamp Circuit using Battery Power is an easy and low power project, it turns ON at dark and OFF at light and saves energy.
Also, IC 7555 helps it work smooth and uses less power an also we can change LDR or resistor to adjust light sensitivity.
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